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How do I UPDATE from a SELECT in SQL Server?


Question

In SQL Server, it is possible to insert rows into a table with an INSERT.. SELECT statement:

INSERT INTO Table (col1, col2, col3)
SELECT col1, col2, col3 
FROM other_table 
WHERE sql = 'cool'

Is it also possible to update a table with SELECT? I have a temporary table containing the values and would like to update another table using those values. Perhaps something like this:

UPDATE Table SET col1, col2
SELECT col1, col2 
FROM other_table 
WHERE sql = 'cool'
WHERE Table.id = other_table.id
2020/08/12
1
3771
8/12/2020 10:35:08 PM

Accepted Answer

UPDATE
    Table_A
SET
    Table_A.col1 = Table_B.col1,
    Table_A.col2 = Table_B.col2
FROM
    Some_Table AS Table_A
    INNER JOIN Other_Table AS Table_B
        ON Table_A.id = Table_B.id
WHERE
    Table_A.col3 = 'cool'
2016/04/30
5463
4/30/2016 1:26:35 AM

In SQL Server 2008 (or better), use MERGE

MERGE INTO YourTable T
   USING other_table S 
      ON T.id = S.id
         AND S.tsql = 'cool'
WHEN MATCHED THEN
   UPDATE 
      SET col1 = S.col1, 
          col2 = S.col2;

Alternatively:

MERGE INTO YourTable T
   USING (
          SELECT id, col1, col2 
            FROM other_table 
           WHERE tsql = 'cool'
         ) S
      ON T.id = S.id
WHEN MATCHED THEN
   UPDATE 
      SET col1 = S.col1, 
          col2 = S.col2;
2014/04/03

UPDATE YourTable 
SET Col1 = OtherTable.Col1, 
    Col2 = OtherTable.Col2 
FROM (
    SELECT ID, Col1, Col2 
    FROM other_table) AS OtherTable
WHERE 
    OtherTable.ID = YourTable.ID
2020/01/01

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.

2018/05/19

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'
2015/05/20

Another possibility not mentioned yet is to just chuck the SELECT statement itself into a CTE and 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).

2018/05/19

Source: https://stackoverflow.com/questions/2334712
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