Now we have realized that custid 1, 4 & 5 are duplicate. The self-join statement accompanied by delete statement will give us the desired output of keeping the last duplicate record by eliminating all the previous duplicate records. We will use theCommon Table Expression (CTE)and put the Sel...
SQL Server 有各种强制执行实体完整性的机制,包括索引、唯一约束、主键约束和触发器。 写在前面 参考官方文档https://support.microsoft.com/zh-cn/help/139444/how-to-remove-duplicate-rows-from-a-table-in-sql-serverlink 原文摘录 需要检查是否是除了id列之外的整行重复,请对比所有列之后,选择需要保留的行 只...
SELECTDISTINCT*INTOduplicate_tableFROMoriginal_tableGROUPBYkey_valueHAVINGCOUNT(key_value) >1DELETEoriginal_tableWHEREkey_valueIN(SELECTkey_valueFROMduplicate_table)INSERToriginal_tableSELECT*FROMduplicate_tableDROPTABLEduplicate_table 此脚本按给定顺序执行以下操作: ...
在SQL Server 中,去重通常可以通过使用DISTINCT关键字、GROUP BY子句或者ROW_NUMBER()函数来实现。我们接下来将详细说明这些方法。 2. 使用DISTINCT DISTINCT关键字用于从结果集中返回不同的值。它通常用于单列或多列的查询中,以消除重复结果。 示例代码: SELECTDISTINCTcolumn1,column2FROMyour_table; 1. 2. 上面的...
1--You can preserve duplicate rows by making them unique with the ROW_NUNBER() Windowing Function.2WITHIntersectAllAS3(4SELECT5ROW_NUMBER()OVER(PARTITIONBYCol1, Col2ORDERBY(SELECT0))ASRowNumber,6Col1,7Col28FROMt1910INTERSECT1112SELECT13ROW_NUMBER()OVER(PARTITIONBYCol1, Col2ORDERBY(SELECT0...
CREATE TABLE TestBatch (ColA INT PRIMARY KEY, ColB CHAR(3)); GO INSERT INTO TestBatch VALUES (1, 'aaa'); INSERT INTO TestBatch VALUES (2, 'bbb'); INSERT INTO TestBatch VALUES (1, 'ccc'); -- Duplicate key error. GO SELECT * FROM TestBatch; -- Returns rows 1 and 2...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance SQL database in Microsoft Fabric Is a data type that exposes automatically generated, unique binary numbers within a database. rowversion is generally used as a mechanism for version-stamping table rows. The storage size is 8...
SQL Server selects specific rows to compress according to their last update time. For example, if rows are changing frequently during a two-hour period of time, you could set COMPRESSION_DELAY = 120 Minutes to ensure updates are completed before SQL Server compresses the row. For a disk-...
SELECT [ ALL | DISTINCT ] TOP (expression) < select_list > < select_list > ::= { * | { table_name | table_alias }.* | { column_name | expression } [ [ AS ] column_alias ] } [ ,...n ] Arguments ALL Specifies that duplicate rows can appear in the result set. ALL is ...
CREATE TABLE TestBatch (Cola INT PRIMARY KEY, Colb CHAR(3)); GO INSERT INTO TestBatch VALUES (1, 'aaa'); INSERT INTO TestBatch VALUES (2, 'bbb'); INSERT INTO TestBatch VALUES (1, 'ccc'); -- Duplicate key error. GO SELECT * FROM TestBatch; -- Returns rows 1 and 2. GO Dat...