03/01/[email protected] databases

21/04/23 [email protected] 1

DATABASEShttp://nik.uni-obuda.hu/

szabozs/


USER AND RIGHTS MANAGEMENT

http://download-uk.oracle.com/docs/cd/B14117_01/server.101/b10759/statements_9013.htm


SYSTEM PRIVILEGES

• CREATE SESSION – REQUIRED TO LOG IN• CREATE TABLE• CREATE VIEW• CREATE PROCEDURE• CREATE USER• ALTER ANY TABLE• ALTER ANY TRIGGER• SELECT ANY TABLE• DROP ANY TABLE• DROP USER• ALL PRIVILEGES


ROLES, USERS

• CREATE USER {name} IDENTIFIED BY {password};

• DROP USER {name};

• Role ~ Group of privileges

• CREATE ROLE {name};

• DROP ROLE {name};


SETTING SYSTEM PRIVILEGES

• GRANT {privileges} TO {role/user};

• "WITH GRANT OPTION"

• GRANT {role} TO {user};

• REVOKE {privileges / role} FROM {user};


OBJECT-PRIVILEGES

• SELECT• INSERT• UPDATE• DELETE• ALTER• EXECUTE (for PL/SQL)• READ (for files)• REFERENCES (for constraints)• INDEX (for CREATE INDEX)


SETTING OBJECT-PRIVILEGES

• GRANT {privileges} ON {object} TO {user} [WITH GRANT OPTION];

• REVOKE {privileges / ALL} ON {object} FROM {user};


PL/SQL


PL/* INTRODUCTION


TRADITIONAL SQL

CLIENT SERVER

QUERY

RESPONSE-HEADER

ROWS

MODIFICATIONS


TRADITIONAL SQL PROCESSING

• Common tasks:– Special tasks that can not be done in SQL or

that are not SQL-specific tasks– Relatively simple processing of big amount of

data– Checks before update/insert/delete

• Even when using localhost, it is better to do these on the server


TRADITIONAL SQL PROCESSING

• Common tasks– More than one type of clients– Some function must be implemented It has

to be done separately for every language– Some common functions are not advised to

be implemented this way

• Even when using localhost, it is better to do these on the server


PL/*

• The server has two engines: the SQL engine and the PL/* engine: Procedural Language Engine

• It is usually a problem-oriented/procedural language, that allows us to do different programming tasks on the server

• Therefore, the server does some of the calculations/methods (usually those methods require a lot of data – high-load applications are not advised!)


PL/*

• Using PL/* programs, we can:– Execute simple, embedded script-code using

different structures– Create and use PROCEDURES for common

functions– Use special error handling: EXCEPTIONS– Create special procedures that are executed

automatically (e.g. to check something before insert/update/delete): TRIGGER


PL/*http://www.stanford.edu/dept/itss/docs/oracle/10g/appdev.101/b10807/01_oview.htm


PL/*

• Oracle uses a language that has an SQL-like syntax: PL/SQL

• PostgreSQL: PL/PGSQL, PL/PERL (2), PL/PYTHON, PL/TCL, PL/JAVA (2), PL/PHP, PL/R, PL/RUBY

• Embedded language vs. PL language


PL/SQL

• Probably the oldest and the most widely used Procedural Language

• A PL/PGSQL in PostgreSQL is similar, little differences GOOGLE


PL/SQL BLOCK• A separated area in the SQL*PLUS script-

program, that is interpreted by the PL/SQL engine

• Syntax:SET SERVEROUTPUT ON[DECLARE {variables}]BEGIN

{commands}[EXCEPTION

{exception handling}]END;/


VARIABLES• Client-side variables:

SET VERIFY ON;ACCEPT sal1 PROMPT 'Lower Bound?';ACCEPT sal2 PROMPT 'Higher Bound?';SELECT * FROM emp WHERE sal>&sal1 AND sal<&sal2; („SUBSTITUTE VARIABLES”)

• Server-side variables: DECLARE {name} {type}; RW in the PL/SQL, Nonexistant outside („LOCAL VARIABLES”)

VARIABLE {name} {type}; Usually RW in the PL/SQL, R outside („BIND VARIABLES”)


set verify off;set serveroutput on;ACCEPT var_I PROMPT 'WRITE

SOMETHING! ';VARIABLE var_II number;

