如果两个不同表中的两个相同列具有值，如何返回true？SQL

回到这里，再问你们一个问题

我们有两个数据透视表，表A和表B。两个表都有相同的列

我试图编写一个查询，该查询将遍历每一行，仅当具有相同ID的记录在“value”字段中有值时才返回true。 因此，例如，对于记录ID3，表_A具有“sdnbfsj”值，而对于相同的记录ID，表_B具有“value”字段下的值

查询应该能够验证两个表中的同一单元格是否有值，如果有，则返回true。如果表总共只有三条记录，则返回true，但请注意，记录ID 5在表_a中有一个值，而记录ID 5在表_B中为NULL。因此查询应返回false

这就是我到目前为止所做的：

SELECT source_column from 
(
select source_column from Table_A WHERE Value_Inserted=1
EXCEPT
select source_column from Table_B WHERE Value_Inserted=1
)X
WHERE source_column  IN 
(
'Col_1'
,'COl_2'
,'Col_3'
,'Col_4'
)

---

您应该能够这样做，首先将

id

上的两个表连接起来，然后根据您的情况进行计数。然后。。。返回“真”或“假”

语法可能因您使用的RDBMS而异

我想你想要：

select min(case when a.value is not null and a.value is null then 0
                when a.value is null a and a.value is not null then 0
                else 1
           end) as flag
from a join
     b
     on a.class = b.class and a.source_col = b.source_col;

这将1视为真，0视为假。

取决于您使用的DBMS

对于Oracle使用

nvl2

功能：

select nvl2(a.value, 1, 0) * nvl2(b.value, 1, 0)
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

select   ( case when IfNull(a.value,'0') = '0' then '0' 
              else '1' 
         end )
         *
         ( case when IfNull(b.value,'0') = '0' then '0' 
              else '1' 
         end ) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

select   cast( ( case when coalesce(a.value,'0') = '0' then '0' 
              else '1' 
         end ) as int )
         *
         cast( ( case when coalesce(b.value,'0') = '0' then '0' 
              else '1' 
         end ) as int ) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

对于MSSQL

convert

或

cast

功能可以使用：

select   convert(int, ( case when IsNull(a.value,'0') = '0' then '0' 
              else '1' 
         end ))
         *
         convert(int, ( case when IsNull(b.value,'0') = '0' then '0' 
              else '1' 
         end )) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

对于MySQL使用

IfNull

函数：

select nvl2(a.value, 1, 0) * nvl2(b.value, 1, 0)
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

select   ( case when IfNull(a.value,'0') = '0' then '0' 
              else '1' 
         end )
         *
         ( case when IfNull(b.value,'0') = '0' then '0' 
              else '1' 
         end ) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

select   cast( ( case when coalesce(a.value,'0') = '0' then '0' 
              else '1' 
         end ) as int )
         *
         cast( ( case when coalesce(b.value,'0') = '0' then '0' 
              else '1' 
         end ) as int ) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

对于PostGreSQL使用

coalesce

函数：

select nvl2(a.value, 1, 0) * nvl2(b.value, 1, 0)
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

select   ( case when IfNull(a.value,'0') = '0' then '0' 
              else '1' 
         end )
         *
         ( case when IfNull(b.value,'0') = '0' then '0' 
              else '1' 
         end ) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

select   cast( ( case when coalesce(a.value,'0') = '0' then '0' 
              else '1' 
         end ) as int )
         *
         cast( ( case when coalesce(b.value,'0') = '0' then '0' 
              else '1' 
         end ) as int ) as result
  from Table_A a
 inner join Table_B b
    on (a.ID = b.ID);

它们都给出了以下结果

result
  0
  0
  1
  0
  0

---

你的数据库引擎是什么？？？请在这里发布你希望看到的输出。另外，请以纯文本而不是图像的形式输入数据