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- [轉貼]如何更新資料表欄位透過其他資料表（UPDATE FROM TABLE）
用其它的 Table 來更新資料(Update From Table)
UPDATE table1
SET table1.col = table2.col1
FROM table2
WHERE table2.oldCol = table1.col
原文出處：[MSSQL] 用其它的 Table 來更新資料(Update From Table) @ 菲力貓的程式設計 :: 痞客邦 PIXNET ::
UPDATE from SELECT using SQL Server
In SQL Server you can insert into a table using a select statement:
INSERT INTO table(col,col2,col3)
SELECT col,col2,col3 FROM other_table WHERE sql = 'cool'
How can I update via a select as well in a similar manner? I have a temporary table that has the values, and I want to update another table using those values.
Something like this:
UPDATE Table SET col1,col2
SELECT col1,col2 FROM other_table WHERE sql = 'cool'
WHERE Table.id = other_table.id
UPDATE
Table
SET
Table.col1 = other_table.col1,
Table.col2 = other_table.col2
FROM
Table
INNER JOIN
other_table
ON
Table.id = other_table.id
In SQL Server 2008 (or better), use MERGE
MERGE INTO "Table" T
USING other_table S
ON T.id = S.id
AND S.sql = 'cool'
WHEN MATCHED THEN
UPDATE
SET col1 = S.col1,
col2 = S.col2;
Alternatively:
MERGE INTO "Table" T
USING (
SELECT id, col1, col2
FROM other_table
WHERE sql = 'cool'
) S
ON T.id = S.id
WHEN MATCHED THEN
UPDATE
SET col1 = S.col1,
col2 = S.col2;
I'd modify Robin's excellent answer to the following:
UPDATE
Table
SET
Table.col1 = other_table.col1,
Table.col2 = other_table.col2
FROM
Table
INNER JOIN
other_table
ON
Table.id = other_table.id
WHERE
Table.col1 != other_table.col1 or
Table.col2 != other_table.col2 or
(other_table.col1 is not null and table.col1 is null) or
(other_table.col2 is not null and table.col2 is null)
Without a WHERE clause, you'll affect even rows that don't need to be affected, which could (possibly) cause index recalculation or fire triggers that really shouldn't have been fired.
share|improve this answer
Another possibility not mentioned yet is to just chuck the SELECT statement itself into a CTE then Update the CTE.
;WITH CTE
AS (SELECT T1.Col1,
T2.Col1 AS _Col1,
T1.Col2,
T2.Col2 AS _Col2
FROM T1
JOIN T2
ON T1.id = T2.id
/*Where clause added to exclude rows that are the same in both tables
Handles NULL values correctly*/
WHERE EXISTS(SELECT T1.Col1,
T1.Col2
EXCEPT
SELECT T2.Col1,
T2.Col2))
UPDATE CTE
SET Col1 = _Col1,
Col2 = _Col2
This has the benefit that it is easy to run the SELECT statement on its own first to sanity check the results but it does requires you to alias the columns as above if they are named the same in source and target tables.
This also has the same limitation as the proprietary UPDATE ... FROM syntax shown in four of the other answers. If the source table is on the many side of a one to many join then it is undeterministic which of the possible matching joined records will be used in the Update (An issue that MERGE avoids by raising an error if there is an attempt to update the same row more than once).
One way
UPDATE t SET t.col1 = o.col1,
t.col2 = o.col2
FROM other_table o
join t on t.id = o.id
WHERE o.sql = 'cool'
UPDATE Table SET Col1=i.Col1 ,
Col2=i.Col2 FROM (SELECT Col1,Col2 FROM other_table)i
where i.ID=Table.ID
For the record (and others searching like I was), you can do it in MySQL like this:
UPDATE first_table, second_table
SET first_table.color = second_table.color
WHERE first_table.id = second_table.foreign_id
Using alias:
UPDATE t
SET t.col1 = o.col1
FROM table1 AS t
INNER JOIN
table2 AS o
ON t.id = o.id
This may be a niche reason to perform an update (for example, mainly used in a procedure), or may be obvious to others, but it should also be stated that you can perform an update-select statement without using join (in case the tables you're updating between have no common field).
update
Table
set
Table.example = a.value
from
TableExample a
where
Table.field = *key value* -- finds the row in Table
AND a.field = *key value* -- finds the row in TableExample a
The sample way to do it is:
UPDATE
table_to_update,
table_info
SET
table_to_update.col1 = table_info.col1,
table_to_update.col2 = table_info.col2
WHERE
table_to_update.ID = table_info.ID
I add this only so you can see a quick way to write it so that you can check what will be updated before doing the update.
UPDATE Table
SET Table.col1 = other_table.col1,
Table.col2 = other_table.col2
--select Table.col1, other_table.col,Table.col2,other_table.col2, *
FROM Table
INNER JOIN other_table
ON Table.id = other_table.id
here is another useful syntax:
UPDATE suppliers
SET supplier_name = (SELECT customers.name
FROM customers
WHERE customers.customer_id = suppliers.supplier_id)
WHERE EXISTS (SELECT customers.name
FROM customers
WHERE customers.customer_id = suppliers.supplier_id);
it checks if it is null or not by using "WHERE EXIST"
原文出處：UPDATE from SELECT using SQL Server - Stack Overflow
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[轉貼]如何更新資料表欄位透過其他資料表（UPDATE FROM TABLE） (冷日