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Is there a query (command) to truncate all the tables in a database in one operation? I want to know if I can do this with one single query.
Drop (i.e. remove tables)
mysql -Nse 'show tables' DATABASE_NAME | while read table; do mysql -e "drop table $table" DATABASE_NAME; done
Truncate (i.e. empty tables)
mysql -Nse 'show tables' DATABASE_NAME | while read table; do mysql -e "truncate table $table" DATABASE_NAME; done
The following query will generate a list of individual truncate commands for all database tables in a Mysql schema(s). (Replace dbSchemaName1 with name of your Db schema.)
SELECT CONCAT('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES WHERE table_schema IN ('dbSchemaName1','dbSchemaName2');
Copy the query results (which might look like the following) and paste the list of truncate commands into a SQL query tab in MySQL Worbench or your query command tool of choice:
TRUNCATE TABLE dbSchemaName1.table1;
TRUNCATE TABLE dbSchemaName1.table2;
TRUNCATE TABLE dbSchemaName1.table3;
Note: you may receive the following error:
ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails
This occurs if there are tables with foreign keys references to the table you are trying to drop/truncate.
To resolve this turn off foreign key checks before running the truncate commands:
SET FOREIGN_KEY_CHECKS=0; -- turn off foreign key checks
TRUNCATE TABLE dbSchemaName1.table1; -- truncate tables
TRUNCATE TABLE dbSchemaName1.table2;
TRUNCATE TABLE dbSchemaName1.table3;
SET FOREIGN_KEY_CHECKS=1; -- turn on foreign key checks
Use phpMyAdmin in this way:
Database View => Check All (tables) => Empty
If you want to ignore foreign key checks, you can uncheck the box that says:
[ ] Enable foreign key checks
You'll need to be running atleast version 4.5.0 or higher to get this checkbox.
Its not MySQL CLI-fu, but hey, it works!
MS SQL Server 2005+ (Remove PRINT for actual execution...)
EXEC sp_MSforeachtable 'PRINT ''TRUNCATE TABLE ?'''
If your database platform supports INFORMATION_SCHEMA views, take the results of the following query and execute them.
SELECT 'TRUNCATE TABLE ' + TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
Try this for MySQL:
SELECT Concat('TRUNCATE TABLE ', TABLE_NAME) FROM INFORMATION_SCHEMA.TABLES
Adding a semicolon to the Concat makes it easier to use e.g. from within mysql workbench.
SELECT Concat('TRUNCATE TABLE ', TABLE_NAME, ';') FROM INFORMATION_SCHEMA.TABLES
I found this to drop all tables in a database:
mysqldump -uUSERNAME -pPASSWORD --add-drop-table --no-data DATABASENAME | grep ^DROP | mysql -uUSERNAME -pPASSWORD DATABASENAME
Usefull if you are limited by hosting solution (not able to drop a whole database).
I modified it to truncate the tables. There is no "--add-truncate-table" for mysqldump, so i did:
mysqldump -uUSERNAME -pPASSWORD --add-drop-table --no-data DATABASENAME | grep ^DROP | sed -e 's/DROP TABLE IF EXISTS/TRUNCATE TABLE/g' | mysql -uUSERNAME -pPASSWORD DATABASENAME
works for me
--edit, fixing a typo in the last command
SET FOREIGN_KEY_CHECKS = 0;
SELECT #str := CONCAT('TRUNCATE TABLE ', table_schema, '.', table_name, ';')
FROM information_schema.tables
WHERE table_type = 'BASE TABLE'
AND table_schema IN ('db1_name','db2_name');
PREPARE stmt FROM #str;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET FOREIGN_KEY_CHECKS = 1;
I found it most simple to just do something like the code below, just replace the table names with your own. important make sure the last line is always
SET FOREIGN_KEY_CHECKS=1;
SET FOREIGN_KEY_CHECKS=0;
TRUNCATE `table1`;
TRUNCATE `table2`;
TRUNCATE `table3`;
TRUNCATE `table4`;
TRUNCATE `table5`;
TRUNCATE `table6`;
TRUNCATE `table7`;
SET FOREIGN_KEY_CHECKS=1;
This will print the command to truncate all tables:
SELECT GROUP_CONCAT(Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME) SEPARATOR ';') FROM INFORMATION_SCHEMA.TABLES where table_schema in ('my_db');
To truncate a table, one must drop the foreign key constraints mapped to the columns in this table from other tables (in fact on all tables in the specific DB/Schema).
So, all foreign key constraints must be dropped initially followed by table truncation.
Optionally, use the optimize table (in mysql, innodb engine esp) to reclaim the used data space/size to OS after data truncation.
Once data truncation is carried out, create the same foreign key constraints again on the same table.
See below a script that would generate the script to carry out the above operations.
SELECT CONCAT('ALTER TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,' DROP FOREIGN KEY ',CONSTRAINT_NAME,';') FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE='FOREIGN KEY' AND TABLE_SCHEMA='<TABLE SCHEMA>'
UNION
SELECT CONCAT('TRUNCATE TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,';') FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA='<TABLE SCHEMA>' AND TABLE_TYPE='BASE TABLE'
UNION
SELECT CONCAT('OPTIMIZE TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,';') FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA='<TABLE SCHEMA>' AND TABLE_TYPE='BASE TABLE'
UNION
SELECT CONCAT('ALTER TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,' ADD CONSTRAINT ',CONSTRAINT_NAME,' FOREIGN KEY(',COLUMN_NAME,')',' REFERENCES ',REFERENCED_TABLE_NAME,'(',REFERENCED_COLUMN_NAME,');') FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE CONSTRAINT_NAME LIKE 'FK%' AND TABLE_SCHEMA='<TABLE SCHEMA>'
INTO OUTFILE "C:/DB Truncate.sql" LINES TERMINATED BY '\n';
Now, run the Db Truncate.sql script generated
Benefits.
1) Reclaim disk space
2) Not needed to drop and recreate the DB/Schema with the same structure
Drawbacks.
1) FK constraints should be names in the table with the name containing 'FK' in the constraint name.
if using sql server 2005, there is a hidden stored procedure that allows you to execute a command or a set of commands against all tables inside a database. Here is how you would call TRUNCATE TABLE with this stored procedure:
EXEC [sp_MSforeachtable] #command1="TRUNCATE TABLE ?"
Here is a good article that elaborates further.
For MySql, however, you could use mysqldump and specify the --add-drop-tables and --no-data options to drop and create all tables ignoring the data. like this:
mysqldump -u[USERNAME] -p[PASSWORD] --add-drop-table --no-data [DATABASE]
mysqldump usage guide from dev.mysql
Here is my variant to have 'one statement to truncate 'em all'.
First, I am using a separate database named 'util' for my helper stored procedures. The code of my stored procedure to truncate all tables is:
DROP PROCEDURE IF EXISTS trunctables;
DELIMITER ;;
CREATE PROCEDURE trunctables(theDb varchar(64))
BEGIN
declare tname varchar(64);
declare tcursor CURSOR FOR
SELECT table_name FROM information_schema.tables WHERE table_type <> 'VIEW' AND table_schema = theDb;
SET FOREIGN_KEY_CHECKS = 0;
OPEN tcursor;
l1: LOOP
FETCH tcursor INTO tname;
if tname = NULL then leave l1; end if;
set #sql = CONCAT('truncate `', theDB, '`.`', tname, '`');
PREPARE stmt from #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END LOOP l1;
CLOSE tcursor;
SET FOREIGN_KEY_CHECKS = 1;
END ;;
DELIMITER ;
Once you have this stored procedure in your util database, you can call it like
call util.trunctables('nameofdatabase');
which is now exactly one statement :-)
Use this and form the query
SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES where table_schema in (db1,db2)
INTO OUTFILE '/path/to/file.sql';
Now use this to use this query
mysql -u username -p </path/to/file.sql
if you get an error like this
ERROR 1701 (42000) at line 3: Cannot truncate a table referenced in a foreign key constraint
the easiest way to go through is at the top of your file add this line
SET FOREIGN_KEY_CHECKS=0;
which says that we don't want to check the foreign key constraints while going through this file.
It will truncate all tables in databases db1 and bd2.
here for i know here
SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES where table_schema in ('databasename1','databasename2');
If cannot delete or update a parent row: a foreign key constraint fails
That happens if there are tables with foreign keys references to the table you are trying to drop/truncate.
Before truncating tables All you need to do is:
SET FOREIGN_KEY_CHECKS=0;
Truncate your tables and change it back to
SET FOREIGN_KEY_CHECKS=1;
user this php code
$truncate = mysql_query("SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';') as tables_query FROM INFORMATION_SCHEMA.TABLES where table_schema in ('databasename')");
while($truncateRow=mysql_fetch_assoc($truncate)){
mysql_query($truncateRow['tables_query']);
}
?>
check detail here
link
No. There is no single command to truncate all mysql tables at once. You will have to create a small script to truncate the tables one by one.
ref: http://dev.mysql.com/doc/refman/5.0/en/truncate-table.html
This worked for me. Change database, username and password accordingly.
mysql -Nse 'show tables' -D DATABASE -uUSER -pPWD | while read table; do echo "SET FOREIGN_KEY_CHECKS = 0;drop table \`$table\`;SET FOREIGN_KEY_CHECKS = 1;"; done | mysql DATABASE -uUSER -pPWD
Ans by battousaix is perfect!
I just used his answer and created the final working command for truncate database tables.
mysql -P 3306 -h YOUR_HOST_HERE -u YOUR_USERNAME_HERE -pYOUR_PASSWORD_HERE -Nse 'show tables' DATABASE_NAME | while read table; do mysql -P 3306 -h YOUR_HOST_HERE -u YOUR_USERNAME_HERE -pYOUR_PASSWORD_HERE -e "SET FOREIGN_KEY_CHECKS = 0; truncate table $table" DATABASE_NAME; done
The above command will work perfectly for the MySQL server.
Also, It's included.
SET FOREIGN_KEY_CHECKS = 0
Here is a procedure that should truncate all tables in the local database.
Let me know if it doesn't work and I'll delete this answer.
Untested
CREATE PROCEDURE truncate_all_tables()
BEGIN
-- Declare local variables
DECLARE done BOOLEAN DEFAULT 0;
DECLARE cmd VARCHAR(2000);
-- Declare the cursor
DECLARE cmds CURSOR
FOR
SELECT CONCAT('TRUNCATE TABLE ', TABLE_NAME) FROM INFORMATION_SCHEMA.TABLES;
-- Declare continue handler
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done=1;
-- Open the cursor
OPEN cmds;
-- Loop through all rows
REPEAT
-- Get order number
FETCH cmds INTO cmd;
-- Execute the command
PREPARE stmt FROM cmd;
EXECUTE stmt;
DROP PREPARE stmt;
-- End of loop
UNTIL done END REPEAT;
-- Close the cursor
CLOSE cmds;
END;
I find that TRUNCATE TABLE .. has trouble with foreign key constraints, even after a NOCHECK CONSTRAINT ALL, so I use a DELETE FROM statement instead. This does mean that identity seeds are not reset, you could always add a DBCC CHECKIDENT to achieve this.
I Use the code below to print out to the message window the sql for truncating all the tables in the database, before running it. It just makes it a bit harder to make a mistake.
