Is there a nice easy way to drop all tables from a MySQL database, ignoring any foreign key constraints that may be in there?
I found the generated set of drop statements useful, and recommend these tweaks:
- Limit the generated drops to your database like this:
SELECT concat('DROP TABLE IF EXISTS `', table_name, '`;')
FROM information_schema.tables
WHERE table_schema = 'MyDatabaseName';
Note: This does not execute the DROP statements, it just gives you a list of them. You will need to cut and paste the output into your SQL engine to execute them.
- Note, per http://dev.mysql.com/doc/refman/5.5/en/drop-table.html, dropping with cascade is pointless / misleading:
"RESTRICT and CASCADE are permitted to make porting easier. In MySQL 5.5, they do nothing."
Therefore, in order for the drop statements to work if you need:
SET FOREIGN_KEY_CHECKS = 0
This will disable referential integrity checks - so when you are done performing the drops you need, you will want to reset key checking with
SET FOREIGN_KEY_CHECKS = 1
- The final execution should look like:
SET FOREIGN_KEY_CHECKS = 0;
-- Your semicolon separated list of DROP statements here
SET FOREIGN_KEY_CHECKS = 1;
NB: to use output of SELECT easier, mysql -B option can help.
From http://www.devdaily.com/blog/post/mysql/drop-mysql-tables-in-any-order-foreign-keys:
SET FOREIGN_KEY_CHECKS = 0;
drop table if exists customers;
drop table if exists orders;
drop table if exists order_details;
SET FOREIGN_KEY_CHECKS = 1;
(Note that this answers how to disable foreign key checks in order to be able to drop the tables in arbitrary order. It does not answer how to automatically generate drop-table statements for all existing tables and execute them in a single script. Jean's answer does.)
Here is SurlyDre's stored procedure modified so that foreign keys are ignored:
DROP PROCEDURE IF EXISTS `drop_all_tables`;
DELIMITER $$
CREATE PROCEDURE `drop_all_tables`()
BEGIN
DECLARE _done INT DEFAULT FALSE;
DECLARE _tableName VARCHAR(255);
DECLARE _cursor CURSOR FOR
SELECT table_name
FROM information_schema.TABLES
WHERE table_schema = SCHEMA();
DECLARE CONTINUE HANDLER FOR NOT FOUND SET _done = TRUE;
SET FOREIGN_KEY_CHECKS = 0;
OPEN _cursor;
REPEAT FETCH _cursor INTO _tableName;
IF NOT _done THEN
SET @stmt_sql = CONCAT('DROP TABLE ', _tableName);
PREPARE stmt1 FROM @stmt_sql;
EXECUTE stmt1;
DEALLOCATE PREPARE stmt1;
END IF;
UNTIL _done END REPEAT;
CLOSE _cursor;
SET FOREIGN_KEY_CHECKS = 1;
END$$
DELIMITER ;
call drop_all_tables();
DROP PROCEDURE IF EXISTS `drop_all_tables`;
every approach above includes a lot more work than this one AFAICT...
( mysqldump --add-drop-table --no-data -u root -p database | grep 'DROP TABLE' ) > ./drop_all_tables.sql
mysql -u root -p database < ./drop_all_tables.sql
From this answer,
execute:
use `dbName`; --your db name here
SET FOREIGN_KEY_CHECKS = 0;
SET @tables = NULL;
SET GROUP_CONCAT_MAX_LEN=32768;
SELECT GROUP_CONCAT('`', table_schema, '`.`', table_name, '`') INTO @tables
FROM information_schema.tables
WHERE table_schema = (SELECT DATABASE());
SELECT IFNULL(@tables, '') INTO @tables;
SET @tables = CONCAT('DROP TABLE IF EXISTS ', @tables);
PREPARE stmt FROM @tables;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET FOREIGN_KEY_CHECKS = 1;
This drops tables from the database currently in use. You can set current database using use.
Or otherwise, Dion's accepted answer is simpler, except you need to execute it twice, first to get the query, and second to execute the query. I provided some silly back-ticks to escape special characters in db and table names.
