Execute the result of a sql select in MySql

问题

I am trying to get MySql to execute the result of the below statement as further sql statements. I believe in oracle sqlplus this is achieved using the spool function. How is this achieved in Mysql?

select concat('OPTIMIZE TABLE `', ist.TABLE_SCHEMA,'`.',  ist.TABLE_NAME, ';') FROM INFORMATION_SCHEMA.TABLES ist where table_schema = 'my_schema';

回答1:

You have to use prepared statements.

SET @s:='';
SELECT @s:=concat(@s, 'OPTIMIZE TABLE `', ist.TABLE_SCHEMA,'`.',  ist.TABLE_NAME, ';') FROM INFORMATION_SCHEMA.TABLES ist where table_schema = 'my_schema';    
PREPARE stmt FROM @s;
EXECUTE stmt;

DEALLOCATE PREPARE stmt;

But you have to put all the optimize table statements into one variable, that's why I'm concatenating @s with itself. Else you'd have to work with a cursor, which is unnecessary work.

As of MySQL 5.0.23, the following additional statements are supported:

ANALYZE TABLE
OPTIMIZE TABLE
REPAIR TABLE

EDIT: An even simpler approach is this:

SELECT CONCAT('OPTIMIZE TABLE `', ist.TABLE_SCHEMA,'`.',  ist.TABLE_NAME, ';') FROM INFORMATION_SCHEMA.TABLES ist WHERE table_schema = 'my_schema'
INTO OUTFILE '/tmp/my_optimization';
SOURCE 'tmp/my_optimization';

回答2:

If you are accessing it via the mysql command line client you could just pipe the output of the first command into the cli tool again.

mysql --batch --silent -nBe "select concat('OPTIMIZE TABLE `', ist.TABLE_SCHEMA,'`.',  ist.TABLE_NAME, ';') FROM INFORMATION_SCHEMA.TABLES ist where table_schema = 'my_schema'" | mysql my_schema

来源：https://stackoverflow.com/questions/16012630/execute-the-result-of-a-sql-select-in-mysql

标签

mysql

command-line