Mysql calling procedure failed when dynamically alter table in it

Question

I want to alter my tables dynamically based on whether the table has specific column.

My database name is summer_cms, and there are over 50 tables in it.

Answer 1

Here's an example of dynamic sql

drop procedure if exists alter_table;
delimiter //

CREATE DEFINER=`root`@`localhost`  procedure alter_table()

begin
declare tablename varchar(20);
set tablename = 'u';

set @sqlstmt =  concat('ALTER TABLE ', tableName, ' ADD COLUMN ', char(96), 'add_user_id', char(96), ' INT NOT NULL DEFAULT 0 COMMENT', char(39), 'add user id', char(39),';');
prepare stmt from @sqlstmt;
execute stmt;
deallocate prepare stmt;

end //

delimiter ;

Note I have used ascii backticks and single quotes.