SQL UPDATE query using JOIN
Suppose you need to update a field in a table based on values retrieved from a join of multiple tables. For example, you might have an item_master (im) table that contains a mf_item_number field that needs to be updated based on data from group_master (gm) and Manufacturer_Master (mm).
SELECT im.itemid, im.sku AS iSku, gm.SKU AS GSKU, mm.ManufacturerId AS ManuId, mm.ManufacturerName, im.mf_item_number, mm.ManufacturerID FROM item_master im, group_master gm, Manufacturer_Master mm WHERE im.mf_item_number LIKE 'STA%' AND im.sku = gm.sku AND gm.ManufacturerID = mm.ManufacturerID AND gm.manufacturerID = 34;
To update the mf_item_number field in item_master, you can use the following SQL statement:
UPDATE im SET mf_item_number = gm.SKU FROM item_master im JOIN group_master gm ON im.sku = gm.sku JOIN Manufacturer_Master mm ON gm.ManufacturerID = mm.ManufacturerID WHERE im.mf_item_number LIKE 'STA%' AND gm.manufacturerID = 34;
This query updates the mf_item_number field in item_master based on the SKU value in group_master, which itself is filtered by a condition involving Manufacturer_Master.
Here is an example of a generic update query using joins:
UPDATE A SET foo = B.bar FROM TableA A JOIN TableB B ON A.col1 = B.colx WHERE ...;
In this example, the UPDATE clause references table alias A in the FROM clause to update field foo based on the B.bar value retrieved from the join between TableA and TableB.
The above is the detailed content of How to Update a Table Field Using SQL Joins?. For more information, please follow other related articles on the PHP Chinese website!

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