Truncate all tables in a MySQL database in one com

Question

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.

Answer 1

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

Answer 2

1. 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).
2. So, all foreign key constraints must be dropped initially followed by table truncation.
3. Optionally, use the optimize table (in mysql, innodb engine esp) to reclaim the used data space/size to OS after data truncation.

4. 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.

Answer 3

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

Answer 4

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');

Answer 5

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

Answer 6

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