Question

我正在尝试执行以下查询

INSERT INTO MyTable(Column1, Column2)
SELECT Column1Value, 'Temp'   -- This will return multiple values which are to be inserted.
FROM Table2 t2
    INNER JOIN Table3 t3 ON t2.Column1 = t3.Column1
    ...
    Few more joins
    ...
WHERE t2.Column3 = 0

正如您在插入查询数据中看到的那样，行来自另一个查询。（这就是为什么我不能在这里使用WHERE != something）我能够运行此查询，但问题是当几个记录已经存在时，这将抛出异常。所以我需要确保只对那些不存在的记录执行此查询。

有人可以帮忙吗？

谢谢＆amp;的问候，

内甚

Answer 1

如何添加条件如下：

where not exists (select 1
                  from mytable t
                  where t.column1 = column1value and t.column2 = 'temp'
                 )

这假设两列一起构成唯一或主键。

您的选择也可能返回重复值，这会导致问题。因此，您也可以将select更改为select distinct：

INSERT INTO MyTable(Column1, Column2)
    SELECT DISTINCT Column1Value, 'Temp'
    FROM Table2 t2
        INNER JOIN Table3 t3 ON t2.Column1 = t3.Column1
        ...
        Few more joins
        ...
    WHERE t2.Column3 = 0 AND
          NOT EXISTS (select 1
                      from mytable t
                      where t.column1 = column1value and t.column2 = 'temp'
                     );

Answer 2

你可以这样做：

INSERT INTO MyTable(Column1, Column2)
SELECT Column1Value, 'Temp'
FROM Table2 t2
    INNER JOIN Table3 t3 ON t2.Column1 = t3.Column1
    ...
    Few more joins
    ...
WHERE t2.Column3 = 0
AND 
NOT EXISTS (SELECT Column1 FROM MyTable MT WHERE MT.col1 = t2.col1);

数据集来自select查询时不存在的SQL插入

2 个答案: