Creating stored procedure for multiple insert and alter table queries - php

Question

$link->query("DROP TABLE IF EXISTS table2");
$link->query("CREATE TABLE table2 (newcol BIGINT UNSIGNED PRIMARY KEY)");
$result=$link->query("select col1 from table1");
while($data=$result->fetch_array(MYSQL_ASSOC))
{
$link->query("insert into table2 (newcol) values($data['col1']);
$link->query(""ALTER TABLE table2 ADD `".$data['col1']."` BIGINT DEFAULT 0"");
}
What Iam trying to do is
Create a table "table2" with one column "newcol".
select all the values of "col1" from "table1" And
for each value of col1 from table1
-insert the value into "newcol" of table2 And
-add a column named (value from col1 of table 1) into "table2"
The above code looks very neat and efficient in php , but the problem is it takes some amount of time .So I think its better to convert these into MySQL Stored procedure .Since I'm new to stored procedures , very much confused .Please help me guys.

Answer 1

Of course, I couldn't test it, but it is compiling fine on on my computer.
DELIMITER //
CREATE PROCEDURE `myProcedure` ()
BEGIN
DECLARE _done BOOLEAN DEFAULT FALSE;
DECLARE _myField BIGINT UNSIGNED DEFAULT 0;
/* the cursor here is like your PDOStatement
* it is used to fetch data */
DEClARE _myReader CURSOR FOR
SELECT `col1` FROM `table1`;
/* it is not very elegant, but we need to throw an exception
* to break the loop */
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET _done = TRUE;
DROP TABLE IF EXISTS `table2`;
CREATE TABLE `table2` (
`newcol` BIGINT UNSIGNED PRIMARY KEY
);
/* you open your PDOStatement */
OPEN _myReader;
/* myLoop is like a GOTO*/
myLoop: LOOP
/* $result->fetch_array(MYSQL_ASSOC)*/
FETCH _myReader INTO _myField;
/* if the no data exception had been thrown,
* goto the end of the loop */
IF _done = 1 THEN
LEAVE myLoop;
END IF;
INSERT INTO `table2` (newcol) VALUES (_myField);
ALTER TABLE `table2` ADD `_myField` BIGINT DEFAULT 0;
END LOOP myLoop;
/* close your PDO object */
CLOSE _myReader;
END //

Answer 2

Jonathan Parent Lévesque helped me a lot in figuring out how the looping inside stored procedures work and to get the overall structure for the stored procedure equivalent to the php code described in the question above.
Thanks Jonathan Parent Lévesque
But in his code Adding column name using a variable didn't work as expected.
Finally I figured it out
BEGIN
DECLARE _done BOOLEAN DEFAULT FALSE;
DECLARE _myField BIGINT DEFAULT 0;
DEClARE _myReader CURSOR FOR
SELECT id FROM `tags`;
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET _done = TRUE;
DROP TABLE IF EXISTS `tag_similarity`;
CREATE TABLE `tag_similarity` (
`tag` BIGINT UNSIGNED PRIMARY KEY
);
OPEN _myReader;
myLoop: LOOP
FETCH _myReader INTO _myField;
IF _done = 1 THEN
LEAVE myLoop;
END IF;
INSERT INTO `tag_similarity` (tag) VALUES (_myField);
SET #sql = CONCAT('ALTER TABLE tag_similarity ADD `',_myfield,'` BIGINT DEFAULT 0');
PREPARE stmt FROM #sql;
EXECUTE stmt ;
DEALLOCATE PREPARE stmt;
END LOOP myLoop;
CLOSE _myReader;
END