Why programming extensions? to program complex update transactions. where referential integrity is not addressed by data definition

Size: px

Start display at page:

Download "Why programming extensions? to program complex update transactions. where referential integrity is not addressed by data definition"

Luke Robertson
8 years ago
Views:

1 PL/SQL Why programming extensions? to program complex update transactions where referential integrity is not addressed by data definition enforcing particular integrity constraints, imposed by the nature of the application Stefan Stanczyk

integrity is not addressed by data definition enforcing

2 PL/SQL BLOCK declare DECLARATIONS variables procedures functions EXECUTABLE STATEMENTS SQL expressions PL/SQL expressions exception STATEMENTS HANDLING exceptions side effects ferrors / Stefan Stanczyk

expressions PL/SQL expressions exception STATEMENTS

3 COMMAND (.sql) FILE SQL expressions declare exception... / PL/SQL BLOCK SQL expressions Stefan Stanczyk

4 communication between PL/SQL block and pure SQL through variables declared within the block through auxiliary tables (i.e. tables that do not form part of the underlying database declaration of variables requires basic pre-defined data types: integer, real, char, date, boolean user-defined - types: records (include. nested records) & tables. Stefan Stanczyk

(i.e. tables that do not form part of the underlying database declaration of variables

5 declare x number; id STUDENT.STNO % TYPE; who STUDENT.NAME % TYPE;... select STNO, STNAME into id, who from STUDENT where...;... / Stefan Stanczyk

6 declare... lec-rec LECTURER % ROWTYPE... select ID, NAME DOB, ADDRESS, QUAL, POSITION into lec-rec from LECTURER where...;... / Stefan Stanczyk

7 declare type timet is record (minute integer, timet hour integer); type location is record (building char(2), location room integer); type tutorialt is record (day date, time timet, venue location, subject MODULE.TITLE% TYPE); seminar tutorialt;... seminar. day := 15-Feb-2000 ; seminar.time.minute := 15; seminar.time.hour := 9; day timet seminar.location.building := Newton ; seminar.location.room := 101 select TITLE into subject from MODULE where location subject Stefan Stanczyk

.. seminar. day := 15-Feb-2000 ; seminar.time.minute := 15; seminar.time.hour := 9; day timet seminar.location.

8 declare type marktabletype is table of REGISTER.RESULT% type index by binary_integer; type studenttabletype is table of REGISTER.STNO% type index by binary_integer; STUDENT-TAB studenttabletype; MARK-TAB marktabletype; i binary_integer := 0;... unbound one-dimensional array structure made of an unnamed column uniquely indexed by a pseudo-column of type binary integer for regcurrent in (select STNO, RESULT from REGISTER where CODE = 8049) loop i := i +1; STUDENT-TAB (i) := REGISTER.STNO; MARK-TAB (i) := REGISTER.RESULT; end loop; Stefan Stanczyk

.. unbound one-dimensional array structure made of an unnamed column uniquely indexed by a pseudo-column of type binary integer for

9 MESSAGE (PROMPT: varchar2(25), STNO: number(5))... select RESULT, STNO into X, id from REGISTER where CODE = 8049 and STNO = 40633;... if X >= 40 insert into MESSAGE values ( Module 8049 passed, id); elsif X >= 20 insert into MESSAGE values ( Re-examination granted on 8049, id); else insert into MESSAGE values ( Module 8049 failed, id); end if;... Stefan Stanczyk

.. if X >= 40 insert into MESSAGE values ( Module 8049 passed, id); elsif X >= 20 insert

10 declare cursor C is select STNO, RESULT from REGISTER where CODE = 8049 order by RESULT desc; ID integer; MARK real; open C; for i in loop fetch C into ID, MARK; exit when C%NOTFOUND; -- if < 5 students enrolled on 8049 insert into WHIZZ values ( ID, MARK); end loop; close C; / select * from WHIZZ; Stefan Stanczyk

. 5 loop fetch C into ID, MARK; exit when C%NOTFOUND; -- if < 5 students enrolled

11 declare... exception-name1 exception; exception-name2 exception; -- exception declaration exception -- exception handlers when <exception-name1> then executable statements; when< exception-name2> then executable statements;... when others then executable statements; Stefan Stanczyk

12 accept X prompt 'MODULE CODE: ' -- for an existing module accept Y prompt 'ASSESSMENT TITLE: ' -- insert new assignment accept Z prompt 'DESCRIPTION: ' declare ERR_MESSAGE char(100); ASGN char(15); MCODE integer; DUPL_ASSGN exception; INVALID_CODE exception; select CODE into MCODE from MODULE where CODE = '&&X; ASSESMENT-SCHEME MODULE ASSESSMENT DESCRIPTION 8049 Assignment 1 Normlisation 8049 Assignment 2 SQL program 8049 Examination 2-hour paper 8011 Examination 3-hour paper 8012 Assignment 1 Eiffel 8012 Assignment 2 C++ if MCODE = '&&X' then select ASSESSMENT into ASGN from ASSESSMENT-SCHEME where MODULE = '&&X' and DESCRIPTION = &&Z ; if ASGN = '&&Y' then raise DUPL_ASSGN end if; exception when NO_DATA_FOUND then insert into RUNINFO values (sysdate, 'Invalid module code'); end if; exception when NO_DATA_FOUND then insert into RUNINFO values (sysdate, 'Invalid module code'); when DUPL_ASSGN then insert into RUNINFO values (sysdate, 'Assignment already exists'); when others then ERR_MESSAGE = substr(sqlerrm,1,100); insert into RUNINFO values (sysdate, ERR_MESSAGE); commit; / Stefan Stanczyk

Assignment 2 SQL program 8049 Examination 2-hour paper 8011 Examination 3-hour paper 8012 Assignment 1 Eiffel 8012 Assignment 2 C++ if MCODE = '&&X' then select ASSESSMENT into ASGN from

13 procedure upgrade (student_id integer, module_id integer, amount real) is old_mark real; new_mark real; out_of_range exception; select RESULT into old_mark from REGISTER where STNO = student_id and CODE = module_id; new_mark := old_mark + amount; if new_mark > 99 then raise out_of_range else update ACCOUNT set RESULT = new_mark where STNO = student_id and CODE = module_id; end if; exception when out_of_range then.. end upgrade; upgrade (who, on_what, by_how_much) Stefan Stanczyk

amount; if new_mark > 99 then raise out_of_range else update ACCOUNT set RESULT = new_mark where STNO = student_id and

14 create trigger <trigger name> before insert or update of <specification of table attributes> for each row when <boolean expression> -- conditions activating the trigger declare types, variables, exceptions PL/SQL expression... exception handlers... Stefan Stanczyk

activating the trigger declare... -- types, variables, exceptions.

When an exception occur a message which explains its cause is received. PL/SQL Exception message consists of three parts.

When an exception occur a message which explains its cause is received. PL/SQL Exception message consists of three parts. ERROR HANDLING IN PLSQL When an SQL statement fails, the Oracle engine recognizes this as an Exception Condition. What is Exception Handling? PLSQL provides a feature to handle the Exceptions which occur