4

I made this 'simple' code:
set @a=null,@c=null,@b=concat("show tables where",ifnull(concat(" `Tables_in_",database(),"` like '",@c,"' and"),'')," (@a:=concat_ws(',',@a,`Tables_in_",database(),"`))");
Prepare `bd` from @b;
EXECUTE `bd`;
DEALLOCATE PREPARE `bd`;
set @a:=concat('optimize table ',...