如何将 SELECT EXISTS() 查询链接在一起？

发布于 2024-10-27 08:54:13 字数 379 浏览 4 评论 0原文

我有一个简单的查询，

SELECT EXISTS(SELECT a FROM A WHERE a = 'lorem ipsum');

如果 A 中存在包含“lorem ipsum”的行，它将返回 0 或 1

我想将此行为链接在一起。所以我会得到多行，如果该值存在，每行都有 0 或 1。

我该怎么做呢？

更新：

可以这样做，但随后我会得到每个结果的一列。

SELECT EXISTS(SELECT a FROM A WHERE a = 'lorem ipsum'), EXISTS(SELECT a FROM A WHERE a = 'dolor sit');

原文

I have this simple query

SELECT EXISTS(SELECT a FROM A WHERE a = 'lorem ipsum');

That will return a 0 or 1 if there exists a row in A that contains 'lorem ipsum'

I would like to chain this behavior together. So I would get multiple rows, each with a 0 or 1 if that value exists.

How would I go about doing this?

Update:

It's possible to do it like this but then I get a column for each result.

SELECT EXISTS(SELECT a FROM A WHERE a = 'lorem ipsum'), EXISTS(SELECT a FROM A WHERE a = 'dolor sit');

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御弟哥哥 2024-11-03 08:54:13

SELECT EXISTS(SELECT a FROM A WHERE a = 'lorem ipsum')
UNION ALL
SELECT EXISTS(SELECT a FROM A WHERE a = 'dolor sit');

或者

SELECT EXISTS(SELECT a FROM A WHERE A.a = T.a)
FROM (SELECT 'lorem ipsum' AS a 
      UNION ALL 
      SELECT 'dolor sit') T

SELECT EXISTS(SELECT a FROM A WHERE a = 'lorem ipsum')
UNION ALL
SELECT EXISTS(SELECT a FROM A WHERE a = 'dolor sit');

SELECT EXISTS(SELECT a FROM A WHERE A.a = T.a)
FROM (SELECT 'lorem ipsum' AS a 
      UNION ALL 
      SELECT 'dolor sit') T

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深海蓝天 2024-11-03 08:54:13

手头没有 SQL 服务器，但请尝试以下操作：

SELECT CASE WHEN EXISTS (...) THEN 1 ELSE 0 END
UNION ALL
SELECT CASE WHEN EXISTS (...) THEN 1 ELSE 0 END

Don't have an SQL server handy, but try this:

SELECT CASE WHEN EXISTS (...) THEN 1 ELSE 0 END
UNION ALL
SELECT CASE WHEN EXISTS (...) THEN 1 ELSE 0 END

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疾风者 2024-11-03 08:54:13

我会用这样的东西。

    SELECT
        CASE
            WHEN a = 'lorem ipsum' THEN 1
            WHEN a = 'dolor sit' THEN 1
            ELSE 0
        END AS something
    FROM A;

I would use something like this.

    SELECT
        CASE
            WHEN a = 'lorem ipsum' THEN 1
            WHEN a = 'dolor sit' THEN 1
            ELSE 0
        END AS something
    FROM A;

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