DECLARE var_III number;BEGIN :var_II := &var_I; var_III := :var_II; DBMS_OUTPUT.PUT_LINE('block 1'); DBMS_OUTPUT.PUT_LINE(:var_II); DBMS_OUTPUT.PUT_LINE(var_III); DBMS_OUTPUT.PUT_LINE('ends');END;/PRINT var_II;

DECLARE var_III number;BEGIN var_III := :var_II; DBMS_OUTPUT.PUT_LINE('block 2'); DBMS_OUTPUT.PUT_LINE(:var_II); DBMS_OUTPUT.PUT_LINE(var_III); DBMS_OUTPUT.PUT_LINE('ends');END;/

BIND variables depend on the client as well!

BIND variables are used very often from external programs - parameterized queries

VARIABLES


VARIABLE TYPES

• Basic SQL types

• Reference types– {table}.{column}%TYPE;– {variable}%TYPE;– {table}%ROWTYPE; Record type ~ Pascal

• Record: varname.colname


ROWID

• Automatically generated unique ID for each row in a database

• "Secret column", like the rownum

• select emp.*, rowid, rownum from emp;

• Can be used to match the output rows in different output records


FUNCTIONS

• Traditional functions– UPPER(s), LOWER(s), MOD(x, n)– TO_CHAR(x[, s]), TO_DATE(d, s)

• Random number / text:– http://www.psoug.org/reference/dbms_random.html

– dbms_random.value(),dbms_random.value(2, 5)


PL/SQLSTRUCTURES


SELECTOrder of suffixes (PROCESSING)

1. FROM2. WHERE3. GROUP BY4. HAVING5. UNION/MINUS6. INTERSECT7. ORDER BY8. INTO

THE EXCEPTION!


SELECT Order of suffixes (when using them)

1. INTO2. FROM3. WHERE4. GROUP BY5. HAVING6. UNION/MINUS7. INTERSECT8. ORDER BY


SELECT INTO

• SELECT {field(s)} INTO {variable(s)} {other suffixes}

• The query must return with exactly one row!

• The query must return with exactly as many fields as many variables we list after the INTO

• Or: whole record %ROWTYPE


SELECT INTO

DECLARE var NUMBER;BEGIN SELECT empno INTO var FROM emp;END;/

• ORA-01422: exact fetch returns more than requested number of rows


SELECT INTODECLARE

var NUMBER;

var2 EMP%ROWTYPE;

BEGIN

SELECT empno INTO var FROM emp WHERE ename='KING';

SELECT * INTO var2 FROM emp WHERE ename='KING';

END;

/


IF

IF {condition} THEN{commands}

[ELSIF {condition} THEN{commands}]

[other ELSIF clauses][ELSE

{commands}]END IF;


LOOP

LOOP

{commands}

END LOOP;

To break the loop:

• EXIT;

• EXIT WHEN {condition};


WHILEWHILE {condition}{LOOP}

set serveroutput on;DECLARE

var NUMBER;BEGIN var:=0; WHILE var<=5 LOOP DBMS_OUTPUT.PUT_LINE(var); var:=var+1; END LOOP;END;/


FORFOR {variable} IN {lower} .. {higher}{LOOP}

set serveroutput on;DECLARE

var NUMBER;BEGIN FOR var IN 0 .. 5 LOOP DBMS_OUTPUT.PUT_LINE(var); END LOOP;END;/


FOR . . .

set serveroutput on;set verify on;accept A prompt 'Enter a number:'accept B prompt 'Another number:'DECLARE J NUMBER(5);BEGIN FOR j IN &A..&B LOOP DBMS_OUTPUT.PUT_LINE(j); END LOOP;END;/


SET VERIFY ON(default in sql-developer)

SQL> @x.sql

Enter a number:4

Another number:9

old 3: for j in &A..&B

new 3: for j in 4.9

FOR j IN &A .. &B


EXERCISES

• N!

