在一个查询下将SQL查询结果与另一个查询语句相结合？ （复杂）

Question

我目前想要将两个SQL查询合并为一个。这有点类似于SQL: Taking the result of of query and using it another - combine。假设有两个查询：

  

SQL声明

1.) SELECT * 
    FROM (SELECT B.example1  
          FROM EXAMPLE1A A  
          INNER JOIN EXAMPLE1B B ON A.ID = B.ID  
          WHERE A.ABC ='ABC' 
          ORDER BY A.ORDER_BY ) as colstate

2.) SELECT colstate 
    FROM EXAMPLE_TABLE 
    WHERE EFG LIKE '%' 
      AND BGTHAN >= '1' 
      AND SMTHAN <= '100' 
    ORDER BY ORDER_BY ASC

我想在查询1中使用结果作为查询2中的colstate（列语句）。）。但是：

  

我尝试过的是：

SELECT (SELECT B.example1  
        FROM EXAMPLE1A A  
        INNER JOIN EXAMPLE1B B 
           ON A.ID = B.ID  
        WHERE A.ABC ='ABC' 
        ORDER BY A.ORDER_BY ) 
FROM EXAMPLE_TABLE 
WHERE EFG LIKE '%' 
  AND BGTHAN >= '1' 
  AND SMTHAN <= '100' 
ORDER BY ORDER_BY ASC

结果是错误：标量子查询只允许返回单行，我应该如何将“=”替换为“IN”？或者我的陈述完全错了？

Answer 1

错误表明您用作列语句的查询最多只能返回一行。

应该看起来像这样：

SELECT (SELECT B.example1  
        FROM EXAMPLE1A A  
        INNER JOIN EXAMPLE1B B 
           ON A.ID = B.ID  
        WHERE A.ABC ='ABC' 
          AND A.SOME_COLUMN = E.SOMECOLUMN // retrieve only relevant data for this row
        ORDER BY A.ORDER_BY ) 
FROM EXAMPLE_TABLE E 
WHERE EFG LIKE '%' 
  AND BGTHAN >= '1' 
  AND SMTHAN <= '100' 
ORDER BY ORDER_BY ASC

Answer 2

“将两个查询合并为一个” - 这不是一个好的规范。尝试找出你想要作为FLAT二维表得到的确切内容，将嵌套的SELECT视为嵌套循环，其中内部的只能为父行设置单个值。像这样：

[Outer loop - parent row]
    [Inner loop - children rows]
        // all you can do here is change a single parent's field to anything
        // like constant/sum/avg/topmost/ugly-subquery-returning-a-single-result
    [/Inner loop]
[/Outer loop]