-- 查询重复数据并统计每个重复数据的数量SELECTcol1,col2,...,COUNT(*)ASduplicatesFROMtable_nameGROUPBYcol1,col2,...HAVINGCOUNT(*)>1; 1. 2. 3. 4. 5. 代码解释: SELECT col1, col2, ...:选择需要查询的列,以便找到重复的数据。 COUNT(*) AS duplicates:统计每个重复数据的数量,并将结果命名...
在SELECT语句中,我们使用MIN函数选择了保留数据的主键。最后,我们使用DELETE语句删除了重复数据,保留了一条数据。在DELETE语句中,我们使用了NOT IN子句来排除要保留的数据的主键。 3. 清理临时表 最后,我们需要清理临时表,以释放资源。可以通过以下步骤来完成这个任务: -- 删除临时表#Duplicates和#ToKeepDROPTABLE#Dup...
DELETE FROM table_name WHERE column_name IN ( SELECT column_name FROM table_name GROUP BY column_name HAVING COUNT(*) > 1 ); 方法三:使用ROW_NUMBER()函数 可以使用ROW_NUMBER()函数给每条记录赋予一个唯一的行号,然后根据行号来删除重复的记录。
We can delete one or more records (commonly known as rows) from a table using the delete statement. The Delete statement removes some or all data (rows) from a table. According to Microsoft documentation, the Delete statement removes one or more rows from a table or view in SQL Server. ...
2 a join customers2 b on a.custid <> b.custid and a.CustName = b.CustName and a.CustCity = b.CustCity and a.Passport_Number = b.Passport_Number ) Delete from Customers2 where custid in (select Customer_ID from Duplicates) and custid <> (select min(Customer_ID) from Duplicates)...
1,删除表中重复数据,仅保留重复数据id最小的 delete from yyd_wykl_goodsInfo where skuId in (select skuId from (select...from (select min(id) as id from yyd_wykl_goodsInfo group by skuId having count(skuId )>1) b); 2,查找表中多余的重复记录...(多个字段),不包含id最小的记录 select...
在SQL中删除重复的记录,通常需要使用临时表和ROW_NUMBER()函数。以下是一个示例: WITH CTE AS ( SELECT *, ROW_NUMBER() OVER (PARTITION BY column1, column2, ... ORDER BY (SELECT NULL)) AS RowNum FROM your_table ) DELETE FROM CTE
SELECT id,name,age, ROW_NUMBER() OVER (PARTITION BY id, name, age ORDER BY id) AS Duplicates FROM Test ) DELETE FROM CTE WHERE Duplicates > 1 GO Now check the table to make sure duplicates are being removed from table. Related:
DELETE FROM ( SELECT id, ROW_NUMBER() OVER (PARTITION BY name, age ORDER BY id) AS row_num FROM students ) AS duplicates WHERE row_num > 1; 在这个例子中,使用`ROW_NUMBER()`函数为重复的记录分配行号,然后删除行号大于1的记录。 综上所述,DELETE语句是SQL中常用的命令之一,用于删除数据库中的...
开始我们拿sql到数据库查询平台查库执行计划,无奈这个平台有bug,delete语句无法查看,所以我们改成select,“应该”是一样。这个“应该”加了双引号,导致我们走了一点弯路。EXPLAIN SELECT * from t_table_1 where task_id in (select id from t_table_2 where uid = 1) explain后可以看到是走了索引的 到这里...