使用 SQL 查找不匹配的记录 [英] Finding unmatched records with SQL

问题描述

我正在尝试编写查询以查找在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:

<前>表格1状态 |产品 |经销商 |其他领域CA |P1 |一个 |xxx或 |P1 |一个 |xxx或 |P1 |乙 |xxx或 |P1 |X |xxxWA |P1 |X |xxx弗吉尼亚州 |P2 |一个 |xxx表2状态 |产品 |版本 |其他领域CA |P1 |1.0 |xxx或 |P1 |1.5 |xxxWA |P1 |1.0 |xxx弗吉尼亚州 |P2 |1.2 |xxx

(State/Product/Distributor 共同构成 Table1 的 key.State/Product 是 Table2 的 key)

我想找到所有未使用分销商 X 的状态/产品/版本组合.(因此本示例中的结果是 CA-P1-1.0 和 VA-P2-1.2.)

对查询有什么建议吗?

解决方案

SELECT*从表2 T2在哪里不存在(选择 *从表1 T1在哪里T1.State = T2.State ANDT1.Product = T2.Product ANDT1.Distributor = 'X')

这应该符合 ANSI.

I'm trying write a query to find records which don't have a matching record in another table.

For example, I have a two tables whose structures looks something like this:

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

(State/Product/Distributor together form the key for Table1. State/Product is the key for Table2)

I want to find all the State/Product/Version combinations which are Not using distributor X. (So the result in this example is CA-P1-1.0, and VA-P2-1.2.)

Any suggestions on a query to do this?

解决方案

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')

This should be ANSI compliant.

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