• NM

• GCD (Greatest Common Divisor)

• LCM (Least Common Multiple)


N!ACCEPT num1 PROMPT 'First number (N)! ';

DECLARE res number;j number;

BEGIN res := 1; FOR j IN 1 .. &num1 LOOP res := res * j; END LOOP; DBMS_OUTPUT.PUT_LINE(res);END;/


NM

ACCEPT num1 PROMPT 'First number (N)! ';ACCEPT num2 PROMPT 'Second number (M)! ';

DECLARE res number;j number;

BEGIN res := 1; FOR j IN 1 .. &num2 LOOP res := res * &num1; END LOOP; DBMS_OUTPUT.PUT_LINE(res);END;/


GCDACCEPT num1 PROMPT 'First number (X)! ';ACCEPT num2 PROMPT 'Second number (Y)! ';

DECLAREX NUMBER;Y NUMBER;

BEGIN X:=&num1; Y:=&num2; WHILE X<>Y LOOP if (X<Y) THEN Y:=Y-X; END IF; if (X>Y) THEN X:=X-Y; END IF; END LOOP; DBMS_OUTPUT.PUT_LINE(X);END;/


LCMACCEPT num1 PROMPT 'First number (X)! ';ACCEPT num2 PROMPT 'Second number (Y)! ';-- LCM = (X*Y) / GCD(X,Y)DECLARE

X NUMBER;Y NUMBER;C NUMBER;

BEGIN X:=&num1; Y:=&num2; C:=X*Y; WHILE X<>Y LOOP if (X<Y) THEN Y:=Y-X; END IF; if (X>Y) THEN X:=X-Y; END IF; END LOOP; DBMS_OUTPUT.PUT_LINE('GCD : '||X); DBMS_OUTPUT.PUT_LINE('LCM : '||C/X);END;/


PL/SQL+ QUERIES


FOR – IMPLICIT CURSORset serveroutput on;DECLARE

someone emp%ROWTYPE;BEGIN FOR someone IN (SELECT * FROM emp) LOOP DBMS_OUTPUT.PUT_LINE('Name = ' ||

someone.ename); DBMS_OUTPUT.PUT_LINE('Salary = ' ||

someone.sal); END LOOP;END;/


DECLARING A CURSOR

DECLAREvar1 NUMBER(5);var2 EMP%ROWTYPE;CURSOR var2 IS

SELECT * FROM EMP;

The query is not executed, we only declare that the given variable will refer to the given query


USING CURSORS [FOR]ACCEPT low_sal PROMPT 'Lower bound! 'ACCEPT upp_sal PROMPT 'Upper bound! 'DECLARE CURSOR curs IS select * from emp; record EMP%ROWTYPE;BEGIN FOR record IN curs LOOP IF record.sal BETWEEN &low_sal AND &upp_sal THEN DBMS_OUTPUT.PUT_LINE(record.ename); END IF; END LOOP;END;


USING CURSORSDECLARE

OPEN

FETCH

CLOSE

EMPTY?

Yes

No


CURSOR ATTRIBUTES

• %FOUND – Successful FETCH?

• %NOTFOUND – Unsuccessful FETCH?

• %ROWCOUNT – Processed number of rows

• %ISOPEN – The cursor opened or not?


USING CURSORSACCEPT low_sal PROMPT 'Lower bound! 'ACCEPT upp_sal PROMPT 'Upper bound! 'DECLARE CURSOR curs IS select * from emp; record EMP%ROWTYPE;BEGIN

OPEN curs;LOOP

FETCH curs INTO record;EXIT WHEN curs%NOTFOUND;IF record.sal BETWEEN &low_sal AND &upp_sal THEN

DBMS_OUTPUT.PUT_LINE(record.ename); END IF;END LOOP;CLOSE curs;

END;


USING CURSORS FOR MODIFICATIONS

CREATE TABLE worker AS …

DECLARE

CURSOR curs IS SELECT * FROM workerFOR UPDATE [OF SAL] [NOWAIT];

record worker%ROWTYPE;

mysal worker.sal%TYPE;


BEGINOPEN cursor;LOOP

FETCH cursor INTO record;EXIT WHEN cursor%NOTFOUND;mysal := record.sal * 1.2;UPDATE worker set sal = mysal

WHERE CURRENT OF cursor; END LOOP;CLOSE cursor;

END;/

USING CURSORS FOR MODIFICATIONS


SEARCHING FOR PAIRS

• Aim: connect pair-records in a table using a calculation

• The searching process is done by a PL/SQL script program

• drop table worker;create table worker as select * from emp;

alter table worker add pair number(4);

update worker set pair=0;


PAIRS• Principle: Using cursorA, we loop through

the records and for each record, we loop again through the records using cursorB

• The calculation is done with the current records of cursorA and cursorB

• Problem: how to identify records that already have pairs?

