1. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 20051 OCL4 Oracle 10g: SQL & PL/SQL Session #6 Matthew P. Johnson CISDD, CUNY June, 2005

2. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 2 Agenda Last time:  Programming for SQL  Pro*C, JDBC This time:  SPs in PL/SQL Next time:  More PL/SQL  Triggers

3. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 3 Step back Recall basic problem: need SQL plus stronger programming lang   need to connect the two langs In all these cases (and in the web app case), idea is: put SQL in (traditional-lang) programs Another way: put programs in SQL  i.e., store programs on the DBMS  “stored procedures”

4. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 4 Next topic: SPs “Persistent, Stored Modules” / “Stored Procedures / “PL/SQL programs” (in Oracle) Another way to connect application programming language and SQL Supports usual things:  Declare, set vars to vals of expressions  Print output  Define (optional) procedures, functions  Cursors PL/SQL can compute n!

5. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 5 Integration with SQL DECLARE l_book_count INTEGER; BEGIN SELECT COUNT(*) INTO l_book_count FROM books WHERE author LIKE '%FEUERSTEIN, STEVEN%'; DBMS_OUTPUT.PUT_LINE ( 'Steven has written (or co-written) ' || l_book_count || ' books.'); -- Oh, and I changed my name, so... UPDATE books SET author = REPLACE (author, 'STEVEN', 'STEPHEN') WHERE author LIKE '%FEUERSTEIN, STEVEN%'; END; DECLARE l_book_count INTEGER; BEGIN SELECT COUNT(*) INTO l_book_count FROM books WHERE author LIKE '%FEUERSTEIN, STEVEN%'; DBMS_OUTPUT.PUT_LINE ( 'Steven has written (or co-written) ' || l_book_count || ' books.'); -- Oh, and I changed my name, so... UPDATE books SET author = REPLACE (author, 'STEVEN', 'STEPHEN') WHERE author LIKE '%FEUERSTEIN, STEVEN%'; END;

6. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 6 PL/SQL “Procedural Language/SQL”  Oracle’s language for stored procedures Simple, interpreted, procedural language But Pascal-like:  BEGIN END, not { }  AND OR, not && ||  vars defined at top of procedure  how return works

7. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 7 PL/SQL Generally speaking can be used wherever SQL can be  sqlplus  embeded SQL  JDBC Can store programs in files (.sql), run later  @myprog.sql runs code in myprog.sql

8. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 8 Scripting languages Big problems v. small problems Big solutions v. small solutions Programming languages:  C/C++, Java, etc. Scripting languages:  PL/SQL, Perl, PHP, Unix shell, DOS batch files, Python, Excel macros, VBA, JavaScript Usual properties of scripting languages:  Interpreted Though now compiled to bytecode or (optionally) to native  Don’t require functions/procedures Though now supported  Weakly typed Lots of auto-conversion

9. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 9 PL/SQL: Hello, World http://pages.stern.nyu.edu/~mjohnson/oracle/plsql/hello.sql BEGIN -- print out message DBMS_OUTPUT.PUT_LINE('Hello World, from PL/SQL'); END; / BEGIN -- print out message DBMS_OUTPUT.PUT_LINE('Hello World, from PL/SQL'); END; /

10. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 10 Hello, World Try again… SET SERVEROUTPUT ON BEGIN -- print out message DBMS_OUTPUT.PUT_LINE('Hello World, from PL/SQL'); END; / SET SERVEROUTPUT ON BEGIN -- print out message DBMS_OUTPUT.PUT_LINE('Hello World, from PL/SQL'); END; /

11. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 11 Use start-up script Go to \sqlplus\admin\glogin.sql Start-up script run upon login to SQL*Plus Add “SET SERVEROUTPUT ON” to it If running non-i version of SQL*Plus, also looks in current dir for login.sql script

12. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 12 How to run code The code before ended with a forward slash Not SQL and not PL/SQL – just for SQL*Plus to tell it to run the code entered Must go on its own line  O.w., will be ignored and then interpreted as part of code, causing an error To call a procedure in SQL*Plus, can also use execute/exec: exec DBMS_OUTPUT.PUT_LINE('Hello World, from PL/SQL')

13. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 13 How to run code EXEC is just short-hand: SQL> exec dbms_output.put_line('hi '); dbms_output.put_line('there'

14. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 14 PL/SQL operators/symbols ;end statement %attribute indicator (cursor attributes like %ISOPEN and indirect declaration attributes like %ROWTYPE :host variable indicator <> and !=not-equal-to =equal-to :=assignment op ** exponentiation operator --, /* and */, rem comments

15. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 15 Var names identifiers limited to 30 alpha-num chars  Must start with letter, $, _, or # E.g.: abc, $a$, $$$ PL/SQL is case INsensitive  abc, ABC, AbC all the same  Unless you use double-quotes… Also supports constants:  Varname datatype CONSTANT := val;

16. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 16 Literals Numbers: 123, 12.3, 3.05E19, 12e-5, null String: 'abc', 'AbC', null  String comparison is case-SENSitive Boolean: true, false, null  true != ‘true’ No date literals, as in regular SQL  To_date('31-JAN-94') Escape single-quotes in strings with two single- quotes 'it''s'  it's ''''''  ''

17. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 17 Blocks PL/SQL is a block-structured language Block = seq. of instructions, with scope Can have anonymous blocks And named blocks  Procedures  Functions

18. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 18 Structure of a block As in Pascal, var declars precede body header--if named DECLARE--optional --var declarations BEGIN --executable statements --queries/updates, etc. EXCEPTION--optional --catch exceptions END; /--to execute header--if named DECLARE--optional --var declarations BEGIN --executable statements --queries/updates, etc. EXCEPTION--optional --catch exceptions END; /--to execute

19. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 19 PL/SQL code examples One example:  Likes(drinker, beverage) Another example:  http://pages.stern.nyu.edu/~mjohnson/oracle/plsql/age.sql http://pages.stern.nyu.edu/~mjohnson/oracle/plsql/age.sql BEGIN INSERT INTO Likes VALUES(‘Izzy', ‘milk'); DELETE FROM Likes WHERE drinker = ‘Izzy' AND beverage = ‘Beaujolais Nouveau '; COMMIT; END; / BEGIN INSERT INTO Likes VALUES(‘Izzy', ‘milk'); DELETE FROM Likes WHERE drinker = ‘Izzy' AND beverage = ‘Beaujolais Nouveau '; COMMIT; END; /

20. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 20 Procedures Stored database objects that use a PL/SQL statement(s) in their body Create/drop similar to other SQL objects: CREATE PROCEDURE ( ) AS ; CREATE PROCEDURE ( ) AS ; DROP PROCEDURE ; CREATE OR REPLACE PROCEDURE ( ) AS ; CREATE OR REPLACE PROCEDURE ( ) AS ;

21. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 21 Example procedure Define the procedure: Now we can call it: CREATE PROCEDURE testProcedure AS BEGIN INSERT INTO Student VALUES (5, 'Joe'); END; CREATE PROCEDURE testProcedure AS BEGIN INSERT INTO Student VALUES (5, 'Joe'); END; EXEC testProcedure

22. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 22 More details on procedures Parameter list has name-mode-type triples: Modes: IN, OUT, or IN OUT  Fulfills role similar to pass-by-value v. pass-by- reference  Default is IN Types must match, so can get exact field type: relation.attribute%TYPE

23. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 23 Procedure I/O example A procedure to take a beer and price and add it to Joe's menu: Sells(bar, beer, price) CREATE PROCEDURE izzyMenu( b IN char(20), p IN double) AS BEGIN INSERT INTO Sells VALUES('Izzy''s', b, p); END; / CREATE PROCEDURE izzyMenu( b IN char(20), p IN double) AS BEGIN INSERT INTO Sells VALUES('Izzy''s', b, p); END; / Are these the right types?

24. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 24 Procedure I/O example A procedure to take a beer and price and add it to Joe's menu: Sells(bar, beer, price) CREATE PROCEDURE izzyMenu( b IN Sells.beer%TYPE, p IN Sells.price%TYPE) AS BEGIN INSERT INTO Sells VALUES('Izzy''s', b, p); END; / CREATE PROCEDURE izzyMenu( b IN Sells.beer%TYPE, p IN Sells.price%TYPE) AS BEGIN INSERT INTO Sells VALUES('Izzy''s', b, p); END; /

25. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 25 Larger procedure e.g. CREATE or replace PROCEDURE hike_prices(old_price number, new_price out number, percent_hike number := 5) is Begin new_price := old_price + old_price * percent_hike/100; End; / CREATE or replace PROCEDURE hike_prices(old_price number, new_price out number, percent_hike number := 5) is Begin new_price := old_price + old_price * percent_hike/100; End; /

26. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 26 Call the procedure But how to use to modify table data? Convert to a function Declare currprice number := 20; newprice number; Begin hike_prices(currprice,newprice,5); dbms_output.put_line(newprice); End; Declare currprice number := 20; newprice number; Begin hike_prices(currprice,newprice,5); dbms_output.put_line(newprice); End;

27. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 27 Functions Like procedures but with return values Big strength: can be called from SQL itself CREATE FUNCTION ( ) RETURN type AS BEGIN END; CREATE FUNCTION ( ) RETURN type AS BEGIN END; DROP FUNCTION ;

28. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 28 Function example http://pages.stern.nyu.edu/~mjohnson/oracle/plsql/maxval.sql CREATE OR REPLACE FUNCTION maxval(a IN int, b IN int) RETURN int AS BEGIN IF a > b THEN RETURN a; ELSE RETURN b; END IF; END maxval; CREATE OR REPLACE FUNCTION maxval(a IN int, b IN int) RETURN int AS BEGIN IF a > b THEN RETURN a; ELSE RETURN b; END IF; END maxval; INSERT INTO R VALUES('abc', maxval(5,10));

29. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 29 Hike function Now can use directly in update statements NB: had to use different name for ftn  Same namespace for ftns & procs, although different CREATE or replace FUNCTION hike_pricesf(old_price number, percent_hike number := 5) return number is Begin return old_price + old_price * percent_hike/100; End; / CREATE or replace FUNCTION hike_pricesf(old_price number, percent_hike number := 5) return number is Begin return old_price + old_price * percent_hike/100; End; /

30. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 30 How to run scripts Don’t want to type ftns into sqlplus by hand Define them in a.sql file In sqlplus, execute.sql file  Runs commands in file  Here, defines function Now, we can call functions See http://pages.stern.nyu.edu/~mjohnson/oracle/plsql/plsql.txt SQL> @maxval.sql SQL> exec DBMS_OUTPUT.PUT_LINE (maxval(5,10))

31. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 31 How to run scripts Can also use the start command: If no file extension is given,.sql is assumed Can use full paths: Scripts can call other scripts Use @ for current dir, @@ for dir of current script Scripts are not (by default) echoed. Can use: SQL> START maxval.sql SQL> @c:\somewhere\maxval.sql SQL> SET ECHO ON

32. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 32 Calling functions and procedures Procedures can simple executed, ftns can’t How to just call a ftn? Can use dbms_output, as seen Can also select the ftn value from dual SQL> select(wordcount('hi there') from dual;

33. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 33 Stored ftns & procs persist Once a function or procedure is created, it persists until it’s dropped Stored procs are stored in the DB itself  In user_procedures in Oracle Also, can describe ftns and procs: CREATE OR REPLACE FUNCTION … SELECT object_name from user_procedures; SQL> describe wordcount

34. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 34 Look up procedures, functions In Oracle, functions & procedures in user_procedures: Also, can describe ftns and procs: SELECT object_name from user_procedures; SQL> describe wordcount

35. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 35 Getting errors Simply says: To get actual errors, say SHOW ERR(ORS) Can also get errors per object: Warning: must get object type right! Can also look at user_errors tbl directly Warning: Function created with compilation errors. SQL> show errors function wordcount

36. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 36 More on PL/SQL O’Reilly’s Oracle PL/SQL Programming:  http://www.unix.org.ua/orelly/oracle/prog2/ http://www.unix.org.ua/orelly/oracle/prog2/  This lecture somewhat follows 3 rd edition of this book PL/SQL Reference & Tutorial:  http://www.ilook.fsnet.co.uk/ora_sql/sqlmain2.htm http://www.ilook.fsnet.co.uk/ora_sql/sqlmain2.htm Introduction to PL/SQL:  http://www.geocities.com/cliktoprogram/plsql/introduction.html http://www.geocities.com/cliktoprogram/plsql/introduction.html Oracle FAQ's Script and Code Exchange:  http://www.orafaq.com/scripts/ http://www.orafaq.com/scripts/

37. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 37 Break Lab 5, lab 6 (exercises 1-3)

38. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 38 Agenda A little more PL/SQL lecture Go through some exercises More PL/SQL lab… Later: go through some PL/SQL exercises…

39. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 39 Subblocks Blocks may contain blocks, for narrower scope: CREATE OR REPLACE PROCEDURE calc_totals IS year_total NUMBER; BEGIN year_total := 0; /* Nested anonymous block */ DECLARE month_total NUMBER; BEGIN month_total := year_total / 12; END; CREATE OR REPLACE PROCEDURE calc_totals IS year_total NUMBER; BEGIN year_total := 0; /* Nested anonymous block */ DECLARE month_total NUMBER; BEGIN month_total := year_total / 12; END;

40. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 40 Branching IF–THEN statements use THEN Must end with END IF Use ELSIF in place of ELSE IF Example:  http://pages.stern.nyu.edu/~mjohnson/dbms/eg/lec19/maxval.sql http://pages.stern.nyu.edu/~mjohnson/dbms/eg/lec19/maxval.sql IF THEN ELSIF END IF; IF THEN ELSIF END IF;

41. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 41 More ifs IF THEN ELSE END IF; IF THEN ELSE END IF; IF THEN ELSEIF ELSE END IF; IF THEN ELSEIF ELSE END IF;

42. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 42 Multiple elsifs An if statement can have multiple elseifs: IF salary >= 10000 AND salary <= 20000 THEN give_bonus(employee_id, 1500); ELSIF salary > 20000 AND salary <= 40000 THEN give_bonus(employee_id, 1000); ELSIF salary > 40000 THEN give_bonus(employee_id, 400); END IF; IF salary >= 10000 AND salary <= 20000 THEN give_bonus(employee_id, 1500); ELSIF salary > 20000 AND salary <= 40000 THEN give_bonus(employee_id, 1000); ELSIF salary > 40000 THEN give_bonus(employee_id, 400); END IF;

43. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 43 Nested ifs As usual, if statements can be nested: Can often be replaced with an ANDed condition IF condition1 THEN IF condition2 THEN statements2 ELSE IF condition3 THEN statements3 ELSIF condition4 THEN statements4 END IF; IF condition1 THEN IF condition2 THEN statements2 ELSE IF condition3 THEN statements3 ELSIF condition4 THEN statements4 END IF;

44. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 44 Case-statements Saw if and if-else statements last time Oracle 8i added support for case stmts Two kinds:  Simple cast stmt  “searched” case stmt Also: case expressions

45. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 45 Simple case statements General form: ELSE is optional expression and results are scalars  numbers, chars, strings, etc.; not tables  Literals or vars CASE expression WHEN result1 THEN statements1 WHEN result2 THEN statements2... ELSE statements_else END CASE; CASE expression WHEN result1 THEN statements1 WHEN result2 THEN statements2... ELSE statements_else END CASE;

46. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 46 Simple case e.g. CASE employee_type WHEN 'S' THEN award_salary_bonus(employee_id); WHEN 'H' THEN award_hourly_bonus(employee_id); WHEN 'C' THEN award_commissioned_bonus(employee_id); ELSE RAISE invalid_employee_type; END CASE; CASE employee_type WHEN 'S' THEN award_salary_bonus(employee_id); WHEN 'H' THEN award_hourly_bonus(employee_id); WHEN 'C' THEN award_commissioned_bonus(employee_id); ELSE RAISE invalid_employee_type; END CASE;

47. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 47 Simple case’s ELSE clause This ELSE is optional, but if omitted, you get an implicit else clause: Run example: Can use a NULL statement in the ELSE clause ELSE RAISE CASE_NOT_FOUND; ELSE RAISE CASE_NOT_FOUND; declare x number := 1; begin case x when 2 then dbms_output.put_line('2'); … declare x number := 1; begin case x when 2 then dbms_output.put_line('2'); …

48. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 48 CASE statements in SQL By the way: CASE statements are now supported in Oracle SQL itself SELECT CASE WHEN comm is null THEN 0 ELSE comm END FROM emp; SELECT CASE WHEN comm is null THEN 0 ELSE comm END FROM emp;

49. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 49 Loop example DECLARE i NUMBER := 1; BEGIN LOOP INSERT INTO T1VALUES(i,i); i := i+1; EXIT WHEN i>100; END LOOP; END; / DECLARE i NUMBER := 1; BEGIN LOOP INSERT INTO T1VALUES(i,i); i := i+1; EXIT WHEN i>100; END LOOP; END; /

50. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 50 More loops Infinite loop: while loop: LOOP executable_statements; END LOOP; LOOP executable_statements; END LOOP; WHILE condition LOOP executable_statements; END LOOP; WHILE condition LOOP executable_statements; END LOOP;

51. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 51 More loops Numerical for loop: Cursor for loop: FOR for_index IN low_value.. high_value LOOP executable_statements; END LOOP; FOR for_index IN low_value.. high_value LOOP executable_statements; END LOOP; FOR record_index IN my_cursor LOOP executable_statements; END LOOP; FOR record_index IN my_cursor LOOP executable_statements; END LOOP;

52. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 52 Word count program CREATE OR REPLACE FUNCTION wordcount (str IN VARCHAR2) RETURN PLS_INTEGER AS /* words PLS_INTEGER := 0; ***Commented out for intentional error*** */ len PLS_INTEGER := NVL(LENGTH(str),0); inside_a_word BOOLEAN; BEGIN FOR i IN 1..len + 1 LOOP IF ASCII(SUBSTR(str, i, 1)) len THEN IF inside_a_word THEN words := words + 1; inside_a_word := FALSE; END IF; ELSE inside_a_word := TRUE; END IF; END LOOP; RETURN words; END; CREATE OR REPLACE FUNCTION wordcount (str IN VARCHAR2) RETURN PLS_INTEGER AS /* words PLS_INTEGER := 0; ***Commented out for intentional error*** */ len PLS_INTEGER := NVL(LENGTH(str),0); inside_a_word BOOLEAN; BEGIN FOR i IN 1..len + 1 LOOP IF ASCII(SUBSTR(str, i, 1)) len THEN IF inside_a_word THEN words := words + 1; inside_a_word := FALSE; END IF; ELSE inside_a_word := TRUE; END IF; END LOOP; RETURN words; END; http://pages.stern.nyu.edu/~mjohnson/oracle/plsql/wordcount.sql

53. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 53 Explicit cursors v. for loop cursors DECLARE CURSOR occupancy_cur IS SELECT pet_id, room_number FROM occupancy WHERE occupied_dt = TRUNC (SYSDATE); occupancy_rec occupancy_cur%ROWTYPE; BEGIN OPEN occupancy_cur; LOOP FETCH occupancy_cur INTO occupancy_rec; EXIT WHEN occupancy_cur%NOTFOUND; update_bill (occupancy_rec.pet_id, occupancy_rec.room_number); END LOOP; CLOSE occupancy_cur; END; DECLARE CURSOR occupancy_cur IS SELECT pet_id, room_number FROM occupancy WHERE occupied_dt = TRUNC (SYSDATE); occupancy_rec occupancy_cur%ROWTYPE; BEGIN OPEN occupancy_cur; LOOP FETCH occupancy_cur INTO occupancy_rec; EXIT WHEN occupancy_cur%NOTFOUND; update_bill (occupancy_rec.pet_id, occupancy_rec.room_number); END LOOP; CLOSE occupancy_cur; END;

54. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 54 Explicit cursors v. for loop cursors DECLARE CURSOR occupancy_cur IS SELECT pet_id, room_number FROM occupancy WHERE occupied_dt = TRUNC (SYSDATE); BEGIN FOR occupancy_rec IN occupancy_cur LOOP update_bill (occupancy_rec.pet_id, occupancy_rec.room_number); END LOOP; END; DECLARE CURSOR occupancy_cur IS SELECT pet_id, room_number FROM occupancy WHERE occupied_dt = TRUNC (SYSDATE); BEGIN FOR occupancy_rec IN occupancy_cur LOOP update_bill (occupancy_rec.pet_id, occupancy_rec.room_number); END LOOP; END;

55. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 55 Using query results: SELECT … INTO create or replace function getprod(manuf varchar) return varchar as pn varchar(255); begin select prodname into pn from products where mfg = manuf; return pn; end; / create or replace function getprod(manuf varchar) return varchar as pn varchar(255); begin select prodname into pn from products where mfg = manuf; return pn; end; /

56. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 56 SELECT … INTO and exceptions create or replace function getprod(manuf varchar) return varchar as pn varchar(255); begin select prodname into pn from products where mfg = manuf; return pn; Exception When TOO_MANY_ROWS then dbms_output.put_line('got too many'); end; / create or replace function getprod(manuf varchar) return varchar as pn varchar(255); begin select prodname into pn from products where mfg = manuf; return pn; Exception When TOO_MANY_ROWS then dbms_output.put_line('got too many'); end; /

57. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 57 Programs and rights By default, only the creator of a program may run it (apart from the admin) If others should run, must GRANT them permission: Permissions can be revoked: Can also grant to particular roles or everyone: Wider/narrower grant ops are independent… SQL> GRANT EXECUTE ON wordcount TO george; SQL> REVOKE EXECUTE FROM wordcount TO george; SQL> GRANT EXECUTE ON wordcount TO dba_role; SQL> GRANT EXECUTE ON wordcount TO public; SQL> GRANT EXECUTE ON wordcount TO dba_role; SQL> GRANT EXECUTE ON wordcount TO public;

58. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 58 Packages Functions and procedures (and vars) can be grouped in packages  Like Java packages, C++ namespaces, etc. A pkg has a specification and a body  Somewhat like C++ class definitions Specification: declares public functions  “public” means: can be run by a user with EXECUTE authority on this pkg Body: defines all functions  Vars defined here are visible to the pkg’s programs

59. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 59 Package e.g. Run example: http://pages.stern.nyu.edu/~mjohnson/oracle/ plsql/numsys.sql http://pages.stern.nyu.edu/~mjohnson/oracle/ plsql/numsys.sql

60. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 60 Dynamic PL/SQL Saw “dynamic SQL” in the cases of Pro*C and JDBC  Ability to run ad-hoc (non-hard-coded) SQL in programs/scripts Can also do this in PL/SQL The string can be passed in, created from concatenation, etc. EXECUTE IMMEDIATE ;

61. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 61 Dynamic PL/SQL E.g.: write function to return number rows in an arbitrary table CREATE OR REPLACE FUNCTION rowCount ( tabname IN VARCHAR2) return integer as retval integer; begin execute immediate 'select count(*) from ' || tabname into retval; return retval; end; / CREATE OR REPLACE FUNCTION rowCount ( tabname IN VARCHAR2) return integer as retval integer; begin execute immediate 'select count(*) from ' || tabname into retval; return retval; end; /

62. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 62 Dynamic PL/SQL for DDL Ordinarily can’t do DDL in PL/SQL But you can in dynamic PL/SQL Here’s an e.g.: CREATE OR REPLACE procedure dropproc(procname in varchar2) as begin execute immediate 'drop procedure ' || procname; end; / CREATE OR REPLACE procedure dropproc(procname in varchar2) as begin execute immediate 'drop procedure ' || procname; end; /

63. Matthew P. Johnson, OCL4, CISDD CUNY, Sept 2005 63 Live examples Factorial function:  http://pages.stern.nyu.edu/~mjohnson/dbms/plsql/ fact.sql http://pages.stern.nyu.edu/~mjohnson/dbms/plsql/ fact.sql Converting between bases:  http://pages.stern.nyu.edu/~mjohnson/dbms/plsql/ numsys.sql http://pages.stern.nyu.edu/~mjohnson/dbms/plsql/ numsys.sql Directory of examples:  http://pages.stern.nyu.edu/~mjohnson/dbms/plsql/ http://pages.stern.nyu.edu/~mjohnson/dbms/plsql/