EXEC sp_MSforeachtable 'PRINT ''ALTER TABLE ? NOCHECK CONSTRAINT ALL'''
EXEC sp_MSforeachtable 'print ''DELETE FROM ?'''
EXEC sp_MSforeachtable 'print ''ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all'''
I know this isn't exactly one command, but the desired result can be achieved from within phpMyAdmin by following these steps:
Select (all) tables to be removed (Check All)
Select "Drop" / "Truncate" from the "With selected:" list
On the confirmation page ("Do you really want to:") copy the query (everything with the red background)
Go at the top and click on SQL and write: "SET FOREIGN_KEY_CHECKS=0;" then paste the previously copied query
Click "Go"
The idea is to quickly get all the tables from the database (which you do in 5 seconds and 2 clicks) but disable foreign key checks first. No CLI and no dropping the database and adding it again.
PHP single command:
php -r '$d="PUT_YOUR_DB_NAME_HERE"; $q="show tables"; $dt="drop table"; exec("mysql -Nse \"$q\" $d", $o); foreach($o as $e) `mysql -e "$dt $e" $d`;'
Executed PHP script:
$d="PUT_YOUR_DB_NAME_HERE";
$q="show tables";
$dt="drop table";
exec("mysql -Nse \"$q\" $d", $o);
foreach($o as $e)
`mysql -e "$dt $e" $d`;
I find the top answer to be amazing. However it fails when you have an authenticated MySQL Database user.
Here is a solution built on top of the top answer I linked. This solution securely handles authentication without having to:
Type the password for each table
Worry about your password leaking somewhere
Side-effects on other MySQL cnf files (~/.my.cnf) For more details on what these files do, check out resources section at the bottom of this answer.
1. Create local .my.cnf file
vi .temp.my.cnf
[client]
user=<admin_user_goes_here>
password=<admin_password_goes_here>
2. Truncate or drop all tables
2.A Truncate All Tables (empty only)
mysql --defaults-extra-file=.temp.my.cnf -Nse 'show tables' <db_name_goes_here> | while read table; do mysql --defaults-extra-file=.temp.my.cnf -e "truncate table $table" <db_name_goes_here>; done
2.B Drop All Tables (remove entirely)
mysql --defaults-extra-file=.temp.my.cnf -Nse 'show tables' <db_name_goes_here> | while read table; do mysql --defaults-extra-file=.temp.my.cnf -e "drop table $table" <db_name_goes_here>; done
3. Cleanup
Delete your user-password file
rm -rf .temp.my.cnf
Resources:
https://rtcamp.com/tutorials/mysql/mycnf-preference/
https://dev.mysql.com/doc/refman/8.0/en/option-files.html
https://dev.mysql.com/doc/refman/8.0/en/option-file-options.html#option_general_defaults-extra-file
I am not sure but I think there is one command using which you can copy the schema of database into new database, once you have done this you can delete the old database and after this you can again copy the database schema to the old name.
TB=$( mysql -Bse "show tables from DATABASE" );
for i in ${TB};
do echo "Truncating table ${i}";
mysql -e "set foreign_key_checks=0; set unique_checks=0;truncate table DATABASE.${i}; set foreign_key_checks=1; set unique_checks=1";
sleep 1;
done
--
David,
Thank you for taking the time to format the code, but this is how it is supposed to be applied.
-Kurt
On a UNIX or Linux box:
Make sure you are in a bash shell. These commands are to be run, from the command line as follows.
Note:
I store my credentials in my ~/.my.cnf file, so I don't need to supply them on the command line.
Note:
cpm is the database name
I am only showing a small sample of the results, from each command.
Find your foreign key constraints:
klarsen#Chaos:~$ mysql -Bse "select concat(table_name, ' depends on ', referenced_table_name)
from information_schema.referential_constraints
where constraint_schema = 'cpm'
order by referenced_table_name"
approval_external_system depends on approval_request
address depends on customer
customer_identification depends on customer
external_id depends on customer
credential depends on customer
email_address depends on customer
approval_request depends on customer
customer_status depends on customer
customer_image depends on customer
List the tables and row counts:
klarsen#Chaos:~$ mysql -Bse "SELECT table_name, table_rows FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'cpm'" | cat -n
1 address 297
2 approval_external_system 0
3 approval_request 0
4 country 189
5 credential 468
6 customer 6776
7 customer_identification 5631
8 customer_image 2
9 customer_status 13639
Truncate your tables:
klarsen#Chaos:~$ TB=$( mysql -Bse "show tables from cpm" ); for i in ${TB}; do echo "Truncating table ${i}"; mysql -e "set foreign_key_checks=0; set unique_checks=0;truncate table cpm.${i}; set foreign_key_checks=1; set unique_checks=1"; sleep 1; done
Truncating table address
Truncating table approval_external_system
Truncating table approval_request
Truncating table country
Truncating table credential
Truncating table customer
Truncating table customer_identification
Truncating table customer_image
Truncating table customer_status
Verify that it worked:
klarsen#Chaos:~$ mysql -Bse "SELECT table_name, table_rows FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'cpm'" | cat -n
1 address 0
2 approval_external_system 0
3 approval_request 0
4 country 0
5 credential 0
6 customer 0
7 customer_identification 0
8 customer_image 0
9 customer_status 0
10 email_address 0
On a Windows box:
NOTE:
cpm is the database name
