Delete data from all tables in MYSQL

The most robust way to clear all tables in a database was submitted by kostanos in How to remove all MySQL tables from the command-line without DROP database permissions?

Since the code below clears all tables in the current database you might want to select a different database before you proceed.

USE DATABASE_YOU_WANT_TO_CLEAR;

Following snippet will remove data from the tables even in presence of foreign key constraints. You might also want to double check the list of tables before actual cleanup, just in case if you forgot to select proper database.

-- save current foreign key settings and disable foreign key checks
SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET GROUP_CONCAT_MAX_LEN=32768;  -- you never know how people name their tables
SET @tables = NULL;
SELECT GROUP_CONCAT('`', table_name, '`') INTO @tables
  FROM information_schema.tables
  WHERE table_schema = (SELECT DATABASE());  -- operates on the current DB
SELECT IFNULL(@tables,'dummy') INTO @tables;  -- avoid error if there are no tables

-- At this point you might want to double check the list of tables
-- to be cleared.  Run SELECT @tables; to do so.

SET @tables = CONCAT('DROP TABLE IF EXISTS ', @tables);
PREPARE stmt FROM @tables;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;

In command line...

USE dbname

SET foreign_key_checks = 0;
TRUNCATE tablename;  //do this for each table you want emptied
SET foreign_key_checks = 1;

I don't think so (but I've been wrong before). What I tend to do is those cases is a two-step process.

If your DBMS has a command line interface, you can use it to create a script to do the bulk of the work, something like:

db2 "select 'db2 delete from ' | tblname from sysibm.systables
    where owner = 'pax'" >p2.sh
p2.sh

The first bit simply creates a p2.sh file (or a p2.cmd file under Windows) containing a delete from statement for every table owned by pax. Then you just run that command file to do the dirty work. You may want to check it first, of course :-)

Not the one-step process you were looking for but still very simple. I'm assuming here that mysql also has a command line interface.

Update:

The MySQL version of the above looks like it should be:

echo "select 'mysql truncate table ' | table_name
              from information_schema.tables" | mysql >p2.sh
bash p2.sh

This uses the truncate command which is usually more efficient than delete from for deleting all rows. It also uses the proper MySQL system tables to get the table names.

One point though - you may want to put a where clause on that select to limit the tables to those you want deleted. The query as it stands will try to delete every table. One possibility is to limit it with specific table_schema and/or table_type values.

Easiest method to truncate all tables while retaining schema.

mysqldump -d -uuser -ppass --add-drop-table databasename > databasename.sql

mysql -uuser -ppass databasename < databasename.sql

Not sure if it will retain stored procedures as they are not in use where I work, but I use this regularly to reset databases.

The -d switch on mysqldump means "don't dump data."

The --add-drop-table prepends a DROP TABLE statement to every CREATE TABLE in the dump.