SELECT CONCAT('DROP TABLE IF EXISTS `', table_schema, '`.`', table_name, '`;')
FROM information_schema.tables
WHERE table_schema = 'dbName'; --your db name here
Here's a cursor based solution. Kinda lengthy but works as a single SQL batch:
DROP PROCEDURE IF EXISTS `drop_all_tables`;
DELIMITER $$
CREATE PROCEDURE `drop_all_tables`()
BEGIN
DECLARE _done INT DEFAULT FALSE;
DECLARE _tableName VARCHAR(255);
DECLARE _cursor CURSOR FOR
SELECT table_name
FROM information_schema.TABLES
WHERE table_schema = SCHEMA();
DECLARE CONTINUE HANDLER FOR NOT FOUND SET _done = TRUE;
OPEN _cursor;
REPEAT FETCH _cursor INTO _tableName;
IF NOT _done THEN
SET @stmt_sql = CONCAT('DROP TABLE ', _tableName);
PREPARE stmt1 FROM @stmt_sql;
EXECUTE stmt1;
DEALLOCATE PREPARE stmt1;
END IF;
UNTIL _done END REPEAT;
CLOSE _cursor;
END$$
DELIMITER ;
call drop_all_tables();
DROP PROCEDURE IF EXISTS `drop_all_tables`;
You can do:
select concat('drop table if exists ', table_name, ' cascade;')
from information_schema.tables;
Then run the generated queries. They will drop every single table on the current database.
Here is some help on drop table command.
I came up with this modification on Dion Truter's answer to make it easier with many tables:
SET GROUP_CONCAT_MAX_LEN = 10000000;
SELECT CONCAT('SET FOREIGN_KEY_CHECKS=0;\n',
GROUP_CONCAT(CONCAT('DROP TABLE IF EXISTS `', table_name, '`')
SEPARATOR ';\n'),
';\nSET FOREIGN_KEY_CHECKS=1;')
FROM information_schema.tables
WHERE table_schema = 'SchemaName';
This returns the entire thing in one field, so you can copy once and delete all the tables (use Copy Field Content (unquoted) in Workbench). If you have a LOT of tables, you may hit some limits on GROUP_CONCAT(). If so, increase the max len variable (and max_allowed_packet, if necessary).
A one liner to drop all tables from a given database:
echo "DATABASE_NAME"| xargs -I{} sh -c "mysql -Nse 'show tables' {}| xargs -I[] mysql -e 'SET FOREIGN_KEY_CHECKS=0; drop table []' {}"
Running this will drop all tables from database DATABASE_NAME.
And a nice thing about this is that the database name is only written explicitly once.
Here is an automated way to do this via a bash script:
host=$1
dbName=$2
user=$3
password=$4
if [ -z "$1" ]
then
host="localhost"
fi
# drop all the tables in the database
for i in `mysql -u$user -p$password $dbName -e "show tables" | grep -v Tables_in` ; do echo $i && mysql -u$user -p$password $dbName -e "SET FOREIGN_KEY_CHECKS = 0; drop table $i ; SET FOREIGN_KEY_CHECKS = 1" ; done
If in linux (or any other system that support piping, echo and grep) you can do it with one line:
echo "SET FOREIGN_KEY_CHECKS = 0;" > temp.txt; \
mysqldump -u[USER] -p[PASSWORD] --add-drop-table --no-data [DATABASE] | grep ^DROP >> temp.txt; \
echo "SET FOREIGN_KEY_CHECKS = 1;" >> temp.txt; \
mysql -u[USER] -p[PASSWORD] [DATABASE] < temp.txt;
I know this is an old question, but I think this method is fast and simple.
