Oracle PL/SQL/Constraints/Add Foreign Key — различия между версиями

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Текущая версия на 10:01, 26 мая 2010

Add Foreign Primary Key

  
SQL> CREATE TABLE Employee(Employee_ID NUMBER(4) NOT NULL,
  2                   Employee_Name VARCHAR2(10),
  3                   JOB VARCHAR2(9),
  4                   Manager_ID NUMBER(4),
  5                   Start_Date DATE,
  6                   Salary NUMBER(7, 2),
  7                   COMM NUMBER(7, 2),
  8                   Deparment_ID NUMBER(2)
  9  );
Table created.
SQL>
SQL> INSERT INTO Employee VALUES (7369, "SMITH",  "CLERK",     7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"),  800, NULL, 20);
1 row created.
SQL> INSERT INTO Employee VALUES (7499, "ALLEN",  "SALESMAN",  7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600,  300, 30);
1 row created.
SQL> INSERT INTO Employee VALUES (7521, "WARD",   "SALESMAN",  7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250,  500, 30);
1 row created.
SQL> INSERT INTO Employee VALUES (7566, "JONES",  "MANAGER",   7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"),  2975, NULL, 20);
1 row created.
SQL> INSERT INTO Employee VALUES (7654, "MARTIN", "SALESMAN",  7698, TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30);
1 row created.
SQL> INSERT INTO Employee VALUES (7698, "BLAKE",  "MANAGER",   7839, TO_DATE("1-MAY-1981", "DD-MON-YYYY"),  2850, NULL, 30);
1 row created.
SQL> INSERT INTO Employee VALUES (7782, "CLARK",  "MANAGER",   7839, TO_DATE("9-JUN-1981", "DD-MON-YYYY"),  2450, NULL, 10);
1 row created.
SQL> INSERT INTO Employee VALUES (7788, "SCOTT",  "ANALYST",   7566, TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO Employee VALUES (7839, "KING",   "PRESIDENT", NULL, TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10);
1 row created.
SQL> INSERT INTO Employee VALUES (7844, "TURNER", "SALESMAN",  7698, TO_DATE("8-SEP-1981", "DD-MON-YYYY"),  1500,    0, 30);
1 row created.
SQL> INSERT INTO Employee VALUES (7876, "ADAMS",  "CLERK",     7788, TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20);
1 row created.
SQL> INSERT INTO Employee VALUES (7900, "JAMES",  "CLERK",     7698, TO_DATE("3-DEC-1981", "DD-MON-YYYY"),   950, NULL, 30);
1 row created.
SQL> INSERT INTO Employee VALUES (7902, "FORD",   "ANALYST",   7566, TO_DATE("3-DEC-1981", "DD-MON-YYYY"),  3000, NULL, 20);
1 row created.
SQL> INSERT INTO Employee VALUES (7934, "MILLER", "CLERK",     7782, TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10);
1 row created.
SQL>
SQL> CREATE TABLE Department(Deparment_ID NUMBER(2),
  2                          Department_Name VARCHAR2(14),
  3                          Location VARCHAR2(13)
  4  );
Table created.
SQL>
SQL> INSERT INTO Department VALUES (10, "ACCOUNTING", "NEW YORK");
1 row created.
SQL> INSERT INTO Department VALUES (20, "RESEARCH",   "DALLAS");
1 row created.
SQL> INSERT INTO Department VALUES (30, "SALES",      "CHICAGO");
1 row created.
SQL> INSERT INTO Department VALUES (40, "OPERATIONS", "BOSTON");
1 row created.
SQL>
SQL> alter table Employee add constraint Employee_pk primary key(Employee_ID);
Table altered.
SQL> alter table Department add constraint Department_pk primary key(Deparment_ID);
Table altered.
SQL> alter table Employee add constraint Employee_fk_Department foreign key(Deparment_ID) references Department;
Table altered.
