How to create a table in memory which is identical to "regular" table? I want a copy without indexes and constraints. Pure SQL (no external tools).
This works (however indexes are created):
create table t_copy (like t_original)
This doesn't:
create table t_copy (like t_original) engine=memory
CREATE TABLE t_copy ENGINE=MEMORY SELECT * FROM t_original;
I actually tried it, it works !!!
mysql> show create table queue\G
*************************** 1. row ***************************
Table: queue
Create Table: CREATE TABLE `queue` (
`ndx` int(11) NOT NULL AUTO_INCREMENT,
`folderid` int(11) NOT NULL,
PRIMARY KEY (`ndx`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1
1 row in set (0.02 sec)
mysql> create table queue_memory engine=MEMORY as select * from queue;
Query OK, 0 rows affected (0.05 sec)<BR>
Records: 0 Duplicates: 0 Warnings: 0<BR>
lwdba#localhost (DB test) :: show create table queue_memory\G
*************************** 1. row ***************************
Table: queue_memory
Create Table: CREATE TABLE `queue_memory` (
`ndx` int(11) NOT NULL DEFAULT '0',
`folderid` int(11) NOT NULL
) ENGINE=MEMORY DEFAULT CHARSET=latin1
1 row in set (0.00 sec)
Give it a try !!!
This should get you an empty table without any indexes.
create table t_copy
select *
from t_original
where 0
To create an in-memory table with the same structure AND indexes as the first table, try:
create table t_copy like t_original;
alter table t_copy engine=mem;
Related
Is it possible to determine if a table was created or already existed when using create table if not exists...?
There seem to be two variables returned:
(query ok, affected_rows)
The query always returns (1, 0) regardless of if the table was created or already existed.
But it seems a create schema if not exists does return affected_rows=1.
Thanks.
I get 1 warning if the table exists (mysql 8.0.25):
mysql> CREATE TABLE IF NOT EXISTS `test` (`id` INT NOT NULL, PRIMARY KEY (`id`));
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE TABLE IF NOT EXISTS `test` (`id` INT NOT NULL, PRIMARY KEY (`id`));
Query OK, 0 rows affected, 1 warning (0.00 sec)
The warning is 1050 Table 'test' already exists
But you can just check if the table exists before creating it
EDIT: it was a bug in or application
What could cause the auto_increment value to jump up billions of values to strike max int?
Our core table uses an int unsigned auto_increment primary key column. Today it skipped every value all the way up to 4294967295.
I was able to resolve this by deleting the offensive row and running
ALTER TABLE [table] AUTO_INCREMENT = [new value];
but I cannot explain how or why it happened.
Our environment is MariaDB 10.2.27 under PHP/Apache.
Any INSERT can specify a high value, and this will implicitly advance the next auto-increment value. In other words, an auto-increment for a table will never be less than the largest value currently inserted in the table, and any client can override the auto-increment mechanism simply by specifying a value in an INSERT.
Demo:
mysql> create table mytable (id int unsigned auto_increment primary key);
mysql> insert into mytable (id) values (DEFAULT);
Query OK, 1 row affected (0.01 sec)
That should have inserted id value 1, so the next AI will be 2:
mysql> show create table mytable\G
*************************** 1. row ***************************
Table: mytable
Create Table: CREATE TABLE `mytable` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4
Now I specify a large value, and the AI is updated accordingly:
mysql> insert into mytable (id) values(1000000000);
Query OK, 1 row affected (0.01 sec)
mysql> show create table mytable\G
*************************** 1. row ***************************
Table: mytable
Create Table: CREATE TABLE `mytable` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1000000001 DEFAULT CHARSET=utf8mb4
Note a value greater than the max unsigned int value 232-1 will be truncated to that value.
mysql> insert into mytable (id) values(1000000000000);
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> show create table mytable\G
*************************** 1. row ***************************
Table: mytable
Create Table: CREATE TABLE `mytable` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4294967295 DEFAULT CHARSET=utf8mb4
So someone must have inserted a large value. Any value larger than 4294967295 will be truncated to 4294967295, and then subsequent inserts that try to use the AI sequence will fail.
