Question

我正在尝试编写查询来查找另一个表中没有匹配记录的记录。

例如，我有两个表，其结构如下所示：

Table1
    State | Product | Distributor | other fields
    CA    | P1      |  A          | xxxx
    OR    | P1      |  A          | xxxx
    OR    | P1      |  B          | xxxx
    OR    | P1      |  X          | xxxx
    WA    | P1      |  X          | xxxx
    VA    | P2      |  A          | xxxx

Table2
    State | Product | Version | other fields
    CA    | P1      |  1.0    | xxxx
    OR    | P1      |  1.5    | xxxx
    WA    | P1      |  1.0    | xxxx
    VA    | P2      |  1.2    | xxxx

（州/产品/经销商共同构成表1的关键。州/产品是表2的关键）

我想找到所有未使用经销商X的州/产品/版本组合。（因此本例中的结果是CA-P1-1.0和VA-P2-1.2。）

有关查询的任何建议吗？

Answer 1

SELECT
    *
FROM
    Table2 T2
WHERE
    NOT EXISTS (SELECT *
        FROM
           Table1 T1
        WHERE
           T1.State = T2.State AND
           T1.Product = T2.Product AND
           T1.Distributor = 'X')

这应符合ANSI标准。

Answer 2

在T-SQL中：

SELECT DISTINCT Table2.State, Table2.Product, Table2.Version
FROM Table2 
  LEFT JOIN Table1 ON Table1.State = Table2.State AND Table1.Product = Table2.Product AND Table1.Distributor = 'X'
WHERE Table1.Distributor IS NULL

不需要子查询。

编辑：正如评论所示，DISTINCT不是必需的。谢谢！

Answer 3

从table1中选择*，其中state not in（select table from table1 where distributor ='X'）

可能不是最聪明但也应该有效。

Answer 4

SELECT DISTINCT t2.State, t2.Product, t2.Version
FROM table2 t2
JOIN table1 t1 ON t1.State = t2.State AND t1.Product = t2.Product
                AND t1.Distributor <> 'X'

Answer 5

在Oracle中：

SELECT t2.State, t2.Product, t2.Version
FROM Table2 t2, Table t1
WHERE t1.State(+) = t2.State
  AND t1.Product(+) = t2.Product
  AND t1.Distributor(+) = :distributor
  AND t1.State IS NULL

使用SQL查找不匹配的记录

5 个答案: