Use auto incremented ID in another column - mysql

I have two columns in my DB table, where the first one is auto incremented ID. In the second one I would like to have that ID mirrored. (I know it sound like design error, but I really need it)
Is it possible to configure it that way?


If you're using MySql 5.7.6 or later you can define the second id as a virtual column like this:
CREATE TABLE my_table (
id INT UNSIGNED AUTO_INCREMENT,
id_mirrored INT UNSIGNED AS (id)
);
This way the id_mirrored column isn't really stored in your database but instead it's evaluated when the row is read.
If you're using an earlier version of MySql creating a view is probably your best option. Views are basically virtual tables.
CREATE VIEW my_view AS
SELECT
t.id AS id,
t.id AS id_mirrored
FROM my_table t
Third option is to define the id_mirrored as a real column and add a trigger to give it it's value. The way to do this has already been described in other answers.


use TRIGGER
DELIMITER |: # switch delimiter to prevent execution of ;
CREATE TRIGGER `copy_id2c_name` BEFORE INSERT ON tb_name
FOR EACH ROW BEGIN
SELECT AUTO_INCREMENT INTO #AI FROM information_schema.tables WHERE table_schema = 'db_name' and table_name = 'tb_name';
set NEW.c_name = #AI;
END;
|: # execute code
DELIMITER ; // switch back original delimiter


You could use smth like LAST_INSERT_ID() in case you are using stored procedure.

Related

MySql Query to Update Auto increment Primary Key [duplicate]

How can I reset the AUTO_INCREMENT of a field?
I want it to start counting from 1 again.

You can reset the counter with:
ALTER TABLE tablename AUTO_INCREMENT = 1
For InnoDB you cannot set the auto_increment value lower or equal to the highest current index. (quote from ViralPatel):
Note that you cannot reset the counter to a value less than or equal
to any that have already been used. For MyISAM, if the value is less
than or equal to the maximum value currently in the AUTO_INCREMENT
column, the value is reset to the current maximum plus one. For
InnoDB, if the value is less than the current maximum value in the
column, no error occurs and the current sequence value is not changed.
See How can I reset an MySQL AutoIncrement using a MAX value from another table? on how to dynamically get an acceptable value.

SET #num := 0;
UPDATE your_table SET id = #num := (#num+1);
ALTER TABLE your_table AUTO_INCREMENT =1;

Simply like this:
ALTER TABLE tablename AUTO_INCREMENT = value;
Reference: 13.1.9 ALTER TABLE Statement

There is a very easy way with phpMyAdmin under the "operations" tab. In the table options you can set autoincrement to the number you want.

The best solution that worked for me:
ALTER TABLE my_table MODIFY COLUMN ID INT(10) UNSIGNED;
COMMIT;
ALTER TABLE my_table MODIFY COLUMN ID INT(10) UNSIGNED AUTO_INCREMENT;
COMMIT;
It's fast, works with InnoDB, and I don't need to know the current maximum value!
This way. the auto increment counter will reset and it will start automatically from the maximum value exists.

The highest rated answers to this question all recommend "ALTER yourtable AUTO_INCREMENT= value". However, this only works when value in the alter is greater than the current max value of the autoincrement column. According to the MySQL 8 documentation:
You cannot reset the counter to a value less than or equal to the value that is currently in use. For both InnoDB and MyISAM, if the value is less than or equal to the maximum value currently in the AUTO_INCREMENT column, the value is reset to the current maximum AUTO_INCREMENT column value plus one.
In essence, you can only alter AUTO_INCREMENT to increase the value of the autoincrement column, not reset it to 1, as the OP asks in the second part of the question. For options that actually allow you set the AUTO_INCREMENT downward from its current max, take a look at Reorder / reset auto increment primary key.

As of MySQL 5.6 you can use the simple ALTER TABLE with InnoDB:
ALTER TABLE tablename AUTO_INCREMENT = 1;
The documentation are updated to reflect this:
13.1.7 ALTER TABLE Statement
My testing also shows that the table is not copied. The value is simply changed.

Beware! TRUNCATE TABLE your_table will delete everything in your your_table.
You can also use the syntax TRUNCATE table like this:
TRUNCATE TABLE table_name

ALTER TABLE news_feed DROP id
ALTER TABLE news_feed ADD id BIGINT( 200 ) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (id)
I used this in some of my scripts. The id field is dropped and then added back with previous settings. All the existent fields within the database table are filled in with the new auto increment values. This should also work with InnoDB.
Note that all the fields within the table will be recounted and will have other ids!!!.

