[mysql] Truncate all tables in a MySQL database in one command?

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.

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.

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.

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'''

<?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 know this isn't exactly one command, but the desired result can be achieved from within phpMyAdmin by following these steps:

1. Select (all) tables to be removed (Check All)
2. Select "Drop" / "Truncate" from the "With selected:" list
3. On the confirmation page ("Do you really want to:") copy the query (everything with the red background)
4. Go at the top and click on SQL and write: "SET FOREIGN_KEY_CHECKS=0;" then paste the previously copied query
5. 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.

mysqldump -u root -p --no-data dbname > schema.sql
mysqldump -u root -p drop dbname
mysqldump -u root -p < schema.sql

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

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"

1. approval_external_system depends on approval_request
2. address depends on customer
3. customer_identification depends on customer
4. external_id depends on customer
5. credential depends on customer
6. email_address depends on customer
7. approval_request depends on customer
8. customer_status depends on customer
9. 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

1. Truncating table address
2. Truncating table approval_external_system
3. Truncating table approval_request
4. Truncating table country
5. Truncating table credential
6. Truncating table customer
7. Truncating table customer_identification
8. Truncating table customer_image
9. 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

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

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`;

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

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;

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.

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

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

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 :-)

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');

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

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

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

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;

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.

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;

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!

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

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

truncate multiple database tables on Mysql instance

SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';') 
FROM INFORMATION_SCHEMA.TABLES where  table_schema in ('db1_name','db2_name');

Use Query Result to truncate tables

Note: may be you will get this error:

ERROR 1217 (23000): 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;