情况1：

Question

我有一种情况，我需要在更新的where条件中使用聚合函数声明和select语句。

示例：

情况1：

 Update test_table
 set ID_Number = 0
 where count(ID_Number)=1; /* Not possible with where */

注意：使用where子句无法使用上述脚本。

情况2：

例如，我有下表：测试

 ID_Number Column1  Column2
 --------------------------
  1          XYZ      ZYX
  1          MMM      NNN
  2          III      JJJ
  3          AAA      BBB
  3          CCC      DDD

现在我只需要显示那些ID_Number出现两次的记录。

预期结果：

 ID_Number   Column1    Column2
 ------------------------------
  1           XYZ        ZYX
  1           MMM        NNN
  3           AAA        BBB
  3           CCC        DDD

我的尝试：

 select * from Test
 group by ID_Number,Column1,Column2 
 having count(ID_Number)>1;

注意：这对我没有任何帮助。

Answer 1

SET NOCOUNT ON;
DECLARE @Test TABLE
(
   ID_Number INT NOT NULL,
   Column1 VARCHAR(50),
   Column2 VARCHAR(50)
);
INSERT INTO @Test VALUES (1, 'XYZ', 'ZYX');
INSERT INTO @Test VALUES (1, 'MMM', 'NNN');
INSERT INTO @Test VALUES (2, 'III', 'JJJ');
INSERT INTO @Test VALUES (3, 'AAA', 'BBB');
INSERT INTO @Test VALUES (3, 'CCC', 'DDD');

-- Situation #1
;WITH cte AS
(
   SELECT ID_Number
   FROM   @Test
   GROUP BY ID_Number
   HAVING COUNT(*) = 1
)
UPDATE ts
SET    ts.ID_Number = 0
FROM   @Test ts
INNER JOIN cte
        ON cte.ID_Number = ts.ID_Number;

-- Situation #2
;WITH cte AS
(
   SELECT ID_Number
   FROM   @Test
   GROUP BY ID_Number
   HAVING COUNT(*) > 1
)
SELECT ts.*
FROM   @Test ts
INNER JOIN cte
        ON cte.ID_Number = ts.ID_Number;

输出是问题中显示的“预期结果”。

对于这两种情况，CTE都会获得多次显示的ID_Number值，并且该值列表用于过滤主SELECT或UPDATE。

Answer 2

试试这个：

情况1：

更新你可以使用Common Table Expressions

Update test_table
 set ID_Number = 0
 where ID_Number IN (
select tst.ID_Number from test_table tst join
(
select ID_Number,COUNT(*) as CNT from test_table
GROUP BY  ID_Number)d
 ON d.ID_Number=tst.ID_Number
 where d.CNT=1
)

情况2：

select tst.ID_Number,Column1,Column2 from test_table tst join
(
select ID_Number,COUNT(*) as CNT from test_table
GROUP BY  ID_Number)d
 ON d.ID_Number=tst.ID_Number
 where d.CNT>1

SQL Fiddle

Answer 3

首先查看情境2 您的查询以获得所需的输出，如下所示：

SELECT * FROM Test 
WHERE ID_Number IN (select ID_Number from Test
                group by ID_Number
                having count(ID_Number)>1)

现在查看情境1 ，您可以编写更新列的UPDATE查询：ID_Number = 0仅适用于ID_Number根据您在更新查询中声明的记录一次的记录。您可以按如下方式修改更新查询：

Update test_table
set ID_Number = 0
FROM test_table
WHERE ID_Number IN (select ID_Number from Test
group by ID_Number
having count(ID_Number) = 1

Answer 4

这就是我要做的事情：

with cte as (
   select *, count(*) over (partition by ID_Number) as c
   from test_table
)
select *
from cte
where c > 1

使用where子句聚合函数

情况1：

情况2：

4 个答案: