I want to convert game tag data found here into a dimension table of a star schema.
But the problem is that steamspy_tag_data table is organised as such every column name is tag name of a game and one game can have multiple tags. For example, lets say I have game Warcraft3 with appid 30 it would be in a table like this.
appid|strategy|action|shooter|fantasy|
-----+--------+------+-------+-------
30 6345 1452 0 6340
Column value greater than 0 signifies amount of user votes that voted certain game to be of that game tag. For Warcraft3 game with appid 30 - 6345 users voted it classifies as strategy 1452 users it classifies as action, .. etc.
Some columns for example "abstract" (column) tag has almost all 0 throughout the whole column meaning almost no game uses that tag, so to simplify 372 columns with over 29k row value into something more compact I want to run a query that would count non-zero value per every tag column and put them in the new table "tagovi" for better visibility which columns(tags) have relatively low game usage count.
so far I came up with this:
CREATE DEFINER=`root`#`localhost` PROCEDURE `zbroji_tagove`()
BEGIN
DECLARE i INTEGER;
DECLARE total_row_count INTEGER;
DECLARE dummy VARCHAR(255);
DECLARE zbrojeno INTEGER;
DECLARE trenutna VARCHAR(255);
DECLARE kursor CURSOR FOR
SELECT column_name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = 'sppi' AND table_name = 'steamspy_tag_data'
ORDER BY ordinal_position;
SELECT FOUND_ROWS() into total_row_count;
open kursor;
FETCH kursor into dummy;
SET i = 1;
ponavljanje: LOOP
IF i > total_row_count THEN
CLOSE kursor;
LEAVE ponavljanje;
END IF;
FETCH kursor INTO trenutna;
SET zbrojeno = 0;
SET zbrojeno = (SELECT COUNT(*) FROM steamspy_tag_data where trenutna <> 0);
INSERT INTO tagovi(kategorija,broj_igra)
VALUES (
(trenutna),(zbrojeno)
);
SET i = i + 1;
end LOOP;
END
New table tagovi has 3 columns (ID auto_increment, kategorija Varchar(255), broj_igra INTEGER).
When I execute my stored procedure "zbroji_tagove"() I get SQL ERROR CODE 1292; Truncated incorrect DOUBLE value 'some_tag_name'. So somehow sql treats variable value as value instead of column at line SET zbrojeno = (SELECT COUNT() FROM steamspy_tag_data where trenutna <> 0*);
Is there a way for me to accomplish what I want inside MySQL environment?
You can't use variables like that, you need a prepared statement
See
#sql = CONCAT("SELECT COUNT(*) INTO zbrojeno FROM steamspy_tag_data where ",trenutna," <> 0);";
PREPARE stmt1 FROM #sql;
EXECUTE stmt1;
DEALLOCATE PREPARE stmt1;
Related
I have a table that lists tables that I want to get counts off of:
|dq_tbl_id|dq_tbl_tbl_name |dq_tbl_use_batch_stamp|
|---------|--------------------------|----------------------|
|1 |dev_credly_badges |1 |
|... |... |... |
|18 |tbl18 |[NULL] |
I can't figure out why the procedure exits after one iteration:
CREATE DEFINER=`channel`#`%` PROCEDURE `dq_job_dev_count`()
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE proc_dq_tbl_id SMALLINT;
DECLARE tbl_count INT DEFAULT 0;
DECLARE tbl_name VARCHAR(35);
DECLARE dq_tbl_use_batch_stamp BOOL DEFAULT FALSE;
DECLARE dq_tbl_ids
CURSOR FOR
SELECT dq_tbl_id FROM ref_dq_tbl_count;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN dq_tbl_ids;
WHILE done = 0 DO
FETCH NEXT FROM dq_tbl_ids INTO proc_dq_tbl_id;
IF done = 0 THEN
SELECT dq_tbl_tbl_name, dq_tbl_use_batch_stamp INTO #tbl_name, #dq_tbl_use_batch_stamp FROM ref_dq_tbl_count WHERE dq_tbl_id = #proc_dq_tbl_id;
IF #dq_tbl_use_batch_stamp = 1 THEN
SET #sql_stmt = CONCAT('SELECT COUNT(*) INTO #tbl_count FROM ', #tbl_name, ' WHERE DATE(batch_stamp) = CURDATE()');
ELSE
SET #sql_stmt = CONCAT('SELECT COUNT(*) INTO #tbl_count FROM ', #tbl_name);
END IF;
PREPARE stmt FROM #sql_stmt;
EXECUTE stmt;
INSERT INTO prod_dq_tbl_load_counts (tbl_name, row_count) VALUES (#tbl_name, #tbl_count);
END IF;
END WHILE;
CLOSE dq_tbl_ids;
END
You are fetching the cursor result into a local variable:
FETCH NEXT FROM dq_tbl_ids INTO proc_dq_tbl_id;
Subsequently you use a user-defined variable #proc_dq_tbl_id under the mistaken assumption that it contains the value you fetched.