Googling on topic always brings me to this SO question so here is working mysql code that deletes BOTH tables and views:
DROP PROCEDURE IF EXISTS `drop_all_tables`;
DELIMITER $$
CREATE PROCEDURE `drop_all_tables`()
BEGIN
DECLARE _done INT DEFAULT FALSE;
DECLARE _tableName VARCHAR(255);
DECLARE _cursor CURSOR FOR
SELECT table_name
FROM information_schema.TABLES
WHERE table_schema = SCHEMA();
DECLARE CONTINUE HANDLER FOR NOT FOUND SET _done = TRUE;
SET FOREIGN_KEY_CHECKS = 0;
OPEN _cursor;
REPEAT FETCH _cursor INTO _tableName;
IF NOT _done THEN
SET @stmt_sql1 = CONCAT('DROP TABLE IF EXISTS ', _tableName);
SET @stmt_sql2 = CONCAT('DROP VIEW IF EXISTS ', _tableName);
PREPARE stmt1 FROM @stmt_sql1;
PREPARE stmt2 FROM @stmt_sql2;
EXECUTE stmt1;
EXECUTE stmt2;
DEALLOCATE PREPARE stmt1;
DEALLOCATE PREPARE stmt2;
END IF;
UNTIL _done END REPEAT;
CLOSE _cursor;
SET FOREIGN_KEY_CHECKS = 1;
END$$
DELIMITER ;
call drop_all_tables();
DROP PROCEDURE IF EXISTS `drop_all_tables`;
In php its as easy as:
$pdo = new PDO('mysql:dbname=YOURDB', 'root', 'root');
$pdo->exec('SET FOREIGN_KEY_CHECKS = 0');
$query = "SELECT concat('DROP TABLE IF EXISTS ', table_name, ';')
FROM information_schema.tables
WHERE table_schema = 'YOURDB'";
foreach($pdo->query($query) as $row) {
$pdo->exec($row[0]);
}
$pdo->exec('SET FOREIGN_KEY_CHECKS = 1');
Just remember to change YOURDB to the name of your database, and obviously the user/pass.
In a Linux shell like bash/zsh:
DATABASE_TO_EMPTY="your_db_name";
{ echo "SET FOREIGN_KEY_CHECKS = 0;" ; \
mysql "$DATABASE_TO_EMPTY" --skip-column-names -e \
"SELECT concat('DROP TABLE IF EXISTS ', table_name, ';') \
FROM information_schema.tables WHERE table_schema = '$DATABASE_TO_EMPTY';";\
} | mysql "$DATABASE_TO_EMPTY"
This will generate the commands, then immediately pipe them to a 2nd client instance which will delete the tables.
The clever bit is of course copied from other answers here - I just wanted a copy-and-pasteable one-liner (ish) to actually do the job the OP wanted.
Note of course you'll have to put your credentials in (twice) in these mysql commands, too, unless you have a very low security setup. (or you could alias your mysql command to include your creds.)
Just put here some useful comment made by Jonathan Watt to drop all tables
MYSQL="mysql -h HOST -u USERNAME -pPASSWORD DB_NAME"
$MYSQL -BNe "show tables" | awk '{print "set foreign_key_checks=0; drop table `" $1 "`;"}' | $MYSQL
unset MYSQL
It helps me and I hope it could be useful
This is a pretty old post, but none of the answers here really answered the question in my opinion, so I hope my post will help people!
I found this solution on another question that works really well for me:
mysql -Nse 'show tables' DB_NAME | while read table; do mysql -e "SET FOREIGN_KEY_CHECKS=0; truncate table \`$table\`" DB_NAME; done
That will actually empty all your tables in the database DB_NAME, and not only display the TRUNCATE command line.
Hope this helps!
Building on the answer by @Dion Truter and @Wade Williams, the following shell script will drop all tables, after first showing what it is about to run, and giving you a chance to abort using Ctrl-C.
#!/bin/bash
DB_HOST=xxx
DB_USERNAME=xxx
DB_PASSWORD=xxx
DB_NAME=xxx
CMD="mysql -sN -h ${DB_HOST} -u ${DB_USERNAME} -p${DB_PASSWORD} ${DB_NAME}"
# Generate the drop statements
TMPFILE=/tmp/drop-${RANDOM}.sql
echo 'SET FOREIGN_KEY_CHECKS = 0;' > ${TMPFILE}
${CMD} $@ >> ${TMPFILE} << ENDD
SELECT concat('DROP TABLE IF EXISTS \`', table_name, '\`;')
FROM information_schema.tables
WHERE table_schema = '${DB_NAME}';
ENDD
echo 'SET FOREIGN_KEY_CHECKS = 1;' >> ${TMPFILE}
# Warn what we are about to do
echo
cat ${TMPFILE}
echo
echo "Press ENTER to proceed (or Ctrl-C to abort)."
read
# Run the SQL
echo "Dropping tables..."
