The FOREIGN KEY Clause : Foreign Key « Constraints « SQL Server / T-SQL Tutorial

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SQL Server / T-SQL Tutorial » Constraints » Foreign Key 
7. 3. 1. The FOREIGN KEY Clause
[CONSTRAINT c_name]
      [[FOREIGN KEY] (col_name1 [{, col_name2...]])
      REFERENCES table_name (col_name3 [{, col_name4...])
        [ON DELETE {NO ACTION|CASCADE|SET NULL|SET DEFAULT}]
         [ON UPDATE {NO ACTION|CASCADE|SET NULL|SET DEFAULT}]

14>
15CREATE TABLE employee (emp_no INTEGER NOT NULL,
16>               emp_fname CHAR(20NOT NULL,
17>               emp_lname CHAR(20NOT NULL,
18>               dept_no CHAR(4NULL,
19>       CONSTRAINT prim_empl PRIMARY KEY (emp_no))
20> GO
1>
2CREATE TABLE myProject (
3>     emp_no INTEGER NOT NULL,
4>     project_no CHAR(4NOT NULL,
5>     job CHAR (15NULL,
6>     enter_date DATETIME NULL,
7>     CONSTRAINT prim_works PRIMARY KEY (emp_no, project_no),
8>     CONSTRAINT foreign_works FOREIGN KEY (emp_noREFERENCES employee (emp_no))
9> GO
1>
2>
3> drop table myProject;
4> GO
1>
2> drop table employee;
3> GO
1>
7. 3. Foreign Key
7. 3. 1. The FOREIGN KEY Clause
7. 3. 2. FOREIGN KEY Constraints
7. 3. 3. A statement that adds a foreign key constraint
7. 3. 4. ON DELETE and ON UPDATE Options
7. 3. 5. Adding a FOREIGN KEY to the Employees Table
7. 3. 6. Re-creating the FOREIGN KEY with NO ACTION (Implicitly)
7. 3. 7. Referential Constraints
7. 3. 8. Cascading Updates and Deletes
7. 3. 9. Supporting Basic Referential Integrity with Foreign Keys
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