postgresql unique key 创建语法 在PostgreSQL 中,创建唯一键的语法如下: ```sql CREATE TABLE table_name ( column1 datatype, column2 datatype, ... CONSTRAINT constraint_name UNIQUE (column_name) ); ``` 在上面的语法中,你需要将 `table_name` 替换为你要创建的表的名称,`column1`, `column2`, ...
UNIQUE [ NULLS [ NOT ] DISTINCT ] index_parameters | PRIMARY KEY index_parameters | REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE referential_action ] [ ON UPDATE referential_action ] } [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFER...
列'Id' 是索引'IX_TestUnique_SiteIdUrl' 的分区依据列。唯一索引的分区依据列必须是索引键的子集。 --方式2 ALTER TABLE [dbo].[TestUnique] ADD CONSTRAINT [IX_TestUnique_SiteIdUrl] UNIQUE NONCLUSTERED ( [SiteId] ASC, [Url] ASC )WITH (SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE...
CREATE TABLE COMPANY3( ID INT PRIMARY KEY NOT NULL, NAME TEXT NOT NULL, AGE INT NOT NULL UNIQUE, ADDRESS CHAR(50), SALARY REAL DEFAULT 50000.00 ); PRIMARY KEY 在设计数据库时,PRIMARY KEY 非常重要。 PRIMARY KEY 称为主键,是数据表中每一条记录的唯一标识。 设置UNIQUE 的列可能有多个,但是一张...
Not-null constraints are always copied to the new table. CHECK constraints will be copied only if INCLUDING CONSTRAINTS is specified. Indexes, PRIMARY KEY, and UNIQUE constraints on the original table will be created on the new table only if the INCLUDING INDEXES clause is specified. No distinct...
CREATE TABLE IF NOT EXISTS users( Id serial PRIMARY KEY, Name VARCHAR(10) NOT NULL, Code VARCHAR(20) NOT NULL, Ucode VARCHAR(20) NOT NULL, CreatedAt timestamptz DEFAULT current_timestamp, UpdatedAt timestamptz DEFAULT current_timestamp, CONSTRAINT users_Code_key UNIQUE(Code), CONSTRAINT ...
DETAIL:Key(a, b)=(1,1) alreadyexists. test=#insertintotbl_unique_indexvalues(1);INSERT01test=#insertintotbl_unique_indexvalues(1);INSERT01test=#insertintotbl_unique_indexvalues(1);INSERT01 示例2.唯一键会自动创建唯一索引 test=#truncatetabletbl_unique_index ;TRUNCATETABLEtest=#altertabletbl_...
CREATETABLEpublic.student(id int4NOTNULL,addressvarchar(255)NULL,emailvarchar(255)NULL,"name"varchar(255)NULL,CONSTRAINTstudent_pkeyPRIMARYKEY(id)); 接下来有两个事务执行批量插入操作,事务1先插入student3,再插入student4,如下: 代码语言:javascript ...
CREATE[UNIQUE]INDEX[CONCURRENTLY][[IFNOTEXISTS]name]ON[ONLY]table_name[USINGmethod]({column_name|(expression)}[COLLATEcollation][opclass[(opclass_parameter=value[,...])]][ASC|DESC][NULLS{FIRST|LAST}][,...])[INCLUDE(column_name[,...])][WITH(storage_parameter[=value][,...])][TABLESP...
table_constraint 可以是以下选项之一:[ CONSTRAINT constraint_name ] { UNIQUE ( column_name [, ... ] ) [ USING INDEX TABLESPACE tablespace ] | PRIMARY KEY ( column_name [, ... ] ) [ USING INDEX TABLESPACE tablespace ] | CHECK ( expression ) | FOREIGN KEY ( column_name [, ... ] ...