![22
PL/SQL Block vs. Stored
Procedures
DECLARE
-- variable declaration
BEGIN
-- required executable
EXCEPTION
-- exception handling
END;
/
CREATE OR REPLACE PROCEDURE X
[(formal_parameters)] AS[IS]
-- variable declaration
BEGIN
-- required executable
EXCEPTION
-- exception handling
END X;
/
Anonymous PL/SQL Block Stored Procedure](https://image.slidesharecdn.com/chapter05built-insqlfunctions-240807075647-dd62375e/85/Chapter-05-Built-in-SQL-Functions-functions-22-320.jpg)
![27
Stored Procedures vs. Functions
CREATE OR REPLACE PROCEDURE X
[(parameters)] AS
-- variable declaration
BEGIN
-- required executable
EXCEPTION
-- exception handling
END X;
/
CREATE OR REPLACE FUNCTION X
[(formal_parameters)] RETURN
return_type IS[AS]
-- variable declaration
BEGIN
-- required executable
-- required RETURN statement
RETURN Z;
EXCEPTION
-- exception handling
END X;
/
Stored Procedure Function](https://image.slidesharecdn.com/chapter05built-insqlfunctions-240807075647-dd62375e/85/Chapter-05-Built-in-SQL-Functions-functions-27-320.jpg)
Chapter 05 (Built-in SQL Functions) functions
- 2. 2 Type of Functions Character Functions returning character values returning numeric values Numeric Functions Date Functions Conversion Functions Group Functions Error Reporting Other Functions
- 3. 3 Character Functions Returning Character Values CHR CONCAT INITCAP
- 4. 4 Character Functions Returning Character Values LOWER LPAD LTRIM NLS_INITCAP
- 5. 5 Character Functions Returning Character Values NLS_LOWER NLS_UPPER NLSSORT REPLACE RPAD
- 6. 6 Character Functions Returning Character Values RTRIM SOUNDEX SUBSTR SUBSTRB TRANSLATE UPPER
- 7. 7 Character Functions Returning Numeric Values ASCII INSTR INSTRB LENGTH LENGTHB
- 8. 8 Numeric Functions ABS ACOS ASIN ATAN ATAN2
- 9. 9 Numeric Functions CEIL COS COSH EXP FLOOR LN
- 10. 10 Numeric Functions LOG MOD POWER ROUND SIGN SIN
- 11. 11 Numeric Functions SINH SQRT TAN TANH TRUNC
- 12. 12 Date Functions ADD_MONTHS LAST_DAY MONTHS_BETWEEN NEW_TIME NEXT_DAY ROUND SYSDATE TRUNC
- 13. 13 Conversion Functions CHARTOROWID CONVERT HEXTORAW RAWTOHEX ROWIDTOCHAR
- 14. 14 Conversion Functions TO_CHAR TO_DATE TO_LABEL TO_MULTI_BYTE TO_NUMBER TO_SINGLE_BYTE
- 15. 15 Group Functions AVG COUNT GLB LUB
- 16. 16 Group Functions MAX MIN STDDEV SUM VARIANCE
- 17. 17 Error Reporting Functions SQLCODE SQLERRM
- 18. 18 Other Functions BFILENAME DECODE DUMP GREATEST GREATEST_LB LEAST
- 19. 19 Other Functions LEAST_LB NVL UID USER USERENV VSIZE
- 20. 20 Agenda Stored Procedures Functions Parameters Calling Stored Procedures & Functions Examples
- 21. 21 Stored Procedures Named PL/SQL blocks that Are stored in the database May have formal parameters Can return more than one value to the calling program Can be called from within other PL/SQL blocks as a PL/SQL statement by itself SQL> prompt
- 22. 22 PL/SQL Block vs. Stored Procedures DECLARE -- variable declaration BEGIN -- required executable EXCEPTION -- exception handling END; / CREATE OR REPLACE PROCEDURE X [(formal_parameters)] AS[IS] -- variable declaration BEGIN -- required executable EXCEPTION -- exception handling END X; / Anonymous PL/SQL Block Stored Procedure
- 23. 23 Parameters Parameters are optional MUST be given a data type, but must NOT be given a size Parameters have 3 modes IN Read-only within procedure/function Default mode (if mode is not explicitly specified) OUT Has an initial value of NULL within the procedure/function Ignores any values that the actual parameters have when the procedure/function is called Can read from and write to IN OUT Value of actual parameters are passed into procedure/function Can read from and write to
- 24. 24 Stored Procedure with Parameters CREATE OR REPLACE PROCEDURE X ( p_Parameter1 IN VARCHAR2, p_Parameter2 IN NUMBER, p_Parameter3 OUT VARCHAR2, p_Parameter4 OUT NOCOPY NUMBER, p_Parameter5 IN OUT NUMBER DEFAULT 1) AS -- variable declaration BEGIN -- required executable EXCEPTION -- exception handling END X; /