ROWID CLOSE+OPEN


PAIRS

• Rowid: for every record, we use the ROWID or the primary key field to select the actual record from the table, thus we can check wether the pair field is set or not

• SELECT INTO, easier solution


PAIRS

SET SERVEROUTPUT ON

DECLARECURSOR curs_a IS select * from workers FOR UPDATE;CURSOR curs_b IS select * from workers FOR UPDATE;rec_a curs_a%ROWTYPE;rec_b curs_b%ROWTYPE;DIFF Numeric(5,2);


PAIRS

BEGINOPEN curs_a;LOOP

FETCH curs_a INTO rec_a;EXIT WHEN curs_a%NOTFOUND;IF rec_a.pair=0 THEN

[searching for a pair]END IF;

END LOOP;CLOSE curs_a;

END;/


PAIRSOPEN curs_b;LOOP

FETCH curs_b INTO rec_b;EXIT WHEN curs_b%NOTFOUND;IF (rec_a.sal>rec_b.sal) THEN

Diff:=(rec_a.sal-rec_b.sal)/rec_a.sal; ELSE

Diff:=(rec_b.sal-rec_a.sal)/rec_b.sal; END IF;

IF rec_b.pair=0 AND Diff<0.1 AND rec_a.empno<>rec_b.empno THEN

[setting the pair]END IF;

END LOOP;CLOSE curs_b;


PAIRSDBMS_OUTPUT.PUT_LINE(rec_a.ename ||

' ==> ' || rec_b.ename);UPDATE workers SET pair=rec_a.empno WHERE CURRENT OF curs_b;UPDATE workers SET pair=rec_b.empno WHERE CURRENT OF curs_a;******EXIT;

***** CLOSE curs_a; OPEN curs_a;


PAIRS

• Without Open+Close:

BLAKE ==> JONESJONES ==> FORDMARTIN ==> WARDALLEN ==> TURNERWARD ==> MILLERFORD ==> SCOTT

• With Open+Close:

BLAKE ==> JONESMARTIN ==> WARDALLEN ==> TURNERFORD ==> SCOTT


EXCEPTIONS


EXCEPTION HANDLING

• In other languages: we can mark parts of code for exception handling (try)

• Cause an exception ourselves (throw)

• We can do manual exception handling (catch, except)

• In PL/SQL, exception handling is more automatic: no TRY keyword

• But we can throw/catch!


PL/SQL BLOCK• A separated area in the SQL*PLUS script-

program, that is interpreted by the PL/SQL engine

• Syntax:SET SERVEROUTPUT ON[DECLARE {variables}]BEGIN

{commands}[EXCEPTION

{exception handling}]END;/


USER-DEFINED EXCEPTIONS

ACCEPT var PROMPT "Write something! ";DECLARE MyEx EXCEPTION;BEGIN IF &var=0 THEN RAISE MyEx; END IF; DBMS_output.put_line('Not zero.');EXCEPTION WHEN MyEx THEN DBMS_output.put_line('Zero!');END;/


AUTOMATIC EXCEPTIONS

When using SELECT INTO statement:– NO_DATA_FOUND– TOO_MANY_ROWS– OTHERS


AUTOMATIC EXCEPTIONSACCEPT job PROMPT "Type in a job! ";DECLARE emprec EMP%ROWTYPE;BEGIN SELECT * INTO emprec FROM emp WHERE job='&job'; dbms_output.put_line(emprec.ename);EXCEPTION WHEN No_Data_Found THEN DBMS_output.put_line('No

record!'); WHEN TOO_MANY_ROWS THEN DBMS_output.put_line('Too

much records!'); WHEN OTHERS THEN DBMS_output.put_line('Something

else!');END;/


STORED PROCEDURES


PROCEDURE

• Parameters:– {var.name} [{IN|OUT|IN OUT}] {type}– No size specification for types: VARCHAR2