I find a correct solution how Load Data Infile in MySQL can work with On Duplicate Key Update. Here is the code I use (get it from stack overflow):
CREATE TEMPORARY TABLE temporary_table LIKE employee_table;
SHOW INDEX FROM temporary_table;
DROP INDEX `PRIMARY` ON temporary_table;
LOAD DATA INFILE 'csv/employee_table'
INTO TABLE temporary_table FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n'
(
`AutoID`, `Name`, `Age`, `Salary`
)
SHOW COLUMNS FROM employee_table;
INSERT INTO employee_table
SELECT * FROM temporary_table
ON DUPLICATE KEY UPDATE AutoID = Values(AutoID);
DROP TEMPORARY TABLE temporary_table;
This code above is working properly to update the table with new records that have different ID only. However, when the PRIMARY key is auto increment (AI), it fails to work. It shows that this below code cannot be run on auto increment PRIMARY key.
DROP INDEX `PRIMARY` ON temporary_table
Here is the error message:
#1075 - Incorrect table definition; there can be only one auto column and it must be defined as a key
I am confused since if I don't use the auto increment, it run perfectly. Anyone know how to fix this problem? Thanks in advance.
there is two procedure.
1) your problem solution.
mysql> DROP INDEX `PRIMARY` ON test5;
ERROR 1075 (42000): Incorrect table definition; there can be only one auto column and it must be defined as a key
mysql> show create table test5;
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test5 | CREATE TEMPORARY TABLE `test5` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`address` varchar(100) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> alter table test5 modify `id` int(11) NOT NULL;
Query OK, 0 rows affected (0.21 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql>
mysql> DROP INDEX `PRIMARY` ON test5;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql>
mysql> show create table test5;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test5 | CREATE TEMPORARY TABLE `test5` (
`id` int(11) NOT NULL,
`name` varchar(50) NOT NULL,
`address` varchar(100) DEFAULT NULL,
UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
2) Best Solution..
we can replace first (two steps) with below single query in the procedure.
1) and 2) we can create new table with same reference structure and without any indexes.
CREATE TEMPORARY TABLE temporary_table SELECT * FROM target_table WHERE 1=0;
Instead of..
1) Create a new temporary table.
CREATE TEMPORARY TABLE temporary_table LIKE target_table;
2) Optionally, drop all indices from the temporary table to speed things up.
SHOW INDEX FROM temporary_table; DROP INDEX PRIMARY ON temporary_table; DROP INDEX some_other_index ON temporary_table;
you can also refer below link.
MySQL LOAD DATA INFILE with ON DUPLICATE KEY UPDATE
I have a table called users in my database. It has a field id of type int. As of now this is manually incremented for every user that registers and some intermediate values are missing because of deleted user accounts. I cannot change the user id of other registered users . I tried to change this column to AUTO_INCREMENT using this statement
ALTER TABLE `userinfo` CHANGE `id` `id` BIGINT(20) NOT NULL AUTO_INCREMENT;
But I got the following error
1062 - ALTER TABLE causes auto_increment resequencing, resulting in
duplicate entry '1' for key 'PRIMARY'
I only have around 200 users in my table. So I wanted to start AUTO_INCREMENT from 201. I executed the following statements
ALTER TABLE `userinfo` AUTO_INCREMENT=201;
ALTER TABLE `userinfo` CHANGE `id` `id` INT(10) NOT NULL AUTO_INCREMENT;
But still I encounter the same issue.