C:\>for /F "tokens=*" %a IN ('mysql -Bse "show tables" cpm') do mysql -e "set foreign_key_checks=0; set unique_checks=0; truncate table %a; foreign_key_checks=1; set unique_checks=1" cpm
The following MySQL query will itself produce a single query that will truncate all tables in a given database. It bypasses FOREIGN keys:
SELECT CONCAT(
'SET FOREIGN_KEY_CHECKS=0; ',
GROUP_CONCAT(dropTableSql SEPARATOR '; '), '; ',
'SET FOREIGN_KEY_CHECKS=1;'
) as dropAllTablesSql
FROM ( SELECT Concat('TRUNCATE TABLE ', table_schema, '.', TABLE_NAME) AS dropTableSql
FROM INFORMATION_SCHEMA.TABLES
WHERE table_schema = 'DATABASE_NAME' ) as queries
mysqldump -u root -p --no-data dbname > schema.sql
mysqldump -u root -p drop dbname
mysqldump -u root -p < schema.sql
Soln 1)
mysql> select group_concat('truncate',' ',table_name,';') from information_schema.tables where table_schema="db_name" into outfile '/tmp/a.txt';
mysql> /tmp/a.txt;
Soln 2)
- Export only structure of a db
- drop the database
- import the .sql of structure
-- edit ----
earlier in solution 1, i had mentioned concat() instead of group_concat() which would have not returned the desired result
We can write a bash script like below
truncate_tables_in_mysql() {
type mysql >/dev/null 2>&1 && echo "MySQL present." || sudo apt-get install -y mysql-client
tables=$(mysql -h 127.0.0.1 -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASSWORD -e "USE $BACKEND_DATABASE;
SHOW TABLES;")
tables_list=($tables)
query_string="USE $BACKEND_DATABASE; SET FOREIGN_KEY_CHECKS = 0;"
for table in "${tables_list[#]:1}"
do
query_string="$query_string TRUNCATE TABLE \`$table\`; "
done
query_string="$query_string SET FOREIGN_KEY_CHECKS = 1;"
mysql -h 127.0.0.1 -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASSWORD -e "$query_string"
}
You can replace env variables with your MySQL details. Using one command you can truncate all the tables in a DB.
Small addition to #Mathias Bynens's answer. When I run this I got an error because foreign key check
mysql -Nse 'SHOW TABLES' <database_name> | while read table; do mysql -e "SET FOREIGN_KEY_CHECKS=0; DROP TABLE $table" <database_name>; done
If there are views in the database it returns an error. I had to clear views manually by drop view <view_name>;
An idea could be to just drop and recreate the tables?
EDIT:
#Jonathan Leffler: True
Other Suggestion (or case you dont need to truncate ALL tables):
Why not just create a basic stored procedure to truncate specific tables
CREATE PROCEDURE [dbo].[proc_TruncateTables]
AS
TRUNCATE TABLE Table1
TRUNCATE TABLE Table2
TRUNCATE TABLE Table3
GO
<?php
// connect to database
$conn=mysqli_connect("localhost","user","password","database");
// check connection
if (mysqli_connect_errno()) {
exit('Connect failed: '. mysqli_connect_error());
}
// sql query
$sql =mysqli_query($conn,"TRUNCATE " . TABLE_NAME);
// Print message
if ($sql === TRUE) {
echo 'data delete successfully';
}
else {
echo 'Error: '. $conn->error;
}
$conn->close();
?>
Here is code snippet which I use to clear a table. Just change $conn info and TABLE_NAME.
Is there a query (command) to truncate all the tables in a database in one operation? I want to know if I can do this with one single query.
Drop (i.e. remove tables)
mysql -Nse 'show tables' DATABASE_NAME | while read table; do mysql -e "drop table $table" DATABASE_NAME; done
Truncate (i.e. empty tables)
mysql -Nse 'show tables' DATABASE_NAME | while read table; do mysql -e "truncate table $table" DATABASE_NAME; done
The following query will generate a list of individual truncate commands for all database tables in a Mysql schema(s). (Replace dbSchemaName1 with name of your Db schema.)
SELECT CONCAT('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES WHERE table_schema IN ('dbSchemaName1','dbSchemaName2');
Copy the query results (which might look like the following) and paste the list of truncate commands into a SQL query tab in MySQL Worbench or your query command tool of choice:
TRUNCATE TABLE dbSchemaName1.table1;
TRUNCATE TABLE dbSchemaName1.table2;
TRUNCATE TABLE dbSchemaName1.table3;
Note: you may receive the following error:
ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails
This occurs if there are tables with foreign keys references to the table you are trying to drop/truncate.
To resolve this turn off foreign key checks before running the truncate commands:
SET FOREIGN_KEY_CHECKS=0; -- turn off foreign key checks
TRUNCATE TABLE dbSchemaName1.table1; -- truncate tables
TRUNCATE TABLE dbSchemaName1.table2;
TRUNCATE TABLE dbSchemaName1.table3;
SET FOREIGN_KEY_CHECKS=1; -- turn on foreign key checks
Use phpMyAdmin in this way:
Database View => Check All (tables) => Empty
If you want to ignore foreign key checks, you can uncheck the box that says:
[ ] Enable foreign key checks
You'll need to be running atleast version 4.5.0 or higher to get this checkbox.
Its not MySQL CLI-fu, but hey, it works!
MS SQL Server 2005+ (Remove PRINT for actual execution...)
EXEC sp_MSforeachtable 'PRINT ''TRUNCATE TABLE ?'''
If your database platform supports INFORMATION_SCHEMA views, take the results of the following query and execute them.
SELECT 'TRUNCATE TABLE ' + TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
Try this for MySQL:
SELECT Concat('TRUNCATE TABLE ', TABLE_NAME) FROM INFORMATION_SCHEMA.TABLES
Adding a semicolon to the Concat makes it easier to use e.g. from within mysql workbench.
SELECT Concat('TRUNCATE TABLE ', TABLE_NAME, ';') FROM INFORMATION_SCHEMA.TABLES
I found this to drop all tables in a database:
mysqldump -uUSERNAME -pPASSWORD --add-drop-table --no-data DATABASENAME | grep ^DROP | mysql -uUSERNAME -pPASSWORD DATABASENAME
Usefull if you are limited by hosting solution (not able to drop a whole database).
I modified it to truncate the tables. There is no "--add-truncate-table" for mysqldump, so i did:
mysqldump -uUSERNAME -pPASSWORD --add-drop-table --no-data DATABASENAME | grep ^DROP | sed -e 's/DROP TABLE IF EXISTS/TRUNCATE TABLE/g' | mysql -uUSERNAME -pPASSWORD DATABASENAME
works for me
--edit, fixing a typo in the last command
SET FOREIGN_KEY_CHECKS = 0;
SELECT #str := CONCAT('TRUNCATE TABLE ', table_schema, '.', table_name, ';')
FROM information_schema.tables
WHERE table_type = 'BASE TABLE'
AND table_schema IN ('db1_name','db2_name');
PREPARE stmt FROM #str;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET FOREIGN_KEY_CHECKS = 1;
I found it most simple to just do something like the code below, just replace the table names with your own. important make sure the last line is always
SET FOREIGN_KEY_CHECKS=1;
SET FOREIGN_KEY_CHECKS=0;
TRUNCATE `table1`;
TRUNCATE `table2`;
TRUNCATE `table3`;
TRUNCATE `table4`;
TRUNCATE `table5`;
TRUNCATE `table6`;
TRUNCATE `table7`;
SET FOREIGN_KEY_CHECKS=1;
This will print the command to truncate all tables:
SELECT GROUP_CONCAT(Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME) SEPARATOR ';') FROM INFORMATION_SCHEMA.TABLES where table_schema in ('my_db');
To truncate a table, one must drop the foreign key constraints mapped to the columns in this table from other tables (in fact on all tables in the specific DB/Schema).
So, all foreign key constraints must be dropped initially followed by table truncation.
Optionally, use the optimize table (in mysql, innodb engine esp) to reclaim the used data space/size to OS after data truncation.
Once data truncation is carried out, create the same foreign key constraints again on the same table.
See below a script that would generate the script to carry out the above operations.
SELECT CONCAT('ALTER TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,' DROP FOREIGN KEY ',CONSTRAINT_NAME,';') FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE='FOREIGN KEY' AND TABLE_SCHEMA='<TABLE SCHEMA>'
UNION
SELECT CONCAT('TRUNCATE TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,';') FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA='<TABLE SCHEMA>' AND TABLE_TYPE='BASE TABLE'
UNION
SELECT CONCAT('OPTIMIZE TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,';') FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA='<TABLE SCHEMA>' AND TABLE_TYPE='BASE TABLE'
UNION
SELECT CONCAT('ALTER TABLE ',TABLE_SCHEMA,'.',TABLE_NAME,' ADD CONSTRAINT ',CONSTRAINT_NAME,' FOREIGN KEY(',COLUMN_NAME,')',' REFERENCES ',REFERENCED_TABLE_NAME,'(',REFERENCED_COLUMN_NAME,');') FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE CONSTRAINT_NAME LIKE 'FK%' AND TABLE_SCHEMA='<TABLE SCHEMA>'
INTO OUTFILE "C:/DB Truncate.sql" LINES TERMINATED BY '\n';
Now, run the Db Truncate.sql script generated
Benefits.
1) Reclaim disk space
2) Not needed to drop and recreate the DB/Schema with the same structure
Drawbacks.
1) FK constraints should be names in the table with the name containing 'FK' in the constraint name.
if using sql server 2005, there is a hidden stored procedure that allows you to execute a command or a set of commands against all tables inside a database. Here is how you would call TRUNCATE TABLE with this stored procedure:
EXEC [sp_MSforeachtable] #command1="TRUNCATE TABLE ?"
Here is a good article that elaborates further.
For MySql, however, you could use mysqldump and specify the --add-drop-tables and --no-data options to drop and create all tables ignoring the data. like this:
mysqldump -u[USERNAME] -p[PASSWORD] --add-drop-table --no-data [DATABASE]
mysqldump usage guide from dev.mysql
Here is my variant to have 'one statement to truncate 'em all'.
First, I am using a separate database named 'util' for my helper stored procedures. The code of my stored procedure to truncate all tables is:
DROP PROCEDURE IF EXISTS trunctables;
DELIMITER ;;
CREATE PROCEDURE trunctables(theDb varchar(64))
BEGIN
declare tname varchar(64);
declare tcursor CURSOR FOR
SELECT table_name FROM information_schema.tables WHERE table_type <> 'VIEW' AND table_schema = theDb;
SET FOREIGN_KEY_CHECKS = 0;
OPEN tcursor;
l1: LOOP
FETCH tcursor INTO tname;
if tname = NULL then leave l1; end if;
set #sql = CONCAT('truncate `', theDB, '`.`', tname, '`');
PREPARE stmt from #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END LOOP l1;
CLOSE tcursor;
SET FOREIGN_KEY_CHECKS = 1;
END ;;
DELIMITER ;
Once you have this stored procedure in your util database, you can call it like
call util.trunctables('nameofdatabase');
which is now exactly one statement :-)
Use this and form the query
SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES where table_schema in (db1,db2)
INTO OUTFILE '/path/to/file.sql';
Now use this to use this query
mysql -u username -p </path/to/file.sql
if you get an error like this
ERROR 1701 (42000) at line 3: Cannot truncate a table referenced in a foreign key constraint
the easiest way to go through is at the top of your file add this line
SET FOREIGN_KEY_CHECKS=0;
which says that we don't want to check the foreign key constraints while going through this file.
