下列哪个FOREIGN KEY约束条件关键字用来标识表和父表中的列?()
在SQL中,primary key为 约束的关键字,foreign key为 __________约束的关键字。
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下列SQL句中,能够实现参照完整性控制的语句是()。A. FOREIGN KEYB. PRIMARY KEYC. REFERENCESD. FOREIGN KEY 和REFERENCES
使用DELETE语句删除表中的所有数据以后,表中的标识列将被重置为种子的值。()此题为判断题(对,错)。
Which statement explicitly names a constraint? ()A. ALTER TABLE student_grades ADD FOREIGN KEY (student_id) REFERENCES students (student_id);B. ALTER TABLE student_grades ADD CONSTRAINT NAME = student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);C. ALTER TABLE student_grades ADD CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);D. ALTER TABLE student grades ADD NAMED CONSTRAINT student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);E. ALTER TABLE student grades ADD NAME student_id_fk FOREIGN KEY (student_id) REFERENCES students (student_id);
SQL定义功能中,用CREATE TABLE建立表时,FOREIGN KEY...REFERENCES…短语的含义是A.说明主关键字B.建立表之间的联系C.说明有效性规则D.说明根据指定数组的内容建立表
_____A.PRIMARY KEY (部门号) NOT NULL UNIQUEB.PRIMARY KEY (部门名) UNIQUEC.FOREIGN KEY (负责人) REFERENCES 员工 (姓名)D.FOREIGN KEY (负责人) REFERENCES 员工 (员工号)A.B.C.D.
下列SQL语句中,能够实现参照完整性控制的语句是——。A.PRIMARY KEYB.FOREIGN KEYC.FOREIGN KEY和REFERENCESD.REFERENCES