UNIQUE Constraint The UNIQUE constraint ensures that all values in a column are distinct. For example, in the following CREATE TABLE statement, CREATE TABLE Customer (SID integer UNIQUE, Last_Name varchar (30), First_Name varchar(30));column "SID" has a UNIQUE constraint, and hence cannot...
CREATE UNIQUE INDEX for Unique Values If we want to create indexes for unique values in a column, we use theCREATE UNIQUE INDEXconstraint. For example, -- create unique indexCREATEUNIQUEINDEXcollege_indexONColleges(college_code); Run Code Here, the SQL command creates a unique index namedcollege...
Based on your desired output modified condition forCat_1_Count.
INSERT INTO TestTable VALUES (1); GO 示例A 会话1: 在一个事务中执行一个 SELECT 语句。 由于 HOLDLOCK 锁提示的原因,此语句将获取并保留一个对此表的意向共享 (IS)锁(此例中忽略行锁和页锁)。 IS 锁只能在分配给事务的分区中获取。 对于此示例,假定 IS 锁是在 ID 为 7 的分区中获取。...
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 ...
In this example a given column (the columnname) was made unique by adding the clauseUNIQUEat the end of the column definition (name VARCHAR(100)UNIQUE). This new table (in our example:product) will contain the column (in our example:name) that stores unique values in rows. ...
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 ...
指定大容量导入操作忽略表上的任何约束。 默认情况下,INSERT检查唯一约束和检查约束和主键和外键约束。 为批量导入操作指定IGNORE_CONSTRAINTS时,INSERT必须忽略目标表上的这些约束。 不能禁用UNIQUE、PRIMARY KEY或NOT NULL约束。 如果输入数据包含违反约束的行,可能需要禁用CHECK和FOREIGN KEY约束。 通过禁用CHECK和FOREIGN...
UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR = fillfactor | WITH ( <index_option> [ ,... n ] ) ] [ ON { partition_scheme_name ( partition_column_name ) | filegroup | "default" } ] | [ FOREIGN KEY ] REFERENCES referenced_table_name [ ( ref_column ) ] [ ON DELETE...
syntaxsql Kopiera CREATE [ UNIQUE ] [ CLUSTERED | NONCLUSTERED ] INDEX index_name ON <object> ( column [ ASC | DESC ] [ ,...n ] ) [ INCLUDE ( column_name [ ,...n ] ) ] [ WHERE <filter_predicate> ] [ WITH ( <relational_index_option> [ ,...n ] ) ] [ ON { ...