It will truncate all tables in databases db1 and bd2.
here for i know here
SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES where table_schema in ('databasename1','databasename2');
If cannot delete or update a parent row: a foreign key constraint fails
That happens if there are tables with foreign keys references to the table you are trying to drop/truncate.
Before truncating tables All you need to do is:
SET FOREIGN_KEY_CHECKS=0;
Truncate your tables and change it back to
SET FOREIGN_KEY_CHECKS=1;
user this php code
$truncate = mysql_query("SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';') as tables_query FROM INFORMATION_SCHEMA.TABLES where table_schema in ('databasename')");
while($truncateRow=mysql_fetch_assoc($truncate)){
mysql_query($truncateRow['tables_query']);
}
?>
check detail here
link
No. There is no single command to truncate all mysql tables at once. You will have to create a small script to truncate the tables one by one.
ref: http://dev.mysql.com/doc/refman/5.0/en/truncate-table.html
This worked for me. Change database, username and password accordingly.
mysql -Nse 'show tables' -D DATABASE -uUSER -pPWD | while read table; do echo "SET FOREIGN_KEY_CHECKS = 0;drop table \`$table\`;SET FOREIGN_KEY_CHECKS = 1;"; done | mysql DATABASE -uUSER -pPWD
Ans by battousaix is perfect!
I just used his answer and created the final working command for truncate database tables.
mysql -P 3306 -h YOUR_HOST_HERE -u YOUR_USERNAME_HERE -pYOUR_PASSWORD_HERE -Nse 'show tables' DATABASE_NAME | while read table; do mysql -P 3306 -h YOUR_HOST_HERE -u YOUR_USERNAME_HERE -pYOUR_PASSWORD_HERE -e "SET FOREIGN_KEY_CHECKS = 0; truncate table $table" DATABASE_NAME; done
The above command will work perfectly for the MySQL server.
Also, It's included.
SET FOREIGN_KEY_CHECKS = 0
Here is a procedure that should truncate all tables in the local database.
Let me know if it doesn't work and I'll delete this answer.
Untested
CREATE PROCEDURE truncate_all_tables()
BEGIN
-- Declare local variables
DECLARE done BOOLEAN DEFAULT 0;
DECLARE cmd VARCHAR(2000);
-- Declare the cursor
DECLARE cmds CURSOR
FOR
SELECT CONCAT('TRUNCATE TABLE ', TABLE_NAME) FROM INFORMATION_SCHEMA.TABLES;
-- Declare continue handler
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done=1;
-- Open the cursor
OPEN cmds;
-- Loop through all rows
REPEAT
-- Get order number
FETCH cmds INTO cmd;
-- Execute the command
PREPARE stmt FROM cmd;
EXECUTE stmt;
DROP PREPARE stmt;
-- End of loop
UNTIL done END REPEAT;
-- Close the cursor
CLOSE cmds;
END;
I find that TRUNCATE TABLE .. has trouble with foreign key constraints, even after a NOCHECK CONSTRAINT ALL, so I use a DELETE FROM statement instead. This does mean that identity seeds are not reset, you could always add a DBCC CHECKIDENT to achieve this.
I Use the code below to print out to the message window the sql for truncating all the tables in the database, before running it. It just makes it a bit harder to make a mistake.
EXEC sp_MSforeachtable 'PRINT ''ALTER TABLE ? NOCHECK CONSTRAINT ALL'''
EXEC sp_MSforeachtable 'print ''DELETE FROM ?'''
EXEC sp_MSforeachtable 'print ''ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all'''
I know this isn't exactly one command, but the desired result can be achieved from within phpMyAdmin by following these steps:
Select (all) tables to be removed (Check All)
Select "Drop" / "Truncate" from the "With selected:" list
On the confirmation page ("Do you really want to:") copy the query (everything with the red background)
Go at the top and click on SQL and write: "SET FOREIGN_KEY_CHECKS=0;" then paste the previously copied query
Click "Go"
The idea is to quickly get all the tables from the database (which you do in 5 seconds and 2 clicks) but disable foreign key checks first. No CLI and no dropping the database and adding it again.
PHP single command:
php -r '$d="PUT_YOUR_DB_NAME_HERE"; $q="show tables"; $dt="drop table"; exec("mysql -Nse \"$q\" $d", $o); foreach($o as $e) `mysql -e "$dt $e" $d`;'
Executed PHP script:
$d="PUT_YOUR_DB_NAME_HERE";
$q="show tables";
$dt="drop table";
exec("mysql -Nse \"$q\" $d", $o);
foreach($o as $e)
`mysql -e "$dt $e" $d`;
I find the top answer to be amazing. However it fails when you have an authenticated MySQL Database user.
Here is a solution built on top of the top answer I linked. This solution securely handles authentication without having to:
Type the password for each table
Worry about your password leaking somewhere
Side-effects on other MySQL cnf files (~/.my.cnf) For more details on what these files do, check out resources section at the bottom of this answer.
1. Create local .my.cnf file
vi .temp.my.cnf
[client]
user=<admin_user_goes_here>
password=<admin_password_goes_here>
2. Truncate or drop all tables
2.A Truncate All Tables (empty only)
mysql --defaults-extra-file=.temp.my.cnf -Nse 'show tables' <db_name_goes_here> | while read table; do mysql --defaults-extra-file=.temp.my.cnf -e "truncate table $table" <db_name_goes_here>; done
2.B Drop All Tables (remove entirely)
mysql --defaults-extra-file=.temp.my.cnf -Nse 'show tables' <db_name_goes_here> | while read table; do mysql --defaults-extra-file=.temp.my.cnf -e "drop table $table" <db_name_goes_here>; done
3. Cleanup
Delete your user-password file
rm -rf .temp.my.cnf
Resources:
https://rtcamp.com/tutorials/mysql/mycnf-preference/
https://dev.mysql.com/doc/refman/8.0/en/option-files.html
https://dev.mysql.com/doc/refman/8.0/en/option-file-options.html#option_general_defaults-extra-file
I am not sure but I think there is one command using which you can copy the schema of database into new database, once you have done this you can delete the old database and after this you can again copy the database schema to the old name.