It is for an empty table:
ALTER TABLE `table_name` AUTO_INCREMENT = 1;
If you have data, but you want to tidy up it, I recommend to use this:
ALTER TABLE `table_name` DROP `auto_colmn`;
ALTER TABLE `table_name` ADD `auto_colmn` INT( {many you want} ) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (`auto_colmn`);

To update to the latest plus one id:
ALTER TABLE table_name AUTO_INCREMENT =
(SELECT (id+1) id FROM table_name order by id desc limit 1);
Edit:
SET #latestId = SELECT MAX(id) FROM table_name;
SET #nextId = #latestId + 1;
ALTER TABLE table_name AUTO_INCREMENT = #nextId;
Not tested please test before you run*

Warning: If your column has constraints or is connected as a foreign key to other tables this will have bad effects.
First, drop the column:
ALTER TABLE tbl_name DROP COLUMN column_id
Next, recreate the column and set it as FIRST (if you want it as the first column I assume):
ALTER TABLE tbl_access ADD COLUMN `access_id` int(10) NOT NULL PRIMARY KEY AUTO_INCREMENT FIRST

As of MySQL 5.6 the approach below works faster due to online DDL (note algorithm=inplace):
alter table tablename auto_increment=1, algorithm=inplace;

SET #num := 0;
UPDATE your_table SET id = #num := (#num+1);
ALTER TABLE your_table AUTO_INCREMENT =1;

ALTER TABLE tablename AUTO_INCREMENT = 1

Try to run this query:
ALTER TABLE tablename AUTO_INCREMENT = value;
Or try this query for the reset auto increment
ALTER TABLE `tablename` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL;
And set auto increment and then run this query:
ALTER TABLE `tablename` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT;

The auto-increment counter for a table can be (re)set in two ways:
By executing a query, like others already explained:
ALTER TABLE <table_name> AUTO_INCREMENT=<table_id>;
Using Workbench or another visual database design tool. I am going to show in Workbench how it is done - but it shouldn't be much different in other tools as well. By right clicking over the desired table and choosing Alter table from the context menu. On the bottom you can see all the available options for altering a table. Choose Options and you will get this form:
Then just set the desired value in the field Auto increment as shown in the image. This will basically execute the query shown in the first option.

If you're using PHPStorm's database tool you have to enter this in the database console:
ALTER TABLE <table_name> AUTO_INCREMENT = 0;

I tried to alter the table and set auto_increment to 1 but it did not work. I resolved to delete the column name I was incrementing, then create a new column with your preferred name and set that new column to increment from the onset.

I googled and found this question, but the answer I am really looking for fulfils two criteria:
using purely MySQL queries
reset an existing table auto-increment to max(id) + 1
Since I couldn't find exactly what I want here, I have cobbled the answer from various answers and sharing it here.
Few things to note:
the table in question is InnoDB
the table uses the field id with type as int as primary key
the only way to do this purely in MySQL is to use stored procedure
my images below are using SequelPro as the GUI. You should be able to adapt it based on your preferred MySQL editor
I have tested this on MySQL Ver 14.14 Distrib 5.5.61, for debian-linux-gnu
Step 1: Create Stored Procedure
create a stored procedure like this:
DELIMITER //
CREATE PROCEDURE reset_autoincrement(IN tablename varchar(200))
BEGIN
SET #get_next_inc = CONCAT('SELECT #next_inc := max(id) + 1 FROM ',tablename,';');
PREPARE stmt FROM #get_next_inc;
EXECUTE stmt;
SELECT #next_inc AS result;
DEALLOCATE PREPARE stmt;
set #alter_statement = concat('ALTER TABLE ', tablename, ' AUTO_INCREMENT = ', #next_inc, ';');
PREPARE stmt FROM #alter_statement;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END //
DELIMITER ;
Then run it.
Before run, it looks like this when you look under Stored Procedures in your database.
When I run, I simply select the stored procedure and press Run Selection
Note: the delimiters part are crucial. Hence if you copy and paste from the top selected answers in this question, they tend not to work for this reason.
After I run, I should see the stored procedure
If you need to change the stored procedure, you need to delete the stored procedure, then select to run again.
Step 2: Call the stored procedure
This time you can simply use normal MySQL queries.
call reset_autoincrement('products');
Originally from my own SQL queries notes in https://simkimsia.com/reset-mysql-autoincrement-to-max-id-plus-1/ and adapted for Stack Overflow.

delete from url_rewrite where 1=1;
ALTER TABLE url_rewrite AUTO_INCREMENT = 1;
and then reindex

ALTER TABLE `table_name` DROP `id`;
ALTER TABLE `table_name` ADD `id` INT NOT NULL AUTO_INCREMENT FIRST, ADD PRIMARY KEY (`id`) ;
Shortly,First we deleted id column then added it with primary key id again...