${CMD} $@ < ${TMPFILE}
echo "Exit status is ${?}."
rm ${TMPFILE}
This solution is based on @SkyLeach answer but with the support of dropping tables with foreign keys.
echo "SET FOREIGN_KEY_CHECKS = 0;" > ./drop_all_tables.sql
mysqldump --add-drop-table --no-data -u user -p dbname | grep 'DROP TABLE' >> ./drop_all_tables.sql
echo "SET FOREIGN_KEY_CHECKS = 1;" >> ./drop_all_tables.sql
mysql -u user -p dbname < ./drop_all_tables.sql
DB="your database name" \
&& mysql $DB < "SET FOREIGN_KEY_CHECKS=0" \
&& mysqldump --add-drop-table --no-data $DB | grep 'DROP TABLE' | grep -Ev "^$" | mysql $DB \
&& mysql $DB < "SET FOREIGN_KEY_CHECKS=1"
Simple and clear (may be).
Might not be a fancy solution, but this worked me and saved my day.
Worked for Server version: 5.6.38 MySQL Community Server (GPL)
Steps I followed:
1. generate drop query using concat and group_concat.
2. use database
3. disable key constraint check
4. copy the query generated from step 1
5. enable key constraint check
6. run show table
MySQL shell
mysql> SYSTEM CLEAR;
mysql> SELECT CONCAT('DROP TABLE IF EXISTS `', GROUP_CONCAT(table_name SEPARATOR '`, `'), '`;') AS dropquery FROM information_schema.tables WHERE table_schema = 'emall_duplicate';
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| dropquery |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| DROP TABLE IF EXISTS `admin`, `app`, `app_meta_settings`, `commission`, `commission_history`, `coupon`, `email_templates`, `infopages`, `invoice`, `m_pc_xref`, `member`, `merchant`, `message_templates`, `mnotification`, `mshipping_address`, `notification`, `order`, `orderdetail`, `pattributes`, `pbrand`, `pcategory`, `permissions`, `pfeatures`, `pimage`, `preport`, `product`, `product_review`, `pspecification`, `ptechnical_specification`, `pwishlist`, `role_perms`, `roles`, `settings`, `test`, `testanother`, `user_perms`, `user_roles`, `users`, `wishlist`; |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> USE emall_duplicate;
Database changed
mysql> SET FOREIGN_KEY_CHECKS = 0; Query OK, 0 rows affected (0.00 sec)
// copy and paste generated query from step 1
mysql> DROP TABLE IF EXISTS `admin`, `app`, `app_meta_settings`, `commission`, `commission_history`, `coupon`, `email_templates`, `infopages`, `invoice`, `m_pc_xref`, `member`, `merchant`, `message_templates`, `mnotification`, `mshipping_address`, `notification`, `order`, `orderdetail`, `pattributes`, `pbrand`, `pcategory`, `permissions`, `pfeatures`, `pimage`, `preport`, `product`, `product_review`, `pspecification`, `ptechnical_specification`, `pwishlist`, `role_perms`, `roles`, `settings`, `test`, `testanother`, `user_perms`, `user_roles`, `users`, `wishlist`;
Query OK, 0 rows affected (0.18 sec)
mysql> SET FOREIGN_KEY_CHECKS = 1;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW tables;
Empty set (0.01 sec)
mysql>
I use the following with a MSSQL server:
if (DB_NAME() = 'YOUR_DATABASE')
begin
while(exists(select 1 from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where CONSTRAINT_TYPE='FOREIGN KEY'))
begin
declare @sql nvarchar(2000)
SELECT TOP 1 @sql=('ALTER TABLE ' + TABLE_SCHEMA + '.[' + TABLE_NAME + '] DROP CONSTRAINT [' + CONSTRAINT_NAME + ']')
FROM information_schema.table_constraints
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'
exec (@sql)
PRINT @sql
end
while(exists(select 1 from INFORMATION_SCHEMA.TABLES))
begin
declare @sql2 nvarchar(2000)
SELECT TOP 1 @sql2=('DROP TABLE ' + TABLE_SCHEMA + '.[' + TABLE_NAME + ']')
FROM INFORMATION_SCHEMA.TABLES
exec (@sql2)
PRINT @sql2
end
end
else
print('Only run this script on the development server!!!!')
Replace YOUR_DATABASE with the name of your database or remove the entire IF statement (I like the added safety).
Best solution for me so far
Select Database -> Right Click -> Tasks -> Generate Scripts - will open wizard for generating scripts. After choosing objects in set Scripting option click Advanced Button. Under "Script DROP and CREATE" select Script DROP.
Run script.
来源：https://stackoverflow.com/questions/3476765/mysql-drop-all-tables-ignoring-foreign-keys