- 12.1 Data Definition Statements
- 12.1.1 ALTER DATABASE Syntax
- 12.1.2 ALTER EVENT Syntax
- 12.1.3 ALTER FUNCTION Syntax
- 12.1.4 ALTER PROCEDURE Syntax
- 12.1.5 ALTER SERVER Syntax
- 12.1.6 ALTER TABLE Syntax
- 12.1.7 ALTER VIEW Syntax
- 12.1.8 CREATE DATABASE Syntax
- 12.1.9 CREATE EVENT Syntax
- 12.1.10 CREATE FUNCTION Syntax
- 12.1.11 CREATE INDEX Syntax
- 12.1.12 CREATE PROCEDURE and CREATE FUNCTION Syntax
- 12.1.13 CREATE SERVER Syntax
- 12.1.14 CREATE TABLE Syntax
- 12.1.15 CREATE TRIGGER Syntax
- 12.1.16 CREATE VIEW Syntax
- 12.1.17 DROP DATABASE Syntax
- 12.1.18 DROP EVENT Syntax
- 12.1.19 DROP FUNCTION Syntax
- 12.1.20 DROP INDEX Syntax
- 12.1.21 DROP PROCEDURE and DROP FUNCTION Syntax
- 12.1.22 DROP SERVER Syntax
- 12.1.23 DROP TABLE Syntax
- 12.1.24 DROP TRIGGER Syntax
- 12.1.25 DROP VIEW Syntax
- 12.1.26 RENAME TABLE Syntax
DROP [TEMPORARY] TABLE [IF EXISTS]
tbl_name [, tbl_name] ...
[RESTRICT | CASCADE]
DROP TABLE removes one or more
tables. You must have the DROP
privilege for each table. All table data and the table definition
are removed, so be
careful with this statement! If any of the tables named
in the argument list do not exist, MySQL returns an error
indicating by name which nonexisting tables it was unable to drop,
but it also drops all of the tables in the list that do exist.
Important
When a table is dropped, user privileges on the table are
not automatically dropped. See
Section 12.4.1.3, “GRANT Syntax”.
Note that for a partitioned table, DROP
TABLE permanently removes the table definition, all of
its partitions, and all of the data which was stored in those
partitions. It also removes the partitioning definition
(.par) file associated with the dropped
table.
Use IF EXISTS to prevent an error from
occurring for tables that do not exist. A NOTE
is generated for each nonexistent table when using IF
EXISTS. See Section 12.4.5.41, “SHOW WARNINGS Syntax”.
RESTRICT and CASCADE are
allowed to make porting easier. In MySQL 5.4, they do
nothing.
Note
DROP TABLE automatically commits
the current active transaction, unless you use the
TEMPORARY keyword.
The TEMPORARY keyword has the following
effects:
The statement drops only
TEMPORARYtables.The statement does not end an ongoing transaction.
No access rights are checked. (A
TEMPORARYtable is visible only to the session that created it, so no check is necessary.)
Using TEMPORARY is a good way to ensure that
you do not accidentally drop a non-TEMPORARY
table.
User Comments
An example to drop tables having parent-child relationship is to drop the child tables first and then the parent tables. This can be very helpful when we drop tables and then recreate them in a script.
Example:
Let's say table A has two children B and C. Then we can use the following syntax to drop all tables.
DROP TABLE IF EXISTS B,C,A;
This can be placed in the beginning of the script instead
of individually dropping each table (somewhat but not exactly similar to CASCADE CONSTRAINTS option in Oracle).
Just found an excellent library, which allows dropping multiple tables using syntax similar to "drop table like 'sales%'". The library can also do some multi-purpose Dynamic SQL.
You can read about the specific syntax at: http://datacharmer.blogspot.com/2005/12/mysql-5-general-purpose-routine.html
It can be downloaded from https://sourceforge.net/project/showfiles.php?group_id=166288
Guy, "drop tables like" could be realized thus:
delimiter $$
create procedure drop_tables_like(pattern varchar(255), db varchar(255))
begin
select @str_sql:=concat('drop table ', group_concat(table_name))
from information_schema.tables
where table_schema=db and table_name like pattern;
prepare stmt from @str_sql;
execute stmt;
drop prepare stmt;
end$$
call drop_tables_like('kw_%', 'db_1')$$
drop procedure if exists drop_tables_like$$
delimiter ;
It's also possible to do DROP TABLE LIKE 'tableprefix%' using the free software maatkit tool from http://www.maatkit.org/
Example:
mk-find --dblike "dbname" --tbllike "tableprefix%" --exec_plus "DROP TABLE %s"
To drop ALL tables in your database (fill out the first line as appropriate):
MYSQL="mysql -h HOST -u USERNAME -pPASSWORD -D DB_NAME"
$MYSQL -BNe "show tables" | awk '{print "set foreign_key_checks=0; drop table `" $1 "`;"}' | $MYSQL
unset MYSQL
This can be useful if you need to empty a database in order to restore a backup made by mysqldump, but you couldn't use --add-drop-database because you don't have CREATE DATABASE privileges on the command line (e.g. you're on shared hosting). mysqldump adds DROP TABLE by default, but if tables may have been added or renamed since the time of your backup (e.g. by some sort of update process that you're trying to revert from), failing to drop those tables will likely cause serious headaches later on.
Of course this raises the question of why MySQL doesn't support "DROP TABLE *;" (in which case mysqldump could just insert that)?
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