In MySQL stored procedures, a variable with the # sigil is a user-defined variable. It is literally a different variable than the local variable you created with DECLARE.
You can fetch the cursor into a user-defined variable (with the # sigil) or you can fetch the cursor into a local variable. But then you must use the same variable in subsequent expressions.
Since #proc_dq_tbl_id is likely to be NULL, the SELECT statement you use it in will never match any rows. Your cursor is probably looping plenty, but the SELECT statement in each loop iteration is finding no matches.
This treatment of variables in MySQL is different than other brands of SQL database (e.g. Microsoft SQL Server). It is sometimes confusing to developers who are accustomed to using other brands.
I have two (2) databases of dissimilar Schematics,
db1 migrated from MSSQL to MYSQL
and
db2 created from Laravel Migration.
Here's the challenge:
The tables of db1 do not have id columns (Primary Key) like is easily found on db2 tables. So I kept getting the warning message:
Current selection does not contain a unique column. Grid edit, checkbox, Edit, Copy and Delete features are not available.
So I had to inject the id columns on the tables in the db1
I need to extract fields [level_name, class_name] from stdlist in db1,
Create levels (id,level_name,X,Y) on db2
classes (id,class_name,level_id) on db2
To throw more light: The level_id should come from the already created levels table
I have already succeeded in extracting the first instance using the following snippet:
First Query to Create Levels
INSERT INTO db2.levels(level_name,X,Y)
SELECT class_name as level_name,1 as X,ClassAdmitted as Y
FROM db1.stdlist
GROUP BY ClassAdmitted;
This was successful.
Now, I need to use the newly created ids in levels table to fill up level_id column in the classes table.
For that to be possible, must I re-run the above selection schematics? Is there no better way to maybe join the table column from db1.levels to db2.stdlist and extract the required fields for the new insert schematics.
I'll appreciate any help. Thanks in advance.
Try adding a column for Processed and then do a while exists loop
INSERT INTO db2.levels(level_name,X,Y)
SELECT class_name as level_name,1 as X,ClassAdmitted as Y, 0 as Processed
FROM db1.stdlist
GROUP BY ClassAdmitted;
WHILE EXISTS(SELECT * FROM db2.levels WHERE Processed = 0)
BEGIN
DECLARE #level_name AS VARCHAR(MAX)
SELECT TOP 1 #level_name=level_name FROM db2.levels WHERE Processed = 0
--YOUR CODE
UPDATE db2.levels SET Processed=1 WHERE level_name=#level_name
END
You may need to dump into a temp table first and then insert into your real table (db2.levels) when you're done processing. Then you wouldn't need the Unnecessary column of processed on the final table.
This is what worked for me eventually:
First, I picked up the levels from the initial database thus:
INSERT INTO db2.levels(`name`,`school_id`,`short_code`)
SELECT name ,school_id,short_code
FROM db1.levels
GROUP BY name
ORDER BY CAST(IF(REPLACE(name,' ','')='','0',REPLACE(name,' ','')) AS UNSIGNED
INTEGER) ASC;
Then I created a PROCEDURE for the classes insertion
CREATE PROCEDURE dowhileClasses()
BEGIN
SET #Level = 1;
SET #Max = SELECT count(`id`) FROM db2.levels;
START TRANSACTION;
WHILE #Level <= #Max DO
BEGIN
DECLARE val1 VARCHAR(255) DEFAULT NULL;
DECLARE val2 VARCHAR(255) DEFAULT NULL;
DECLARE bDone TINYINT DEFAULT 0;
DECLARE curs CURSOR FOR
SELECT trim(`Class1`)
FROM db1.dbo_tblstudent
WHERE CAST(IF(REPLACE(name,' ','')='','0',REPLACE(name,' ','')) AS UNSIGNED INTEGER) =#Level
GROUP BY `Class1`;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET bDone = 1;
OPEN curs;
SET bDone = 0;
REPEAT
FETCH curs INTO val1;
IF bDone = 0 THEN
SET #classname = val1;
SET #levelID = (SELECT id FROM db2.levels WHERE short_code=#Level limit 1);
SET #schoolId = 1;
SET #classId = (SELECT `id` FROM db2.classes where class_name = #classname and level_id= #levelID limit 1);
IF #classId is null and #classname is not null THEN
INSERT INTO db2.classes(class_name,school_id,level_id)
VALUES(#classname,#schoolId,#levelID);
END IF;
END IF;
UNTIL bDone END REPEAT;
CLOSE curs;
END;
SELECT CONCAT('lEVEL: ',#Level,' Done');
SET #Level = #Level + 1;
END WHILE;
END;
//
delimiter ;
CALL dowhileClasses();
With this, I was able to dump The classes profile matching the previously created level_ids.
The whole magic relies on the CURSOR protocol.
For further details here is one of the documentations I used.
I searched a lot of doing a task but found no appropriate solution.
Basically the scenario is. I have a user_comment table in which there are 5 column(id,parent_id,user_comments,is_deleted,modified_datetime). There is a parent child relationship like 1->2,1->3,2->4,2->5,5->7 etc. Now i am sending the id from the front end and i want to update the column is_deleted to 1 and modified_datetime on all the records on
this id as well as the all the children and children's of children.
I am trying to doing this by using a recursive procedure. Below is the code of my procedure
CREATE DEFINER=`root`#`localhost` PROCEDURE `user_comments`(
IN mode varchar(45),
IN comment_id int,
)
BEGIN
DECLARE p_id INT DEFAULT NULL ;
if(mode = 'delete')
then
update user_comment set is_deleted = 1, modified_datetime = now()
where id = comment_id ;
select id from user_comment where parent_id = comment_id into p_id ;
if p_id is not null
then
SET ##GLOBAL.max_sp_recursion_depth = 255;
SET ##session.max_sp_recursion_depth = 255;
call user_comments('delete', p_id);
end if;
end if;
END
By using this procedure it give me an error of more than one row.
If i return the select query without giving it to variable then shows me the the appropriate results on the select query but i have to call this procedure recursively based on getting the ids of the select query.
I need help i have already passed 2 days into this.
I used cursor also. Below is the code of cursor
CREATE DEFINER=`root`#`localhost` PROCEDURE `user_comments`(
IN mode varchar(45),
IN comment_id int,
)
BEGIN
DECLARE p_emp int;
DECLARE noMoreRow INT;
DECLARE cur_emp CURSOR FOR select id from user_comment where parent_id = comment_id ;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET noMoreRow = 0;
if(mode = 'delete')
then
OPEN cur_emp;
LOOPROWS: LOOP
IF noMoreRow = 0 THEN
update user_comment set is_deleted = 1, modified_datetime = now() where id = comment_id
CLOSE cur_emp;
LEAVE LOOPROWS;
END IF;
FETCH cur_emp INTO p_emp;
update user_comment set is_deleted = 1, modified_datetime = now() where id = p_emp ;
SET ##GLOBAL.max_sp_recursion_depth = 255;
SET ##session.max_sp_recursion_depth = 255;
call user_comments('delete', p_emp);
END LOOP;
end if;
END
After using cursor i am getting a thread error.i don't know how can overcome this problem!!!
Mysql's documentation on select ... into varlist clearly says:
The selected values are assigned to the variables. The number of
variables must match the number of columns. The query should return a
single row. If the query returns no rows, a warning with error code
1329 occurs (No data), and the variable values remain unchanged. If
the query returns multiple rows, error 1172 occurs (Result consisted
of more than one row). If it is possible that the statement may
retrieve multiple rows, you can use LIMIT 1 to limit the result set to
a single row.