TB=$( mysql -Bse "show tables from DATABASE" );
for i in ${TB};
do echo "Truncating table ${i}";
mysql -e "set foreign_key_checks=0; set unique_checks=0;truncate table DATABASE.${i}; set foreign_key_checks=1; set unique_checks=1";
sleep 1;
done
--
David,
Thank you for taking the time to format the code, but this is how it is supposed to be applied.
-Kurt
On a UNIX or Linux box:
Make sure you are in a bash shell. These commands are to be run, from the command line as follows.
Note:
I store my credentials in my ~/.my.cnf file, so I don't need to supply them on the command line.
Note:
cpm is the database name
I am only showing a small sample of the results, from each command.
Find your foreign key constraints:
klarsen#Chaos:~$ mysql -Bse "select concat(table_name, ' depends on ', referenced_table_name)
from information_schema.referential_constraints
where constraint_schema = 'cpm'
order by referenced_table_name"
approval_external_system depends on approval_request
address depends on customer
customer_identification depends on customer
external_id depends on customer
credential depends on customer
email_address depends on customer
approval_request depends on customer
customer_status depends on customer
customer_image depends on customer
List the tables and row counts:
klarsen#Chaos:~$ mysql -Bse "SELECT table_name, table_rows FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'cpm'" | cat -n
1 address 297
2 approval_external_system 0
3 approval_request 0
4 country 189
5 credential 468
6 customer 6776
7 customer_identification 5631
8 customer_image 2
9 customer_status 13639
Truncate your tables:
klarsen#Chaos:~$ TB=$( mysql -Bse "show tables from cpm" ); for i in ${TB}; do echo "Truncating table ${i}"; mysql -e "set foreign_key_checks=0; set unique_checks=0;truncate table cpm.${i}; set foreign_key_checks=1; set unique_checks=1"; sleep 1; done
Truncating table address
Truncating table approval_external_system
Truncating table approval_request
Truncating table country
Truncating table credential
Truncating table customer
Truncating table customer_identification
Truncating table customer_image
Truncating table customer_status
Verify that it worked:
klarsen#Chaos:~$ mysql -Bse "SELECT table_name, table_rows FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'cpm'" | cat -n
1 address 0
2 approval_external_system 0
3 approval_request 0
4 country 0
5 credential 0
6 customer 0
7 customer_identification 0
8 customer_image 0
9 customer_status 0
10 email_address 0
On a Windows box:
NOTE:
cpm is the database name
C:\>for /F "tokens=*" %a IN ('mysql -Bse "show tables" cpm') do mysql -e "set foreign_key_checks=0; set unique_checks=0; truncate table %a; foreign_key_checks=1; set unique_checks=1" cpm
The following MySQL query will itself produce a single query that will truncate all tables in a given database. It bypasses FOREIGN keys:
SELECT CONCAT(
'SET FOREIGN_KEY_CHECKS=0; ',
GROUP_CONCAT(dropTableSql SEPARATOR '; '), '; ',
'SET FOREIGN_KEY_CHECKS=1;'
) as dropAllTablesSql
FROM ( SELECT Concat('TRUNCATE TABLE ', table_schema, '.', TABLE_NAME) AS dropTableSql
FROM INFORMATION_SCHEMA.TABLES
WHERE table_schema = 'DATABASE_NAME' ) as queries
mysqldump -u root -p --no-data dbname > schema.sql
mysqldump -u root -p drop dbname
mysqldump -u root -p < schema.sql
Soln 1)
mysql> select group_concat('truncate',' ',table_name,';') from information_schema.tables where table_schema="db_name" into outfile '/tmp/a.txt';
mysql> /tmp/a.txt;
Soln 2)
- Export only structure of a db
- drop the database
- import the .sql of structure
-- edit ----
earlier in solution 1, i had mentioned concat() instead of group_concat() which would have not returned the desired result
We can write a bash script like below
truncate_tables_in_mysql() {
type mysql >/dev/null 2>&1 && echo "MySQL present." || sudo apt-get install -y mysql-client
tables=$(mysql -h 127.0.0.1 -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASSWORD -e "USE $BACKEND_DATABASE;
SHOW TABLES;")
tables_list=($tables)
query_string="USE $BACKEND_DATABASE; SET FOREIGN_KEY_CHECKS = 0;"
for table in "${tables_list[#]:1}"
do
query_string="$query_string TRUNCATE TABLE \`$table\`; "
done
query_string="$query_string SET FOREIGN_KEY_CHECKS = 1;"
mysql -h 127.0.0.1 -P $MYSQL_PORT -u $MYSQL_USER -p$MYSQL_PASSWORD -e "$query_string"
}
You can replace env variables with your MySQL details. Using one command you can truncate all the tables in a DB.
Small addition to #Mathias Bynens's answer. When I run this I got an error because foreign key check
mysql -Nse 'SHOW TABLES' <database_name> | while read table; do mysql -e "SET FOREIGN_KEY_CHECKS=0; DROP TABLE $table" <database_name>; done
If there are views in the database it returns an error. I had to clear views manually by drop view <view_name>;
An idea could be to just drop and recreate the tables?