The best way is remove the field with AI and add it again with AI. It works for all tables.

You need to follow the advice from Miles M's comment and here is some PHP code that fixes the range in MySQL. Also you need to open up the my.ini file (MySQL) and change max_execution_time=60 to max_execution_time=6000; for large databases.
Don’t use "ALTER TABLE tablename AUTO_INCREMENT = 1". It will delete everything in your database.
$con = mysqli_connect($dbhost, $dbuser, $dbpass, $database);
$res = mysqli_query($con, "select * FROM data WHERE id LIKE id ORDER BY id ASC");
$count = 0;
while ($row = mysqli_fetch_array($res)){
$count++;
mysqli_query($con, "UPDATE data SET id='".$count."' WHERE id='".$row['id']."'");
}
echo 'Done reseting id';
mysqli_close($con);

I suggest you to go to Query Browser and do the following:
Go to schemata and find the table you want to alter.
Right click and select copy create statement.
Open a result tab and paste the create statement their.
Go to the last line of the create statement and look for the Auto_Increment=N,
(Where N is a current number for auto_increment field.)
Replace N with 1.
Press Ctrl + Enter.
Auto_increment should reset to one once you enter a new row in the table.
I don't know what will happen if you try to add a row where an auto_increment field value already exist.

MySQL Trigger INSERT copy's rows

I am trying to create a trigger (this is my first trigger, and question, so be gentle) that will insert new rows into two different tables.
* Edit *
Adding this in as I forgot to mention it until ypercube answered.
I am trying to avoid listing all of the column names, as in the real world usage the table this will be used on has a very large number of columns (not my design, too late to refactor).
* End Edit *
Here's what I have so far.
CREATE TABLE test_table (
id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
message VARCHAR(255)
);
CREATE TABLE test_table_copy LIKE test_table;
DELIMITER $$
CREATE TRIGGER copy_test_table_data AFTER INSERT ON test_table
FOR EACH ROW
BEGIN
INSERT INTO test_table_copy SELECT * FROM NEW;
END;$$
DELIMITER ;
Unfortunately this results in an error.
mysql> INSERT INTO test_table VALUES (1, 'This is a message');
ERROR 1146 (4502): Table 'test_db.NEW' doesn't exist
I am not quite sure what the problem is, I thought NEW referred the table data was being inserted into?

You could possibly get a list of column names in that table from information_schema views, then use them to create a prepared statement (using cursor to iterate column names) and CONCAT() function to glue together the query string. Then execute the prepared statement.
Seems very contrived even to me, and I'm not sure it would work (and if it did, how efficient it would be)

Set Id to Other column in same table while doing insertQuery

Hi I have a MYSQL table like
PART{
part_id :long,Auto Increment
parent_part_id :long
root_part_id :long
}
I need to do Insert Query on this table where root_part_id should get value of part_id .
In Other cases I know the parent and root part Id . but while doing insertion of root part i need this query. I know there is a option that I should fire a update query after this insert query but I need a solution in a single Query.

You can use a trigger:
DELIMITER $$
CREATE TRIGGER `before_insert_PART`
BEFORE INSERT ON `PART` FOR EACH ROW
BEGIN
SET NEW.root_part_id = NEW.part_id;
END
$$
DELIMITER ;
PS, better use only small characters for your table names. It can lead to OS incompatibilities, on Linux names are case sensitive, and on Windows - not.

How to reset AUTO_INCREMENT in MySQL

How can I reset the AUTO_INCREMENT of a field?
I want it to start counting from 1 again.

You can reset the counter with:
ALTER TABLE tablename AUTO_INCREMENT = 1
For InnoDB you cannot set the auto_increment value lower or equal to the highest current index. (quote from ViralPatel):
Note that you cannot reset the counter to a value less than or equal
to any that have already been used. For MyISAM, if the value is less
than or equal to the maximum value currently in the AUTO_INCREMENT
column, the value is reset to the current maximum plus one. For
InnoDB, if the value is less than the current maximum value in the
column, no error occurs and the current sequence value is not changed.
See How can I reset an MySQL AutoIncrement using a MAX value from another table? on how to dynamically get an acceptable value.

SET #num := 0;
UPDATE your_table SET id = #num := (#num+1);
ALTER TABLE your_table AUTO_INCREMENT =1;

Simply like this:
ALTER TABLE tablename AUTO_INCREMENT = value;
Reference: 13.1.9 ALTER TABLE Statement

There is a very easy way with phpMyAdmin under the "operations" tab. In the table options you can set autoincrement to the number you want.

