在SQL Server中,可以使用insert将行插入到表中。。SELECT语句:

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

是否也可以使用SELECT更新表?我有一个包含这些值的临时表,并希望使用这些值更新另一个表。也许是这样的:

UPDATE Table SET col1, col2
SELECT col1, col2 
FROM other_table 
WHERE sql = 'cool'
WHERE Table.id = other_table.id

当前回答

如果使用MySQL而不是SQL Server,语法为:

UPDATE Table1
INNER JOIN Table2
ON Table1.id = Table2.id
SET Table1.col1 = Table2.col1,
    Table1.col2 = Table2.col2

其他回答

UPDATE TQ
SET TQ.IsProcessed = 1, TQ.TextName = 'bla bla bla'
FROM TableQueue TQ
INNER JOIN TableComment TC ON TC.ID = TQ.TCID
WHERE TQ.IsProcessed = 0

要确保正在更新所需内容,请先选择

SELECT TQ.IsProcessed, 1 AS NewValue1, TQ.TextName, 'bla bla bla' AS NewValue2
FROM TableQueue TQ
INNER JOIN TableComment TC ON TC.ID = TQ.TCID
WHERE TQ.IsProcessed = 0

我添加这个只是为了让你可以看到一个快速的方法来编写它,这样你就可以在更新之前检查将要更新的内容。

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 

我以前使用过INSERT SELECT。对于那些想使用新东西的人来说,这里有一个类似的解决方案,但它要短得多:

UPDATE table1                                          // Table that's going to be updated.
LEFT JOIN                                              // Type of join.
    table2 AS tb2                                      // Second table and rename for easy.
ON
    tb2.filedToMatchTables = table1.fieldToMatchTables // Fields to connect both tables.
SET
    fieldFromTable1 = tb2.fieldFromTable2;             // Field to be updated on table1.

    field1FromTable1 = tb2.field1FromTable2,           // This is in the case you need to
    field1FromTable1 = tb2.field1FromTable2,           // update more than one field.
    field1FromTable1 = tb2.field1FromTable2;           // Remember to put ; at the end.

甚至还有一种更短的方法,可能会让你感到惊讶:

示例数据集:

CREATE TABLE #SOURCE ([ID] INT, [Desc] VARCHAR(10));
CREATE TABLE #DEST   ([ID] INT, [Desc] VARCHAR(10));

INSERT INTO #SOURCE VALUES(1,'Desc_1'), (2, 'Desc_2'), (3, 'Desc_3');
INSERT INTO #DEST   VALUES(1,'Desc_4'), (2, 'Desc_5'), (3, 'Desc_6');

代码:

UPDATE #DEST
SET #DEST.[Desc] = #SOURCE.[Desc]
FROM #SOURCE
WHERE #DEST.[ID] = #SOURCE.[ID];

另一种尚未提及的可能性是将SELECT语句本身放入CTE,然后更新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;

这样做的好处是,首先很容易单独运行SELECT语句来检查结果的完整性,但如果源表和目标表中的列名称相同,则需要如上所述对列进行别名。

这也具有与专有UPDATE相同的限制。。。其他四个答案中显示了FROM语法。如果源表位于一对多连接的多方,则无法确定更新中将使用哪些可能匹配的连接记录(如果多次尝试更新同一行,MERGE会通过引发错误来避免此问题)。