Frequently Asked Questions (FAQ) - SQL SELECT with DISTINCT on multiple columns 1.What is the purpose of using DISTINCT on multiple columns in SQL? DISTINCT on multiple columns eliminates rows where all selected fields are identical, ensuring unique combinations of the specified columns in the resu...
We can also useSELECT DISTINCTwith multiple columns. For example, -- select rows if the first name and country of a customer is uniqueSELECTDISTINCTcountry, first_nameFROMCustomers; Run Code Here, the command selects rows if combinations ofcountryandfirst_nameare unique. Meaning, the result wil...
If you specify multiple columns, the database engine evaluates the uniqueness of rows based on the combination of values in those columns. SQL DISTINCT operator examples Let’s take a look at some examples of using theDISTINCToperator in theSELECTstatement. ...
Distinct 是一个逻辑运算符。 无 Distinct Sort Distinct Sort 逻辑运算符将对输入进行扫描,删除重复项并按“Prope属性”窗格中的 distinct order by 谓词中指定的列进行排序。Distinct Sort 是一个逻辑运算符。 Distribute Streams Distribute Streams 运算符仅用于并行查询计划。 Distribute Streams...
SQL DISTINCT SELECT eliminates duplicate records from the results, return only distinct (different) values. DISTINCT aggregates: COUNT, AVG, MAX, etc. so, it operates on one column and does not support multiple columns Suppose that in a table a column may contain many duplicate values ...
SELECT DISTINCT GROUP BY PIVOT(当数据库兼容性级别为 110 或更高级别时。请参阅 SQL Server 2016 中数据库引擎功能的中断性变更。) HAVING 标量聚合 TOP LEFT、RIGHT、OUTER JOIN(允许使用 INNER JOIN) 子查询 应用于 CTE_query_definition 中 CTE 的递归引用的提示。下面...
Concatenate a string to use after the AS statement Concatenate distinct values to variable concatenate numbers (not add them) CONCATENATE ROW_NUMBER WITH LEADING ZERO FOR MAXIMUM OF 15 CHARACTERS Concatenate two columns using a trigger Concatenated Stored Procedure parameter value concatenating in the st...
报错:Update row with Key (id)=(xxxx) multiple times或者duplicate key value violates unique constraint 问题原因:违反唯一性约束,执行UPDATE、INSERT ON CONFLICT或INSERT操作时,主键存在重复数据。 解决方法: 若INSERT语法报错:可以改为INSERT INTO xx ON CONFLICT的语法,实现主键去重,详情请参见INSERT ON CONFLIC...
USEmaster; GO-- Create a link to the remote data source.-- Specify a valid server name for @datasrc as 'server_name'-- or 'server_name\instance_name'.EXEC sp_addlinkedserver @server = N'MyLinkServer', @srvproduct = N' ', @provider = N'SQLNCLI', @datasrc = N'server_name', ...
DELTA_CANNOT_USE_ALL_COLUMNS_FOR_PARTITION、PARTITIONS_ALREADY_EXIST、PARTITIONS_NOT_FOUND 428GU 數據表必須包含至少一個未隱含隱藏的數據行。 DELTA_EMPTY_DATA、DELTA_READ_TABLE_WITHOUT_COLUMNS、DELTA_TARGET_TABLE_FINAL_SCHEMA_EMPTY 428H2 在正在使用數據類型的內容中不支援數據類型。 DELTA_IDENTITY_COLUMNS...