将GROUP BY添加到要检查重复的字段 您的查询可能看起来像

SELECT field1, field2, field3, ......   FROM table GROUP BY field1

将检查Field1以排除重复记录

或者你可能会问

SELECT *  FROM table GROUP BY field1

字段1的重复记录被排除在SELECT中

SELECT DISTINCT FIELD1, FIELD2, FIELD3 FROM TABLE1，如果这三列的值在表中都是唯一的。

例如，如果您的名字有多个相同的值，但所选列中的姓和其他信息不同，则该记录将包含在结果集中。

SELECT  c2.field1 ,
        field2
FROM    (SELECT DISTINCT
                field1
         FROM   dbo.TABLE AS C
        ) AS c1
        JOIN dbo.TABLE AS c2 ON c1.field1 = c2.field1

你可以用with子句来实现。

例如:

WITH c AS (SELECT DISTINCT a, b, c FROM tableName)
SELECT * FROM tableName r, c WHERE c.rowid=r.rowid AND c.a=r.a AND c.b=r.b AND c.c=r.c

这还允许您只选择WITH子句查询中选择的行。

这是一个简单的解决方法:

 WITH cte AS /* Declaring a new table named 'cte' to be a clone of your table */
 (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY val1 DESC) AS rn
 FROM MyTable /* Selecting only unique values based on the "id" field */
 )
 SELECT * /* Here you can specify several columns to retrieve */
 FROM cte
 WHERE rn = 1

对于SQL Server，您可以使用dense_rank和其他窗口函数来获取指定列上具有重复值的所有行和列。这里有一个例子……

with t as (
    select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r1' union all
    select col1 = 'c', col2 = 'b', col3 = 'a', other = 'r2' union all
    select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r3' union all
    select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r4' union all
    select col1 = 'c', col2 = 'b', col3 = 'a', other = 'r5' union all
    select col1 = 'a', col2 = 'a', col3 = 'a', other = 'r6'
), tdr as (
    select 
        *, 
        total_dr_rows = count(*) over(partition by dr)
    from (
        select 
            *, 
            dr = dense_rank() over(order by col1, col2, col3),
            dr_rn = row_number() over(partition by col1, col2, col3 order by other)
        from 
            t
    ) x
)

select * from tdr where total_dr_rows > 1

这是对col1、col2和col3的每个不同组合进行行计数。