SQL update query using joins
I have to update a field with a value which is returned by a join of 3 tables.
Example:
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
I want to update the mf_item_number field values of table item_master with some other value which is joined in the above condition.
How can I do this in MS SQL Server?
UPDATE im
SET mf_item_number = gm.SKU --etc
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
To make it clear... The UPDATE clause can refer to an table alias specified in the FROM clause. So im in this case is valid
Generic example
UPDATE A
SET foo = B.bar
FROM TableA A
JOIN TableB B
ON A.col1 = B.colx
WHERE ...
One of the easiest way is to use a common table expression (since you're already on SQL 2005):
with cte as (
select
im.itemid
,im.sku as iSku
,gm.SKU as GSKU
,mm.ManufacturerId as ManuId
,mm.ManufacturerName
,im.mf_item_number
,mm.ManufacturerID
, <your other field>
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)
update cte set mf_item_number = <your other field>
The query execution engine will figure out on its own how to update the record.
将它适配到MySQL - 在UPDATE没有FROM子句，但是这起作用：
UPDATE
item_master im
JOIN
group_master gm ON im.sku=gm.sku
JOIN
Manufacturer_Master mm ON gm.ManufacturerID=mm.ManufacturerID
SET
im.mf_item_number = gm.SKU --etc
WHERE
im.mf_item_number like 'STA%'
AND
gm.manufacturerID=34
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