Since you wrote in the OP that a comment can be parent of many comments, using simple variables cannot be a solution. You should use a CURSOR instead, that can store an entire resultset.
You loop through the records within the cursos as shown in the sample code in the above link and call user_comments() in a recursive way.
UPDATE
If your receive
Error Code: 1436. Thread stack overrun
error, then you can do 2 things:
Increase the thread_stack setting in the config file and restart mysql server.
You can try to simplify your code to use less recursions and therefore less stack space. For example, when you fetch all children into the cursor, then rather calling the user_comments() recursively for each, you can set all direct children's status within the code and call the function recirsively on grand-childrens only (if any). You can also change your data structure and use nested set model to approach hierarchical structures.
Nested set model is more complex to understand, it is less resource intensive to traverse, but more resource intensive to maintain.
I have databases named company_abc, company_xyz, etc. Those company_* databases have all the same structure and they contain users table.
What I need to do is to aggregate all users data from just company_* databases and replicate this view to another server. The view would just be something like
COMPANY NAME | USERNAME
abc | user#email.com
abc | user1#email.com
xyz | user2#email.com
company3 | user3#email.com
Is something like that possible in MySQL?
The databases are created dynamically, as well as the users so I can't create a view with just a static set of databases.
As you say you want to create view with dynamic database names - so the result you want to achieve is not possible in current versions of mysql.
So you have example following options:
Option 1
If you want to get result of all databases users tables you could define a stored procedure that uses prepared statement. This procedure needs parameter db_prefix what in your case is company_%. Basicly this procedure selects all tables named as users from information_schema when database name is like db_prefix parameter value. After that it loops through results and creates query string as union all users tables and executes this query. When creating a query string i also add field called source, so i can identify from what database this result is coming. In my example my databases are all in default collation utf8_unicode_ci.
In this case you can define procedure example "getAllUsers"
-- Dumping structure for procedure company_abc1.getAllUsers
DELIMITER //
CREATE DEFINER=`root`#`localhost` PROCEDURE `getAllUsers`(IN `db_prefix` TEXT)
DETERMINISTIC
COMMENT 'test'
BEGIN
DECLARE qStr TEXT DEFAULT '';
DECLARE cursor_VAL VARCHAR(255) DEFAULT '';
DECLARE done INTEGER DEFAULT 0;
DECLARE cursor_i CURSOR FOR SELECT DISTINCT (table_schema) FROM information_schema.tables WHERE table_name = 'users' AND table_schema LIKE db_prefix COLLATE utf8_unicode_ci;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cursor_i;
read_loop: LOOP
FETCH cursor_i INTO cursor_VAL;
IF done = 1 THEN
LEAVE read_loop;
END IF;
IF qStr != '' THEN
SET qStr = CONCAT(qStr, ' UNION ALL ');
END IF;
SET qStr = CONCAT(qStr, ' SELECT *, \'', cursor_VAL ,'\' as source FROM ', cursor_VAL, '.users');
END LOOP;
CLOSE cursor_i;
SET #qStr = qStr;
PREPARE stmt FROM #qStr;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET #qStr = NULL;
END//
DELIMITER ;
Now you can get your all users result as:
CALL getAllUsers('company_%');
In my example database it results as:
id name source
1 User 1 company_abc1
2 User 2 company_abc1
3 User 3 company_abc1
1 User 1 company_abc2
2 User 2 company_abc2
3 User 3 company_abc2
1 User 1 company_abc3
2 User 2 company_abc3
3 User 3 company_abc3
1 User 1 company_abc4
2 User 2 company_abc4
3 User 3 company_abc4
1 User 1 company_abc5
2 User 2 company_abc5
3 User 3 company_abc5
Option 2
If you really, really need view then you can modify first procedure and instead of executeing select you can create view. Example like this:
-- Dumping structure for procedure company_abc1.createAllUsersView
DELIMITER //
CREATE DEFINER=`root`#`localhost` PROCEDURE `createAllUsersView`(IN `db_prefix` TEXT)
DETERMINISTIC
COMMENT 'test'
BEGIN
DECLARE qStr TEXT DEFAULT '';
DECLARE cursor_VAL VARCHAR(255) DEFAULT '';
DECLARE done INTEGER DEFAULT 0;
DECLARE cursor_i CURSOR FOR SELECT DISTINCT (table_schema) FROM information_schema.tables WHERE table_name = 'users' AND table_schema LIKE db_prefix COLLATE utf8_unicode_ci;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cursor_i;
read_loop: LOOP
FETCH cursor_i INTO cursor_VAL;
IF done = 1 THEN
LEAVE read_loop;
END IF;
IF qStr != '' THEN
SET qStr = CONCAT(qStr, ' UNION ALL ');
END IF;
SET qStr = CONCAT(qStr, ' SELECT *, \'', cursor_VAL ,'\' as source FROM ', cursor_VAL, '.users');
END LOOP;
CLOSE cursor_i;
SET #qStr = CONCAT('CREATE OR REPLACE VIEW allUsersView AS ', qStr);
PREPARE stmt FROM #qStr;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET #qStr = NULL;
END//
DELIMITER ;
In this stored procedure we create/replace view called allUsersView, so basicly every time you will execute this procedure it will updates view.