The best solution that worked for me:
ALTER TABLE my_table MODIFY COLUMN ID INT(10) UNSIGNED;
COMMIT;
ALTER TABLE my_table MODIFY COLUMN ID INT(10) UNSIGNED AUTO_INCREMENT;
COMMIT;
It's fast, works with InnoDB, and I don't need to know the current maximum value!
This way. the auto increment counter will reset and it will start automatically from the maximum value exists.

The highest rated answers to this question all recommend "ALTER yourtable AUTO_INCREMENT= value". However, this only works when value in the alter is greater than the current max value of the autoincrement column. According to the MySQL 8 documentation:
You cannot reset the counter to a value less than or equal to the value that is currently in use. For both InnoDB and MyISAM, if the value is less than or equal to the maximum value currently in the AUTO_INCREMENT column, the value is reset to the current maximum AUTO_INCREMENT column value plus one.
In essence, you can only alter AUTO_INCREMENT to increase the value of the autoincrement column, not reset it to 1, as the OP asks in the second part of the question. For options that actually allow you set the AUTO_INCREMENT downward from its current max, take a look at Reorder / reset auto increment primary key.

As of MySQL 5.6 you can use the simple ALTER TABLE with InnoDB:
ALTER TABLE tablename AUTO_INCREMENT = 1;
The documentation are updated to reflect this:
13.1.7 ALTER TABLE Statement
My testing also shows that the table is not copied. The value is simply changed.

Beware! TRUNCATE TABLE your_table will delete everything in your your_table.
You can also use the syntax TRUNCATE table like this:
TRUNCATE TABLE table_name

ALTER TABLE news_feed DROP id
ALTER TABLE news_feed ADD id BIGINT( 200 ) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (id)
I used this in some of my scripts. The id field is dropped and then added back with previous settings. All the existent fields within the database table are filled in with the new auto increment values. This should also work with InnoDB.
Note that all the fields within the table will be recounted and will have other ids!!!.

It is for an empty table:
ALTER TABLE `table_name` AUTO_INCREMENT = 1;
If you have data, but you want to tidy up it, I recommend to use this:
ALTER TABLE `table_name` DROP `auto_colmn`;
ALTER TABLE `table_name` ADD `auto_colmn` INT( {many you want} ) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (`auto_colmn`);

To update to the latest plus one id:
ALTER TABLE table_name AUTO_INCREMENT =
(SELECT (id+1) id FROM table_name order by id desc limit 1);
Edit:
SET #latestId = SELECT MAX(id) FROM table_name;
SET #nextId = #latestId + 1;
ALTER TABLE table_name AUTO_INCREMENT = #nextId;
Not tested please test before you run*

Warning: If your column has constraints or is connected as a foreign key to other tables this will have bad effects.
First, drop the column:
ALTER TABLE tbl_name DROP COLUMN column_id
Next, recreate the column and set it as FIRST (if you want it as the first column I assume):
ALTER TABLE tbl_access ADD COLUMN `access_id` int(10) NOT NULL PRIMARY KEY AUTO_INCREMENT FIRST

As of MySQL 5.6 the approach below works faster due to online DDL (note algorithm=inplace):
alter table tablename auto_increment=1, algorithm=inplace;

SET #num := 0;
UPDATE your_table SET id = #num := (#num+1);
ALTER TABLE your_table AUTO_INCREMENT =1;

ALTER TABLE tablename AUTO_INCREMENT = 1

Try to run this query:
ALTER TABLE tablename AUTO_INCREMENT = value;
Or try this query for the reset auto increment
ALTER TABLE `tablename` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL;
And set auto increment and then run this query:
ALTER TABLE `tablename` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT;

The auto-increment counter for a table can be (re)set in two ways:
By executing a query, like others already explained:
ALTER TABLE <table_name> AUTO_INCREMENT=<table_id>;
Using Workbench or another visual database design tool. I am going to show in Workbench how it is done - but it shouldn't be much different in other tools as well. By right clicking over the desired table and choosing Alter table from the context menu. On the bottom you can see all the available options for altering a table. Choose Options and you will get this form:
Then just set the desired value in the field Auto increment as shown in the image. This will basically execute the query shown in the first option.

If you're using PHPStorm's database tool you have to enter this in the database console:
ALTER TABLE <table_name> AUTO_INCREMENT = 0;

I tried to alter the table and set auto_increment to 1 but it did not work. I resolved to delete the column name I was incrementing, then create a new column with your preferred name and set that new column to increment from the onset.

