Question

我必须在Postgres中执行一个函数，它需要从同一个表中返回两个不同查询的结果，并在同一个表字段（主键）上使用where子句。

具有相同索引号的那些（又名inIndex，outIndex）与一个输入相关，第二个是输出。

示例：

SELECT 
       '9' as inIndex, 
       name as inFieldName 
    from FIELDS 
    where field_id = 1000000005

UNION

SELECT 
       '10' as inIndex, 
       name as inFieldName 
    from FIELDS 
    where field_id = 1000000007;

SELECT  
       '9' as outIndex, 
       name as outFieldName 
    from FIELDS 
    where field_id = 1000000004

UNION 

SELECT  
       '10' as outIndex, 
       name as outFieldName 
    from FIELDS 
    where field_id = 1000000006;

有没有办法将两个查询混合成一个？

如果没有，我如何将两个查询结果都返回到pl / pgsql函数中的一个结果集中？

到目前为止，我已经提出了两个循环，在一个包含3列的自定义类型中添加结果（index，inFiled，outField）。这个程序有更好的方法吗？

Answer 1

这样的事情：

SELECT
    '9' AS FieldIndex,
    InFields.name AS InFieldName,
    OutFields.name AS OutFieldName
FROM
    FIELDS AS InFields,
    FIELDS AS OutFields
WHERE
    InFields.field_id = 1000000005
AND OutFields.field_id = 1000000004

UNION

SELECT
    '10' AS FieldIndex,
    InFields.name AS InFieldName,
    OutFields.name AS OutFieldName
FROM
    FIELDS AS InFields,
    FIELDS AS OutFields
WHERE
    InFields.field_id = 1000000007
AND OutFields.field_id = 1000000006

显然你可能需要调整一下......

如何在where子句中将两个不同的sql查询组合成一个主键

1 个答案: