例如,您可以在資料列存放區資料表上使用 UNIQUE 條件約束,強制執行主索引鍵條件約束。 由於非唯一值將無法插入至資料列存放區資料表,因此 SQL Server 無法將值插入至資料行存放區。已排序的數據行存放區索引藉由啟用有效率的區段消除,已排序的叢集數據行存放區索引 (CCI) 藉由略過大量不符合查詢述詞的已排序數據...
Generally, it’s best practice to put unique constraints on a table to prevent duplicate rows. However, you may find yourself working with a database where duplicate rows have been created through human error, a bug in your application, or uncleaned data from external sources. This tutorial ...
UNIQUE DESC ON UNPIVOT DISK OPEN UPDATE DISTINCT OPENDATASOURCE UPDATETEXT DISTRIBUTED OPENQUERY USE DOUBLE OPENROWSET USER DROP OPENXML VALUES DUMP OPTION VARYING ELSE OR VIEW END ORDER WAITFOR ERRLVL OUTER WHEN ESCAPE OVER WHERE EXCEPT PERCENT ...
报错:Feature not supported: INSERT on conflict contains un-unique column 问题原因:INSERT ON CONFLICT中的conflict条件使用了非主键字段。 解决方法:INSERT ON CONFLICT中的conflict条件只能使用主键。 报错:Feature not supported: UPDATE with shard keys ...
Can I find out the "Listener" name through a SQL Server Query Can i give a rollup an Alias? Can I have a conditional JOIN? Can I have a primary key as a non-unique column Can I pass parameter to an ALTER DATABASE command Can I prevent deadlock during concurrent delete Can I print...
Duplicate values must be removed before a unique index can be created on the column or columns. Columns that are used in a unique index should be set to NOT NULL, because multiple null values are considered duplicates when a unique index is created....
column_name AS computed_column_expression [ PERSISTED [ NOT NULL ] ] [ [ CONSTRAINT constraint_name ] { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR = fillfactor ] [ WITH ( <index_option> [, ...n ] ) ] [ ON { partition_scheme_name ( partition_column_nam...
names must follow the rules foridentifiersand must be unique in the table. column_name can be up to 128 characters. column_name can be omitted for columns that are created with a timestamp data type. If column_name is not specified, the name of a timestamp column defaults to timestamp....
AI_FUNCTION_UNSUPPORTED_REQUEST, AI_FUNCTION_UNSUPPORTED_RETURN_TYPE, AI_QUERY_RETURN_TYPE_COLUMN_TYPE_MISMATCH, AI_SEARCH_EMBEDDING_COLUMN_TYPE_UNSUPPORTED_ERROR, AI_SEARCH_INDEX_TYPE_UNSUPPORTED_ERROR, AI_SEARCH_UNSUPPORTED_NUM_RESULTS_ERROR, ANALYZE_CONSTRAINTS_NOT_SUPPORTED, AVRO_DEFAULT_VALUES_UNSU...
in every row of each non-clustered index as part of the link that allows the Storage Engine to navigate from non-clustered index records to clustered index records to obtain column values for the query select list that aren't in the non-clustered index that was used (also commonly known ...