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Comments - SET Variable statement

9 years ago Elena Stepanova
Re: SET Variable statement

CAST only supports a limited number of data types, VARCHAR is not one of them. Please see CAST and CONVERT for more details.

 
9 years ago Chris Isaksen
Re: SET Variable statement

looks like the documentation needs to be corrected

https://mariadb.com/kb/en/mariadb/user-defined-variables/

Clearly shows SET @str = CAST(123 AS VARCHAR(5)); in the docs.

 
9 years ago Elena Stepanova
Re: SET Variable statement

Apparently it was only meant to demonstrate what SET statement looks like, but yes, it was a particularly unfortunate example. I have fixed it now, thanks for noticing.

 
9 years ago Chris Isaksen
Re: SET Variable statement

you wouldn't happen to know the correct syntax for the following:

SET @dbname = 'name'; drop database if exists @dname;

First line works but second doesn't know what @dbname is.

 
9 years ago Elena Stepanova
Re: SET Variable statement [Answer]

You need prepared statements to pull it off. Something like

SET @dbname = 'name';
SET @sql = CONCAT('drop database if exists ', @dbname);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
 
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