MySQL stored procedure insert multiple rows from list - mysql

Question

How can I write a MySQL stored procedure to insert values from a variable sized list? More specifically I need to insert data into one parent table, get the ID from the insert, and then insert a variable number of child records along with the new ID into another table in a one-to-many relationship. My schema looks something like this:
TableA:
table_a_id -- Auto Increment
counter
some_data...
TableB:
table_b_id -- Auto Increment
table_a_id -- Foreign Key Constraint
some_data_from_list...
My stored procedure so far looks like this:
DELIMITER ;;
CREATE PROCEDURE insert_group_alert(
IN _some_data_a VARCHAR(255),
IN _data_list_b TEXT,
)
BEGIN
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
ROLLBACK;
END;
START TRANSACTION;
INSERT INTO TableA (
some_data,
counter
)
VALUES (
_some_data_a,
1
)
ON DUPLICATE KEY UPDATE
counter = counter + 1;
SELECT last_insert_id()
INTO #newId;
LIST INSERT ???:
INSERT INTO TableB (
table_a_id, some_data
) VALUES (
#newId,
list_item,
);
END LIST INSERT ???
COMMIT;
END ;;
DELIMITER ;
My thought was to pass in a list of items to insert into table B via a comma delimited string. The values are strings. I am not sure what to do in the LIST INSERT section. Do I need a loop of some sort? Is this stored procedure I have so far the correct way to do this? I don't want to do a batch as I could potentially have hundreds or even thousands of items in the list. Is there a better solution? I am using straight JDBC.

Answer 1

Yes, you need a loop, in which you can use substring_index() to get the values within the list. The solution is based on the answers from this SO topic:
DELIMITER ;;
CREATE PROCEDURE insert_group_alert(
IN _some_data_a VARCHAR(255),
IN _data_list_b TEXT,
)
BEGIN
DECLARE strLen INT DEFAULT 0;
DECLARE SubStrLen INT DEFAULT 0;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
ROLLBACK;
END;
START TRANSACTION;
INSERT INTO TableA (
some_data,
counter
)
VALUES (
_some_data_a,
1
) -- you do not really need this, since you do not provide an id
ON DUPLICATE KEY UPDATE
counter = counter + 1;
SELECT last_insert_id()
INTO #newId;
do_this:
LOOP
SET strLen = CHAR_LENGTH(_data_list_b);
INSERT INTO TableB (table_a_id, some_data) VALUES(#newId,SUBSTRING_INDEX(_data_list_b, ',', 1));
SET SubStrLen = CHAR_LENGTH(SUBSTRING_INDEX(_data_list_b, ',', 1))+2;
SET _data_list_b = MID(_data_list_b, SubStrLen, strLen); --cut the 1st list item out
IF _data_list_b = '' THEN
LEAVE do_this;
END IF;
END LOOP do_this;
COMMIT;
END ;;
DELIMITER ;