I googled and found this question, but the answer I am really looking for fulfils two criteria:
using purely MySQL queries
reset an existing table auto-increment to max(id) + 1
Since I couldn't find exactly what I want here, I have cobbled the answer from various answers and sharing it here.
Few things to note:
the table in question is InnoDB
the table uses the field id with type as int as primary key
the only way to do this purely in MySQL is to use stored procedure
my images below are using SequelPro as the GUI. You should be able to adapt it based on your preferred MySQL editor
I have tested this on MySQL Ver 14.14 Distrib 5.5.61, for debian-linux-gnu
Step 1: Create Stored Procedure
create a stored procedure like this:
DELIMITER //
CREATE PROCEDURE reset_autoincrement(IN tablename varchar(200))
BEGIN
SET #get_next_inc = CONCAT('SELECT #next_inc := max(id) + 1 FROM ',tablename,';');
PREPARE stmt FROM #get_next_inc;
EXECUTE stmt;
SELECT #next_inc AS result;
DEALLOCATE PREPARE stmt;
set #alter_statement = concat('ALTER TABLE ', tablename, ' AUTO_INCREMENT = ', #next_inc, ';');
PREPARE stmt FROM #alter_statement;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END //
DELIMITER ;
Then run it.
Before run, it looks like this when you look under Stored Procedures in your database.
When I run, I simply select the stored procedure and press Run Selection
Note: the delimiters part are crucial. Hence if you copy and paste from the top selected answers in this question, they tend not to work for this reason.
After I run, I should see the stored procedure
If you need to change the stored procedure, you need to delete the stored procedure, then select to run again.
Step 2: Call the stored procedure
This time you can simply use normal MySQL queries.
call reset_autoincrement('products');
Originally from my own SQL queries notes in https://simkimsia.com/reset-mysql-autoincrement-to-max-id-plus-1/ and adapted for Stack Overflow.

delete from url_rewrite where 1=1;
ALTER TABLE url_rewrite AUTO_INCREMENT = 1;
and then reindex

ALTER TABLE `table_name` DROP `id`;
ALTER TABLE `table_name` ADD `id` INT NOT NULL AUTO_INCREMENT FIRST, ADD PRIMARY KEY (`id`) ;
Shortly,First we deleted id column then added it with primary key id again...

The best way is remove the field with AI and add it again with AI. It works for all tables.

You need to follow the advice from Miles M's comment and here is some PHP code that fixes the range in MySQL. Also you need to open up the my.ini file (MySQL) and change max_execution_time=60 to max_execution_time=6000; for large databases.
Don’t use "ALTER TABLE tablename AUTO_INCREMENT = 1". It will delete everything in your database.
$con = mysqli_connect($dbhost, $dbuser, $dbpass, $database);
$res = mysqli_query($con, "select * FROM data WHERE id LIKE id ORDER BY id ASC");
$count = 0;
while ($row = mysqli_fetch_array($res)){
$count++;
mysqli_query($con, "UPDATE data SET id='".$count."' WHERE id='".$row['id']."'");
}
echo 'Done reseting id';
mysqli_close($con);

I suggest you to go to Query Browser and do the following:
Go to schemata and find the table you want to alter.
Right click and select copy create statement.
Open a result tab and paste the create statement their.
Go to the last line of the create statement and look for the Auto_Increment=N,
(Where N is a current number for auto_increment field.)
Replace N with 1.
Press Ctrl + Enter.
Auto_increment should reset to one once you enter a new row in the table.
I don't know what will happen if you try to add a row where an auto_increment field value already exist.

User-defined Table Variables in MySQL 5.5?

I've recently moved from MSSQL to MySQL.
I would like to use a table variable (or equivalent) inside a MySQL 5.5 stored routine, to populate a dataset for an online report.
In MS SQL, I would do it this way
...
...
DECLARE #tblName TABLE
WHILE <condition>
BEGIN
Insert Row based on iteration value
END
...
...
From what I understand, I can't declare table variables in MySQL (correct me if I'm wrong) How do I implement the above logic in a MySQL stored procedure?

You could create a table or temporary table and populate it with data you need.
CREATE TABLE Syntax

You understand that limitation correctly. The MySQL user manual clearly states that user-defined variables cannot refer to a table:
http://dev.mysql.com/doc/refman/5.5/en/user-variables.html
User variables are intended to provide data values. They cannot be used directly in an SQL statement as an identifier or as part of an identifier, such as in contexts where a table or database name is expected, or as a reserved word such as SELECT.

create temporary table tmp
(
id int unsigned not null,
name varchar(32) not null
)
engine=memory; -- change engine type if required e.g myisam/innodb
insert into tmp (id, name) select id, name from foo... ;
-- do more work...
select * from tmp order by id;
drop temporary table if exists tmp;

I think this covers it. Also, this may be helpful.