I've tried a couple of approaches to update a column in a mySQL database table from another table but am not having any luck.
I read somewhere that version 3.5.2 does not support multi-table updates and I need a code-based solution - is that correct?
If not can anybody point me in the right direction using sql?
UPDATE products SET products_ordered = (
SELECT SUM(products_quantity)
FROM orders_products
WHERE products_id = products.products_id
);
or:
Create temporary table my_temp_table
as
SELECT products_id, SUM(products_quantity) as total
FROM orders_products
GROUP BY products_id
UPDATE products, my_temp_table
SET products.products_ordered = my_temp_table.total
WHERE products.products_id = my_temp_table.products_id
When I used to use MySQL that did not support either subqueries or multi-table updates, I used a trick to do what you're describing. Run a query whose results are themselves SQL statements, and then save the output and run that as an SQL script.
SELECT CONCAT(
'UPDATE products SET products_ordered = ',
SUM(products_quantity),
' WHERE product_id = ', products_id, ';') AS sql_statement
FROM orders_products
GROUP BY products_id;
By the way, there is no such version MySQL 3.5.x as far as I know. I think you may have reported that wrong. Or else you're using another product such as mSQL.
Edit: I forgot to add a semicolon into the SQL statement generated by the query above.
MySQL <= 4.0.4 不支持多表更新 我强烈建议将您的服务器更新到 MySQL 5.0.xx
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