In my test case it creates view like this:
CREATE OR REPLACE VIEW `allusersview` AS
SELECT *, 'company_abc1' as source FROM company_abc1.users
UNION ALL SELECT *, 'company_abc2' as source FROM company_abc2.users
UNION ALL SELECT *, 'company_abc3' as source FROM company_abc3.users
UNION ALL SELECT *, 'company_abc4' as source FROM company_abc4.users
UNION ALL SELECT *, 'company_abc5' as source FROM company_abc5.users ;
And now you can use view.
SELECT * FROM allusersview
And result is same as in first option.
All tested on:
Mysql 5.6.16
To find the list of database names:
SELECT SCHEMA_NAME
FROM information_schema.`SCHEMATA`
WHERE SCHEMA_NAME LIKE 'company%';
If you can code in something like PHP, the rest is pretty easy -- build a UNION of SELECTs from each database. But, if you must do it just in SQL...
To build the UNION, write a Stored Procedure. It will do the above query in a CURSOR. Inside the loop that walks through the cursor, CONCAT() a constructed SELECT onto a UNION you are building.
When the loop is finished, PREPARE and EXECUTE the constructed UNION. That will deliver something like the output example you had.
But, if you now need to INSERT the results of that into another server, you should leave the confines of the Stored Procedure and use some other language.
OK, OK, if you must stay in SQL, then you need some setup: Create a "Federated" table that connects to the other server. Now, in your SP, concatenate INSERT INTO fed_tbl in front of the UNION. Then the execute should do the entire task.
If you have trouble with the FEDERATED Engine, you may need to switch to FederatedX in MariaDB.
"The details are left as an exercise to the reader."
I already marked this as duplicate of Mysql union from multiple database tables
(SELECT *, 'abc' as COMPANY_NAME from company_abc.users)
union
(SELECT *, 'xyz' as COMPANY_NAME from company_xyz.users)
union
(SELECT *, 'company3' as COMPANY_NAME from company_company3.users)
...
I think that the only method to make this is to write a stored procedure that read all database and table name from information_schema.table, build a string with union select * from company_abc.users union all select * from company_xyz and then execute the command with prepared statement: http://dev.mysql.com/doc/refman/5.0/en/sql-syntax-prepared-statements.html
In MySQL, I am converting a table from a single row per item type (a quantity of items) to a single row per item, so that additional detail can be stored about individual items.
Here is an example source table:
id parent_id qty item_type
-- --------- --- ---------
1 10291 2 widget
2 10292 4 thinger
I want to create a new table with a new column containing info that cannot be applied to more than one item. Thus, the above table would end up as follows:
id parent_id item_type info
-- --------- --------- ----
1 10291 widget [NULL]
2 10291 widget [NULL]
3 10292 thinger [NULL]
4 10292 thinger [NULL]
5 10292 thinger [NULL]
6 10292 thinger [NULL]
Is there a way I can iterate or loop each row of the source table, inserting a number of records equal to the source qty column? I would prefer to do this in sql instead of code to keep all of the conversion steps together (there are many others).
You can do with stored procedure. That will be like below. Below is stored procedure I am using for inserting products into log based on their quantity.
Seem you have to do similar task. You can get how to use database cursor in stored procedure to loop over a result set in MySQL from below example.
