Question

here’s what I’d like to do in mySQL… I’m getting the feeling that this is simply not feasible, but would love to be wrong…

create procedure foo(IN MYTABLE varchar(50) , IN COLNAME varchar (50), IN MYTYPE varchar(50))  begin  IF (select count(*) from information_schema.columns where table_name =MYTABLE and column_name = COLNAME) = 0  THEN alter table MYTABLE add column MYNAME MYTYPE;  end;  call foo( 'table_foo' , 'column_bar' , 'varchar(100)' ); 

Answer 1

Don’t know why on Earth you would want it, but it’s possible:

DELIMITER // DROP PROCEDURE foo// CREATE PROCEDURE foo(IN MYTABLE varchar(50) , IN COLNAME varchar (50), IN MYTYPE varchar(50)) BEGIN   SET @ddl = CONCAT('alter table ', MYTABLE, ' add column (', COLNAME, ' ', MYTYPE, ')');   PREPARE STMT FROM @ddl;   EXECUTE STMT; END; //