SQL> alter table Employee add constraint Employee_fk_Employee foreign key(Manager_ID) references Employee;
Table altered.
SQL>
SQL> select * from Employee;
EMPLOYEE_ID EMPLOYEE_N JOB       MANAGER_ID START_DAT     SALARY       COMM DEPARMENT_ID
----------- ---------- --------- ---------- --------- ---------- ---------- ------------
       7369 SMITH      CLERK           7902 17-DEC-80        800                      20
       7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300           30
       7521 WARD       SALESMAN        7698 22-FEB-81       1250        500           30
       7566 JONES      MANAGER         7839 02-APR-81       2975                      20
       7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400           30
       7698 BLAKE      MANAGER         7839 01-MAY-81       2850                      30
       7782 CLARK      MANAGER         7839 09-JUN-81       2450                      10
       7788 SCOTT      ANALYST         7566 09-DEC-82       3000                      20
       7839 KING       PRESIDENT            17-NOV-81       5000                      10
       7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0           30
       7876 ADAMS      CLERK           7788 12-JAN-83       1100                      20
EMPLOYEE_ID EMPLOYEE_N JOB       MANAGER_ID START_DAT     SALARY       COMM DEPARMENT_ID
----------- ---------- --------- ---------- --------- ---------- ---------- ------------
       7900 JAMES      CLERK           7698 03-DEC-81        950                      30
       7902 FORD       ANALYST         7566 03-DEC-81       3000                      20
       7934 MILLER     CLERK           7782 23-JAN-82       1300                      10
14 rows selected.
SQL> select * from Department;
DEPARMENT_ID DEPARTMENT_NAM LOCATION
------------ -------------- -------------
          10 ACCOUNTING     NEW YORK
          20 RESEARCH       DALLAS
          30 SALES          CHICAGO
          40 OPERATIONS     BOSTON
SQL>
SQL>
SQL>
SQL> -- Using table aliases in joins
SQL>
SQL> SELECT e.Employee_ID, e.Start_Date,
  2         e.Employee_Name,d.Department_Name, d.Location
  3  FROM Employee e, Department d
  4  WHERE d.Deparment_ID = e.Deparment_ID;
EMPLOYEE_ID START_DAT EMPLOYEE_N DEPARTMENT_NAM LOCATION
----------- --------- ---------- -------------- -------------
       7369 17-DEC-80 SMITH      RESEARCH       DALLAS
       7499 20-FEB-81 ALLEN      SALES          CHICAGO
       7521 22-FEB-81 WARD       SALES          CHICAGO
       7566 02-APR-81 JONES      RESEARCH       DALLAS
       7654 28-SEP-81 MARTIN     SALES          CHICAGO
       7698 01-MAY-81 BLAKE      SALES          CHICAGO
       7782 09-JUN-81 CLARK      ACCOUNTING     NEW YORK
       7788 09-DEC-82 SCOTT      RESEARCH       DALLAS
       7839 17-NOV-81 KING       ACCOUNTING     NEW YORK
       7844 08-SEP-81 TURNER     SALES          CHICAGO
       7876 12-JAN-83 ADAMS      RESEARCH       DALLAS
EMPLOYEE_ID START_DAT EMPLOYEE_N DEPARTMENT_NAM LOCATION
----------- --------- ---------- -------------- -------------
       7900 03-DEC-81 JAMES      SALES          CHICAGO
       7902 03-DEC-81 FORD       RESEARCH       DALLAS
       7934 23-JAN-82 MILLER     ACCOUNTING     NEW YORK
14 rows selected.
SQL>
SQL>
SQL>
SQL>
SQL>
SQL>
SQL>
SQL>
SQL> drop table Department cascade constraints;
Table dropped.
SQL> drop table Employee cascade constraints;
Table dropped.
SQL>
SQL>