DELIMITER $$
DROP PROCEDURE IF EXISTS CursorProc$$
CREATE PROCEDURE CursorProc()
BEGIN
DECLARE no_more_products, quantity_in_stock INT DEFAULT 0;
DECLARE prd_code VARCHAR(255);
DECLARE cur_product CURSOR FOR
SELECT productCode FROM products;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET no_more_products = 1;
/* for loggging information */
CREATE TABLE infologs (
Id int(11) NOT NULL AUTO_INCREMENT,
Msg varchar(255) NOT NULL,
PRIMARY KEY (Id)
);
OPEN cur_product;
FETCH cur_product INTO prd_code;
REPEAT
SELECT quantityInStock INTO quantity_in_stock
FROM products
WHERE productCode = prd_code;
IF quantity_in_stock < 100 THEN
INSERT INTO infologs(msg)
VALUES (prd_code);
END IF;
FETCH cur_product INTO prd_code;
UNTIL no_more_products = 1
END REPEAT;
CLOSE cur_product;
SELECT * FROM infologs;
DROP TABLE infologs;
END$$
DELIMITER;
Seems your task is 90% same as above procedure. Just do needful changes. It will work.
I think you can create stored procedure, declare a cursor that reads source table and for each row inserts qty rows into destination table.
Based on other answers which provided some insight, I was able to find additional information (by Kevin Bedell) to create a stored procedure and use a cursor in a loop. I have simplified my solution so that it matches the example in my question:
DROP PROCEDURE IF EXISTS proc_item_import;
DELIMITER $$
CREATE PROCEDURE proc_item_import()
BEGIN
# Declare variables to read records from the cursor
DECLARE parent_id_val INT(10) UNSIGNED;
DECLARE item_type_val INT(10) UNSIGNED;
DECLARE quantity_val INT(3);
# Declare variables for cursor and loop control
DECLARE no_more_rows BOOLEAN;
DECLARE item_qty INT DEFAULT 0;
# Declare the cursor
DECLARE item_cur CURSOR FOR
SELECT
i.parent_id, i.qty, i.item_type
FROM items i;
# Declare handlers for exceptions
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET no_more_rows = TRUE;
# Open the cursor and loop through results
OPEN item_cur;
input_loop: LOOP
FETCH item_cur
INTO parent_id_val, item_type_val, quantity_val;
# Break out of the loop if there were no records or all have been processed
IF no_more_rows THEN
CLOSE item_cur;
LEAVE input_loop;
END IF;
SET item_qty = 0;
qty_loop: LOOP
INSERT INTO items_new
(parent_id, item_type)
SELECT
parent_id_val, item_type_val;
SET item_qty = item_qty + 1;
IF item_qty >= quantity_val THEN
LEAVE qty_loop;
END IF;
END LOOP qty_loop;
END LOOP input_loop;
END$$
DELIMITER ;
Before asking this question, I had not used a stored procedures, cursors, or loops. That said, I have read and encountered them frequently on SE and elsewhere, and this was a good opportunity to learn
It may be worth noting that the example on Kevin's page (linked above) does not use END%% (just END) which caused some headache in trying to get the script to work. When creating a procedure, it is necessary to change the delimiter temporarily so that semicolons terminate statements inside the procedure, but not the creation process of the procedure itself.
That is just an example of code that I have here, it is not adapted to your needs, but it does exactly what you need, and it is simple than a procedure, or temporary table.
SELECT event, id, order_ref, storeitem_barcode_create(8), NOW()
FROM (
SELECT mss.id, mss.event, mss.order_ref, mss.quantity, mss.product_id,
#rowID := IF(#lastProductID = mss.product_id AND #lastID = mss.id, #rowID + 1, 0) AS rowID,
#lastProductID := mss.product_id,
#lastID := mss.id
FROM module_barcode_generator mbg,
(SELECT #rowID := 0, #lastProductID := 0, #lastID := 0) t
INNER JOIN module_events_store_sold mss ON mss.order_ref = "L18T2P"
) tbl
WHERE rowId < quantity;
Typo in JYelton's solution for his/her own question:
FETCH item_cur
INTO parent_id_val, item_type_val, quantity_val;
Should be:
FETCH item_cur
INTO parent_id_val, quantity_val, item_type_val;
Otherwise very good.