EDIT:
#Jonathan Leffler: True
Other Suggestion (or case you dont need to truncate ALL tables):
Why not just create a basic stored procedure to truncate specific tables
CREATE PROCEDURE [dbo].[proc_TruncateTables]
AS
TRUNCATE TABLE Table1
TRUNCATE TABLE Table2
TRUNCATE TABLE Table3
GO
<?php
// connect to database
$conn=mysqli_connect("localhost","user","password","database");
// check connection
if (mysqli_connect_errno()) {
exit('Connect failed: '. mysqli_connect_error());
}
// sql query
$sql =mysqli_query($conn,"TRUNCATE " . TABLE_NAME);
// Print message
if ($sql === TRUE) {
echo 'data delete successfully';
}
else {
echo 'Error: '. $conn->error;
}
$conn->close();
?>
Here is code snippet which I use to clear a table. Just change $conn info and TABLE_NAME.
I want to drop all databases with zero tables I was able to get the databases with tables using
SELECT table_schema, count(table_name) FROM information_schema.tables group by table_schema
But how can I delete the dbs not in this list. I can't do it manually because there are more then 500 dbs there.
About to know schemas without tables, you can try this:
SELECT * FROM information_schema.schemata S
WHERE NOT EXISTS
(SELECT 'TABLE' from information_schema.tables T
WHERE T.table_schema = S.schema_name)
Because in system table SCHEMATA you'll find all schemas of your server and in table TABLES you'll find all tables in all schemas
The upper query must be input on cursor, so you must use a prepared statement to execute your cursor, because your DROP DATABASE has a variable (your schema_table) and it can be ran only with a prepared statement
Used the method posted by #dnoeth in the comments with a slightly diffrent query to get the drop commands and then with some Notepad++ magic executed them to drop all empty databases
SELECT concat('drop database ',schema_name) FROM information_schema.schemata
WHERE schema_name NOT IN
(SELECT TABLE_SCHEMA FROM information_schema.tables)
I've found another thread on this question, but I wasn't able to use its solutions, so I thought I'd ask with more clarity and detail.
I have a large MySQL database representing a vBulletin forum. For several years, this forum has had an error generated on each view, each time creating a new table named aagregate_temp_1251634200, aagregate_temp_1251734400, etc etc. There are about 20,000 of these tables in the database, and I wish to delete them all.
I want to issue a command that says the equivalent of DROP TABLE WHERE TABLE_NAME LIKE 'aggregate_temp%';.
Unfortunately this command doesn't work, and the Google results for this problem are full of elaborate stored procedures beyond my understanding and all seemingly tailored to the more complex problems of different posters.
Is it possible to write a simple statement that drops multiple tables based on a name like match?
There's no single statement to do that.
The simplest approach is to generate a set of statements, and execute them individually.
We can write a simple query that will generate the statements for us:
SELECT CONCAT('DROP TABLE `',t.table_schema,'`.`',t.table_name,'`;') AS stmt
FROM information_schema.tables t
WHERE t.table_schema = 'mydatabase'
AND t.table_name LIKE 'aggregate\_temp%' ESCAPE '\\'
ORDER BY t.table_name
The SELECT statement returns a rowset, but each row conveniently contains the exact SQL statement we need to execute to drop a table. (Note that information_schema is a builtin database that contains metadata. We'd need to replace mydatabase with the name of the database we want to drop tables from.
We can save the resultset from this query as a plain text file, remove any heading line, and voila, we've got a script we can execute in our SQL client.
There's no need for an elaborate stored procedure.
A little googling found this:
SELECT 'DROP TABLE "' + TABLE_NAME + '"'
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME LIKE 'prefix%'
This should generate a script.
Source: Drop all tables whose names begin with a certain string
From memory you have to use prepared statements, for example: plenty of samples on stack exchange
I would recommend this example:
SQL: deleting tables with prefix
The SQL from above, this one includes the specific databasename - it builds it for you
SELECT CONCAT( 'DROP TABLE ', GROUP_CONCAT(table_name) , ';' )
AS statement FROM information_schema.tables
WHERE table_schema = 'database_name' AND table_name LIKE 'myprefix_%';
Here is a different way to do it:
MySQL bulk drop table where table like?
This will delete all tables with prefix "mg_"
No need to copy and paste rowsets and in phpadmin copying and pasting is problematic as it will cut off long table names and replace them with '...' ruining set of sql commands.
Also note that '_' is a special character so thats why 'mg_' should be encoded as 'mg\_'
(and FOREIGN_KEY_CHECKS needs to be disabled in order to avoid error messages)
SET FOREIGN_KEY_CHECKS = 0;
SET GROUP_CONCAT_MAX_LEN=32768;
SET #tables = NULL;
SELECT GROUP_CONCAT('`', table_name, '`') INTO #tables
FROM information_schema.tables
WHERE table_schema = (SELECT DATABASE()) and table_name like 'mg\_%';
SELECT IFNULL(#tables,'dummy') INTO #tables;
SET #tables = CONCAT('DROP TABLE IF EXISTS ', #tables);
PREPARE stmt FROM #tables;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET FOREIGN_KEY_CHECKS = 1;
I'm trying to convert a whole database from MyISAM to InnoDB with this statement:
use information_schema;
SELECT CONCAT('ALTER TABLE ',table_schema,'.',table_name,' ENGINE=InnoDB;')
FROM information_schema.tables
WHERE engine = "MyISAM" AND table_type = "BASE TABLE" AND table_schema = "database";
and while I get a result that every table is changed for example:
ALTER TABLE database.action ENGINE=InnoDB;
when I check the table engines they're still MyISAM. The weird thing is that if I run the command separately
ALTER TABLE action ENGINE='InnoDB';
it works fine for that table.
Any tips on how to do the conversion for the whole database?
The SELECT statement you are running only generates strings; the strings it generates are not being executed as SQL statements. You'd need to take the resultset from that query, and then actually execute those statements as a separate step.