Oracle PL/SQL Tutorial/PL SQL Statements/RAISE

Check condition first, then raise exception

SQL>
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
  2                    ENAME VARCHAR2(10),
  3                    JOB VARCHAR2(9),
  4                    MGR NUMBER(4),
  5                    HIREDATE DATE,
  6                    SAL NUMBER(7, 2),
  7                    COMM NUMBER(7, 2),
  8                    DEPTNO NUMBER(2));
Table created.
SQL>
SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK",    7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7521, "WARD",  "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER",  7839, TO_DATE("2-APR-1981",  "DD-MON-YYYY"), 2975, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10);
1 row created.
SQL>
SQL>
SQL> CREATE OR REPLACE TRIGGER secure_del_trigger
  2     BEFORE DELETE
  3     ON emp
  4     FOR EACH ROW
  5  DECLARE
  6     unauthorized_deletion EXCEPTION;
  7  BEGIN
  8     IF 1 = 1
  9     THEN
 10        RAISE unauthorized_deletion;
 11     END IF;
 12  EXCEPTION
 13     WHEN unauthorized_deletion
 14     THEN
 15        raise_application_error (-20500, "This record cannot be deleted");
 16  END;
 17  /
Trigger created.
SQL>
SQL> drop table emp;
Table dropped.

Define local exceptioon variable.

SQL>
SQL> SET SERVEROUTPUT ON SIZE 1000000
SQL>
SQL> -- Build an anonymous block that will trigger an error.
SQL> DECLARE
  2
  3
  4    my_error          EXCEPTION;
  5    PRAGMA EXCEPTION_INIT(my_error,-20001);
  6
  7  BEGIN
  8
  9    -- Raise the exception.
 10    RAISE my_error;
 11
 12  EXCEPTION
 13
 14    WHEN my_error THEN
 15      dbms_output.put_line("RAISE my_error"||CHR(10)
 16                           ||"SQLCODE ["||SQLCODE||"]"||CHR(10)
 17                           ||"SQLERRM ["||SQLERRM
 18                           ||"User defined error.]");
 19
 20  END;
 21  /
RAISE my_error
SQLCODE [-20001]
SQLERRM [ORA-20001: User defined error.]
PL/SQL procedure successfully completed.
SQL>

Raise the exception.

SQL>
SQL> SET SERVEROUTPUT ON SIZE 1000000
SQL>
SQL> -- Build an anonymous block that will trigger an error.
SQL> DECLARE
  2
  3    -- Define local exceptioon variable.
  4    my_error          EXCEPTION;
  5
  6  BEGIN
  7
  8
  9    RAISE my_error;
 10
 11  EXCEPTION
 12
 13    WHEN others THEN
 14      dbms_output.put_line("RAISE my_error"||CHR(10)
 15                           ||"SQLCODE ["||SQLCODE||"]"||CHR(10)
 16                           ||"SQLERRM ["||SQLERRM||"]");
 17
 18  END;
 19  /
RAISE my_error
SQLCODE [1]
SQLERRM [User-Defined Exception]
PL/SQL procedure successfully completed.
SQL>
SQL>

Re-raise the exception to indicate there is a problem

SQL> CREATE OR REPLACE PROCEDURE execDDL (ddl_string IN VARCHAR2)
  2     AUTHID CURRENT_USER IS
  3  BEGIN
  4     EXECUTE IMMEDIATE ddl_string;
  5  EXCEPTION
  6     WHEN OTHERS
  7     THEN
  8
  9        DBMS_OUTPUT.PUT_LINE ("Dynamic SQL Failure: " || SQLERRM);
 10        DBMS_OUTPUT.PUT_LINE ("   on statement: "" || ddl_string || """);
 11
 12        RAISE;
 13  END;
 14  /
Procedure created.
SQL>
SQL>