Question

在更深层次的视图中编写视图和嵌套视图时，我有时会遗漏某些内容并最终丢失行/数据。如何检查两个不同表中的列是否与数据完全匹配？

示例：

select count(distinct table1.col1)
  from table1
 where table1.col1 not in (select distinct table2.col1 
                             from table2);

这将返回table1.col1中不在table2中的值的数量。但是，我不知道这是一个很好的解决方案，因为它不计算table1.col1中不存在的table2.col1值。

Answer 1

您可以使用两个EXCEPT个查询（或联合它们）来检查：

SELECT DISTINCT col1
FROM table1
EXCEPT
SELECT DISTINCT col1
FROM table2

这将显示table1中存在的值，但不显示table2中存在的值。然后再次运行，表格名称翻转为相反。

Answer 2

使用：

SELECT MAX(x.t1_missing_count) AS t1_missing_count, 
       MAX(x.t2_missing_count) AS t2_missing_count
  FROM (
SELECT COUNT(DISTINCT t1.col1) AS t1_missing_count,
       NULL AS t2_missing_count
  FROM TABLE_1 t1
 WHERE t1.col1 NOT IN (SELECT DISTINCT t2.col1 
                         FROM TABLE_2 t2)
UNION ALL
SELECT NULL,
       COUNT(DISTINCT t2.col1),           
  FROM TABLE_2 t2
 WHERE t2.col1 NOT IN (SELECT DISTINCT t1.col1 
                         FROM TABLE_1 t1)) x

Answer 3

select count(*) from (

select
table1.col1 from table1 left join table2 on table1.col1 = table2.col2
where table2.col1 is null

union

select table2.col1 from table2 left join table 1 on table2.col1 = table1.col1
where table1.col1 is null

)

Answer 4

declare @count int, @count2 int


select @count = count(distinct table1.col1)
  from table1
 where table1.col1 not in (select distinct table2.col1 
                             from table2)

select @count2 = count(distinct table2.col1)
  from table2
 where table2.col1 not in (select distinct table1.col1 
                             from table1)

select @count + @count2

验证两个不同表的两列完全匹配

4 个答案: