<列级约束>∷=[ CONSTRAINT约束名] I I NULL NOT NULL I PRIMARY KEY UNIQUE)[ CLUSTERED NONCLUSTERED]] I FOREIGN KEYI REFERENCES参照表[(参照列)] [ON DELETE CASCADE NO ACTION I ON UPDATE CASCADE NO ACTION 1] CHECK(逻辑表达式) <表级约束>∷=[ CONSTRA|NT约束名] I PRIMARY KEY UNIQUE J [ CLUSTERED| NONCLUSTERED]{(列名[ASC|DESC][,…]) FORE| GN KEY[(列名[,.])] REFERENCES参照表[(参照列[….])] ON DELETEL CASCADE NO ACTIONJI ON UPDATE I CASCADE NO ACTION JI CHECK(条件表达式) Designed by Tao Hongcai2021年2月23日13Designed by Tao Hongcai 2021年2月23日 13 <列级约束> ::=[ CONSTRAINT 约束名] { [ NULL | NOT NULL ] | [ { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] ] | [ [ FOREIGN KEY ] REFERENCES 参照表 [ (参照列) ] [ ON DELETE { CASCADE | NO ACTION } ] [ ON UPDATE { CASCADE | NO ACTION } ] ] | CHECK ( 逻辑表达式) } <表级约束 > ::= [ CONSTRAINT 约束名 ] { [ { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] {(列名[ASC | DESC] [ ,... ])} | FOREIGN KEY [ ( 列名 [ ,... ] ) ] REFERENCES 参照表 [ ( 参照列 [ ,... ] ) ] [ ON DELETE { CASCADE | NO ACTION } ] [ ON UPDATE { CASCADE | NO ACTION } ] | CHECK ( 条件表达式 ) }