• SHOW ERROR;(select * from user_errors)

• RAISE_APPLICATION_ERROR(err.code, message); [-20 999 .. -20 000]


PROCEDURE

CREATE OR REPLACE PROCEDURE WriteIt

IS

BEGIN

WriteLn('SzZs');

END;

/

select * from user_errors;


PROCEDURE

CREATE OR REPLACE PROCEDURE WriteLn (text VARCHAR2)

IS text2 VARCHAR2(50);BEGIN text2 := text; dbms_output.put_line(text2);END;/


PROCEDURE

ACCEPT some PROMPT "Write something ";

BEGIN

WriteIt;

WriteLn('&valami');

END;

/


EXECUTION / DELETION

• Execution outside a PL-SQL block:Execute WriteIt;Execute WriteLn('haha');

• Deletion: DROP PROCEDURE xxxxx;

• DROP PROCEDURE WriteLn;Execute WriteIt; Invalid object


FUNCTION

CREATE OR REPLACE FUNCTION {name}[ ({parameters}) ]

RETURN {type}IS

[{local variablees}]BEGIN

{commands}[EXCEPTION …]END;/


FUNCTIONCREATE OR REPLACE FUNCTION CountIt (num1 NUMBER,

num2 NUMBER)RETURN NUMBERIS c NUMBER(6); sum NUMBER(6);BEGIN sum := 0; FOR c IN num1 .. num2 LOOP sum := sum + c; END LOOP; RETURN sum;END;/


FUNCTION

ACCEPT first PROMPT "First num: ";ACCEPT second PROMPT "Second num: ";

BEGIN dbms_output.put_line(CountIt(&first, &second));END;/

DROP FUNCTION CountIt;


TRIGGERS


TRIGGER?

• trigger (n) = a piece (as a lever) connected with a catch or detent as a means of releasing it; esp: the part of the action moved by the finger to fire a gun

• to trigger (v) = to initiate, actuate, or set off by sg

"Event"


TRIGGER?

• In (Oracle) RDBMS: a stored procedure, that runs in connection with some event ("event handler")

• An event can be: DELETE, INSERT, UPDATE, CREATE, ALTER, DROP

• Important: BEFORE, AFTER, INSTEAD OF


TRIGGER

• Typical use: implementing a simple operation that can be integrated with the database Client-independent operations

• E.g. logging, consistency-checking, subquery-dependent checks


TRIGGER

CREATE OR REPLACE TRIGGER {name}[BEFORE | AFTER | INSTEAD OF]{event} [OR {event} …]ON {table}

[FOR EACH ROW [WHEN {condition}]][DECLARE {variables}]BEGIN

{commands}[EXCEPTION …]END;


TRIGGER

• If there is a RAISE_APPLICATION_ERROR() in the trigger's code, then the event that caused the trigger will not be executed (+ automatical ROLLBACK)

• FOR EACH ROW: the trigger is executed once for each row modified/deleted/inserted. Otherwise: once for every command


TRIGGER

• When using a row-level trigger, we have several automatically created variables:

• INSERT - :NEW

• DELETE - :OLD

• UPDATE - :NEW and :OLD


TRIGGER

CREATE OR REPLACE TRIGGER SomeTriggerBEFORE DELETE OR INSERT OR UPDATE ON empFOR EACH ROWBEGIN IF INSERTING THEN DBMS_OUTPUT.PUT_LINE(NEW: ' || :NEW.ename); ELSIF DELETING THEN DBMS_OUTPUT.PUT_LINE(DEL: ' || :OLD.ename); ELSIF UPDATING THEN DBMS_OUTPUT.PUT_LINE(MOD: ' || :OLD.ename || ' ==> '

|| :NEW.ename); END IF;END;/


TRIGGER

delete from emp where ename='KING';update emp set ename='SOME' where

ename='JAMES';insert into emp (empno, ename, mgr, deptno)

values (1, 'NEWMAN', NULL, 20);