- 25. 25 set serveroutput on CREATE OR REPLACE PROCEDURE BoatReservations(p_Color IN VARCHAR2) AS CURSOR c_Reservations IS SELECT s.sname, r.day, r.bid FROM Sailor s, Reserve r, Boat b WHERE r.sid = s.sid AND r.bid = b.bid AND b.color = p_Color; v_Reservation c_Reservations%ROWTYPE; BEGIN OPEN c_Reservations; FETCH c_Reservations INTO v_Reservation; WHILE c_Reservations%FOUND LOOP DBMS_OUTPUT.PUT_LINE(v_Reservation.sname||' '||v_Reservation.day|| '||v_Reservation.bid); FETCH c_Reservations INTO v_Reservation; END LOOP; CLOSE c_Reservations; END BoatReservations; /
- 26. 26 Functions Named PL/SQL blocks that Are stored in the database May have formal parameters MUST use the keyword RETURN to return only one value RETURN passes control back to the calling program Required for functions Can be called from within other PL/SQL blocks as part of an expression SQL> prompt
- 27. 27 Stored Procedures vs. Functions CREATE OR REPLACE PROCEDURE X [(parameters)] AS -- variable declaration BEGIN -- required executable EXCEPTION -- exception handling END X; / CREATE OR REPLACE FUNCTION X [(formal_parameters)] RETURN return_type IS[AS] -- variable declaration BEGIN -- required executable -- required RETURN statement RETURN Z; EXCEPTION -- exception handling END X; / Stored Procedure Function
- 28. 28 CREATE OR REPLACE FUNCTION NextBusinessDate1 (p_Date DATE) RETURN DATE IS -- Variable that will contain the day that corresponds to the date parameter v_CurrentDay VARCHAR2(9); -- Variable that will contain the computed date of the next business day v_NextDate DATE; BEGIN /*First, determine the corresponding name of the day for the date parameter. It will be used later to determine the number of days by which the date should be incremented.*/ v_CurrentDay := UPPER(TRIM(TO_CHAR(p_Date, 'DAY'))); /*Based upon the name of the day and the business rule, calculate the next business date*/ IF v_CurrentDay = 'FRIDAY' THEN v_NextDate := p_Date + 3; ELSIF v_CurrentDay = 'SATURDAY' THEN v_NextDate := p_Date + 2; ELSE v_NextDate := p_Date + 1; END IF; -- Now, return the computed next business date to the calling program RETURN v_NextDate; END NextBusinessDate1;
- 29. 29 TRIM and TO_CHAR functions TRIM(string) Removes leading and trailing blanks TO_CHAR(date, ‘format’) See Table 5-4 for a list of valid formats The date field in the reservation table has been populated, but the weekday field is NULL. Write a query to populate the weekday field with the name of the day that corresponds to the date specified in the date field. UPDATE reservation SET weekday = TRIM(TO_CHAR(date, ‘DAY’)); NOTE: The ‘DAY’ format returns the name of the day with blanks padded on the right such that the length is 9 characters.
- 30. 30 Parameters May be passed by value or by reference IN by default, passed by reference OUT by default, passed by value IN OUT by default, passed by value Passing by reference results in faster performance NOCOPY A compiler hint to pass OUT & IN OUT parameters by reference Cannot use NOCOPY with IN parameters Ex: (P_outParameter IN OUT NOCOPY VARCHAR2) IS
- 31. 31 Parameters Formal parameters can have default values Formal parameters with default values must appear as the last items in the parameter list When calling a stored procedure or function, the actual arguments can be passed by positional or named notation
- 32. 32 Calling Stored Procedures & Functions With Parameters Stored Procedure from SQL> prompt CALL X(v_Variable1, …., v_VariableN); OR CALL X(p_Parameter1 => v_Variable1,…); EXEC X(v_Variable1,….,v_VariableN); Stored Procedure from within PL/SQL block EXECUTE IMMEDIATE ‘CALL X(……..)’; OR X(v_Variable1,….,v_VariableN); Function Used in an expression SELECT ElapsedDays(’01-JAN-1999’) FROM dual; Without Parameters If the stored procedure (or function) does not have parameters, then do not use parentheses to define or call the stored procedure (or function)