Alter table to add primary key and alter another table to add foreign key

   
SQL>
SQL>
SQL> create table subjects (
  2  subject_id    number not null,
  3  subject_name  varchar2(30) not null,
  4  description   varchar2(4000)
  5  )
  6  tablespace users;
Table created.
SQL>
SQL> alter table subjects
  2  add constraint pk_subjects primary key (subject_id);
Table altered.
SQL>
SQL> create table courses (
  2  course_id   number not null,
  3  course_name varchar2(60) not null,
  4  subject_id  number not null,
  5  duration    number(2),
  6  skill_lvl   varchar2(12) not null
  7  )
  8  tablespace users;
Table created.
SQL>
SQL> alter table courses
  2  add constraint pk_courses
  3  primary key (course_id);
Table altered.
SQL>
SQL> alter table courses
  2  add constraint fk_course_subj
  3  foreign key (subject_id) references subjects (subject_id);
Table altered.
SQL>
SQL> alter table courses
  2  add constraint ck_level check(
  3  skill_lvl in ("BEGINNER", "INTERMEDIATE", "ADVANCED")
  4  );
Table altered.
SQL>
SQL> drop table courses cascade constraints;
Table dropped.
SQL> drop table subjects cascade constraints;
Table dropped.
SQL>



Many to many using a primary-key and foreign-key relationship

    
SQL> CREATE TABLE Course
  2     (course_id        VARCHAR2(10) NOT NULL,
  3      course_name      VARCHAR2(20),
  4      PRIMARY KEY (course_id));
Table created.
SQL>
SQL> CREATE TABLE emp
  2     (stud_id    VARCHAR2(10) NOT NULL,
  3      stud_name  VARCHAR2(20),
  4      PRIMARY KEY (stud_id));
Table created.
SQL>
SQL> CREATE TABLE Enrolls_in
  2     (course_id  VARCHAR2(10) NOT NULL,
  3      stud_id    VARCHAR2(10) NOT NULL,
  4      PRIMARY KEY (course_id, stud_id),
  5      FOREIGN KEY (course_id) REFERENCES Course (course_id)
  6      ON DELETE CASCADE,
  7      FOREIGN KEY (stud_id) REFERENCES emp (stud_id)
  8      ON DELETE CASCADE);
Table created.
SQL>
SQL> drop table Course cascade constraints;
Table dropped.
SQL> drop table emp cascade constraints;
Table dropped.
SQL> drop table Enrolls_in;
Table dropped.
SQL>



One to many using a primary-key and foreign-key relationship

    
SQL>
SQL>
SQL> CREATE TABLE Programmer
  2     (lect_id    VARCHAR2(10) NOT NULL,
  3      lect_name  VARCHAR2(20),
  4      PRIMARY KEY (lect_id));
Table created.
SQL>
SQL> CREATE TABLE Course
  2     (course_id        VARCHAR2(10) NOT NULL,
  3      course_name      VARCHAR2(20),
  4      lect_id          VARCHAR(10),
  5      PRIMARY KEY (course_id),
  6      FOREIGN KEY (lect_id) REFERENCES Programmer (lect_id)
  7      ON DELETE CASCADE);
Table created.
SQL>
SQL> drop table Programmer cascade constraints;
Table dropped.
SQL> drop table Course cascade constraints;
Table dropped.



syntax to reference foreign key

    
SQL>
SQL>
SQL> --CREATE TABLE <table schema> OF <object schema>
SQL> --   (key attribute    NOT NULL,
SQL> --    attribute        attribute type,
SQL> --    PRIMARY KEY      (key attribute),
SQL> --    FOREIGN KEY      (key attribute)
SQL> --    REFERENCES <referenced table schema>(key attribute)
SQL> --    [ON DELETE][CASCADE|SET NULL]);
SQL>
SQL> --Example:
SQL>
SQL> CREATE TABLE emp
  2      (id         VARCHAR2(10) NOT NULL,
  3       course     VARCHAR2(10),
  4       year       VARCHAR2(4),
  5       PRIMARY KEY (id),
  6       FOREIGN KEY (id) REFERENCES Person ON DELETE CASCADE);

SQL>     FOREIGN KEY (id) REFERENCES Person ON DELETE CASCADE)
SP2-0734: unknown command beginning "FOREIGN KE..." - rest of line ignored.
SQL>
SQL>
SQL>
SQL>



Three foreign keys in a table

    
SQL> CREATE TABLE store (
  2    store_id VARCHAR2(12) CONSTRAINT store_pk PRIMARY KEY,
  3    store_name VARCHAR2(15),
  4    city VARCHAR2(25),
  5    state VARCHAR2(2),
  6    region VARCHAR2(2),
  7    zip VARCHAR2(5));
Table created.
SQL>
SQL> CREATE TABLE pc (
  2    pc_id VARCHAR2(12) CONSTRAINT prod_pk PRIMARY KEY,
  3    prod_desc VARCHAR2(15),
  4    upc NUMBER,
  5    brand VARCHAR2(12),
  6    category VARCHAR2(12),
  7    department VARCHAR2(12));
Table created.
SQL>
SQL> CREATE TABLE promotion (
  2    promo_id varchar2(12) CONSTRAINT promo_pk PRIMARY KEY,
  3    promo_name varchar2(15),
  4    promo_type varchar2(12));
Table created.
SQL>
SQL> CREATE TABLE FinancialYear (
  2    time_id DATE CONSTRAINT time_pk PRIMARY KEY,
  3    month NUMBER,
  4    quarter NUMBER,
  5    year NUMBER,
  6    season VARCHAR2(12));
Table created.
SQL>
SQL> CREATE TABLE SALES (
  2    time_id DATE NOT NULL CONSTRAINT time_fk             REFERENCES FinancialYear(time_id),
  3    store_id VARCHAR2(12) NOT NULL CONSTRAINT store_fk   REFERENCES store(store_id),
  4    pc_id VARCHAR2(12)  NOT NULL,
  5    promo_id VARCHAR2(12) NOT NULL CONSTRAINT promo_fk   REFERENCES promotion(promo_id),
  6    units NUMBER,
  7    dollars NUMBER,
  8    cost NUMBER,
  9    CONSTRAINT sales_pk PRIMARY KEY (time_id, store_id, pc_id, promo_id)
 10  );
Table created.
SQL>
SQL>
SQL> drop table sales;
Table dropped.
SQL> drop table FinancialYear;
Table dropped.
SQL> drop table promotion;
Table dropped.
SQL> drop table pc;
Table dropped.
SQL> drop table store;
Table dropped.