If you don't have duplicates (id), you should not have problems:
mysql> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.7.17 |
+-----------+
1 row in set (0.00 sec)
mysql> DROP TABLE IF EXISTS `userinfo`;
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE TABLE IF NOT EXISTS `userinfo` (
-> `id` INT(11) NOT NULL
-> );
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO `userinfo`
-> (`id`)
-> VALUES
-> (1),
-> (2),
-> (3),
-> -- (1),
-> (10),
-> (11),
-> (15),
-> (20),
-> (182),
-> (191);
Query OK, 9 rows affected (0.00 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE `userinfo`
-> CHANGE `id` `id` BIGINT(20) NOT NULL
-> PRIMARY KEY AUTO_INCREMENT;
Query OK, 9 rows affected (0.00 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE `userinfo` AUTO_INCREMENT = 201;
Query OK, 0 rows affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> SHOW CREATE TABLE `userinfo`\G
*************************** 1. row ***************************
Table: userinfo
Create Table: CREATE TABLE `userinfo` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=201 DEFAULT CHARSET=utf8mb4
1 row in set (0.00 sec)
In another case:
mysql> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.7.17 |
+-----------+
1 row in set (0.00 sec)
mysql> DROP TABLE IF EXISTS `userinfo`;
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE TABLE IF NOT EXISTS `userinfo` (
-> `id` INT(11) NOT NULL
-> );
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO `userinfo`
-> (`id`)
-> VALUES
-> (1),
-> (2),
-> (3),
-> (1), -- Duplicate
-> (10),
-> (11),
-> (15),
-> (20),
-> (182),
-> (191);
Query OK, 10 rows affected (0.00 sec)
Records: 10 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE `userinfo`
-> CHANGE `id` `id` BIGINT(20) NOT NULL
-> PRIMARY KEY AUTO_INCREMENT;
ERROR 1062 (23000): ALTER TABLE causes auto_increment resequencing, resulting in duplicate entry '1' for key 'PRIMARY'
Try resetting the column to primary key, like this:
ALTER TABLE `userinfo` CHANGE `id` `id` INT(10) PRIMARY KEY AUTO_INCREMENT;
You can just drop auto_increment then set auto_increment, do not need recreate primary key
ALTER TABLE `userinfo` CHANGE `id` `id` int NOT NULL;
ALTER TABLE `userinfo` AUTO_INCREMENT=9;
ALTER TABLE `userinfo` CHANGE `id` `id` int NOT NULL AUTO_INCREMENT;
I was having this same problem/error (MySql 5.7.28) with bulk inserts of data that was missing primary key/auto_increment values - even though there were no duplicates. I wanted to preserve the primary key and needed to preserve the original field values also as resequencing would have caused data-integrity problems in the system.
My solution was to remove the auto_increment and then primary key as suggested above:
ALTER TABLE `userinfo` CHANGE `id` `id` int NOT NULL;
ALTER TABLE `userinfo` DROP PRIMARY KEY;
Then run my bulk insert statement without resequencing problems.
Then restore the primary key and original values using the following steps:
renaming the original PK/auto-increment field which now has the desired values in it
creating a new PK/auto-increment field with the original field name
setting the auto-increment value to one more than the max value of the renamed field
copying the original values into the new PK/auto-increment field
dropping the renamed field (now you have the original schema with PK/auto-increment field with original gaps in the sequence as desired.
Here is the sql for the first two steps:
ALTER TABLE `userinfo` CHANGE `id` `orig_id` INT;
ALTER TAble `userinfo` add id int auto_increment not null primary key;
Then use the following query result:
select max(orig_id) + 1 from `userinfo`;
to set the new auto-increment, before updating the new PK/auto-increment values:
ALTER TABLE `userinfo` AUTO_INCREMENT=201;
UPDATE `userinfo` set id = orig_id;
ALTER TABLE `userinfo` drop column orig_id;
and now I've got the original table values copied exactly as wanted. I hope this helps others save time.
There is any procedure to create a table with same structure from another table without data.
i.e table with structure only .at that time i am creating the table with query each time as new database require.
There is any procedure in mysql to create table with structure only with another database table or same database table
please help me
You can use CREATE TABLE LIKE.
CREATE TABLE t1 LIKE t2;
Manual
https://dev.mysql.com/doc/refman/5.7/en/create-table-like.html
Demo
mysql> create table t1(c1 int primary key, c2 int auto_increment, key(c2));
Query OK, 0 rows affected (0.00 sec)
mysql> create table t2 like t1;
Query OK, 0 rows affected (0.01 sec)
mysql> show create table t2;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| t2 | CREATE TABLE `t2` (
`c1` int(11) NOT NULL,
`c2` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`c1`),
KEY `c2` (`c2`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
Try this query Create table like(https://dev.mysql.com/doc/refman/5.7/en/create-table-like.html)
CREATE TABLE table1 LIKE table2;