DEL: KING1 row deleted.MOD: JAMES ==> SOME1 row updated.NEW: NEWMAN


TRIGGER

CREATE OR REPLACE TRIGGER SomeTrigger2BEFORE INSERT ON empFOR EACH ROWDECLARE

MINSAL NUMERIC(6,2);BEGIN SELECT MIN(SAL) INTO MINSAL FROM EMP; IF (:NEW.sal < MINSAL) THEN RAISE_APPLICATION_ERROR(-20000, 'TOO LOW

SALARY!'); END IF;END;/


TRIGGER

insert into emp (empno, ename, mgr, deptno, sal) values (4, 'NEWMAN2', NULL, 20, 5000);

insert into emp (empno, ename, mgr, deptno, sal) values (5, 'NEWMAN3', NULL, 20, 5);

delete from emp where empno < 100;


TRIGGERUJ: NEWMAN21 row created.insert into emp (empno, ename, mgr, deptno, sal)

values (5, 'NEWMAN3', NULL, 20, 5) *ERROR at line 1:ORA-20000: TOO LOW SALARY!ORA-06512: at "SCOTT.SOMETRIGGER2", line 6ORA-04088: error during execution of trigger

'SCOTT.SOMETRIGGER2'DEL: NEWMANDEL: NEWMAN22 rows deleted.


TABLE-LEVEL TRIGGERCREATE OR REPLACE TRIGGER SomeTrigger2BEFORE DELETE OR INSERT OR UPDATE ON empBEGIN IF INSERTING THEN DBMS_OUTPUT.PUT_LINE('NEW REC'); ELSIF DELETING THEN DBMS_OUTPUT.PUT_LINE('DELETED REC'); ELSIF UPDATING THEN DBMS_OUTPUT.PUT_LINE('MODDED REC'); END IF;END;/


THINGS TO REMEMBER…

• A table-level trigger will be executed once even if affected_rows=0!

• INSTEAD OF: row-level trigger (even without FOR EACH ROW!), used with views

• WHEN: we can define conditions for row-level triggers using the :NEW and the :OLD variables

• DROP TRIGGER xxxx;• ALTER TRIGGER xxxx ENABLE/DISABLE;


10.5


10.5

• Must forbid the insertion of workers who don't apply to some rules

• The condition-checks are done by separated functions!

• The trigger does nothing complicated: it calls the appropriate functions, and raises an exception if the record is considered bad


A TYPICAL TRIGGER

create or replace trigger Checks before insert on xxxxxxxxxxxfor each rowDECLARE

Ex1 Exception;Ex2 Exception;

BEGINif (F1(:NEW.field)<>1) then Raise Ex1; end if;if (F2(:NEW.field1, :NEW.field2)<>1) then Raise Ex2; end if;

EXCEPTIONWHEN Ex1 THEN Raise_Application_Error(-20500, 'Error1');WHEN Ex2 THEN Raise_Application_Error(-20501, 'Error2');WHEN OTHERS THEN Raise_Application_Error(-20999, 'Error');

END;/


Rules

create table dx as select * from emp;

1) The mgr field must point to an already existing boss

2) No boss can have more than two employees

3) The job must be an already existing job

4) The department must be an existing department


FUNCTION 1create or replace function Check_Boss(id int)return intIS

temp int;BEGIN

if id is null then return 0; end if;select distinct mgr into temp from emp where mgr=id;return 1;

EXCEPTIONWHEN NO_DATA_FOUND THEN return 0;WHEN OTHERS THEN return 0;

END;/select * from user_errors;


FUNCTION 1create or replace function Check_Boss(id int)return intIS

temp int;BEGIN

if id is null then return 0; end if;select count(*) into temp from emp where mgr=id;if temp>0 then

return 1;else

return 0;end if;

EXCEPTIONWHEN OTHERS THEN return 0;



THE TRIGGERcreate or replace trigger Checksbefore insert on dxfor each rowDECLARE

NonExistingBoss Exception;BEGIN

if (Check_Boss(:NEW.mgr)<>1) then Raise NonExistingBoss; end if;EXCEPTION

WHEN NonExistingBoss THEN Raise_Application_Error(-20500, ‘The boss does not exist!');WHEN OTHERS THEN Raise_Application_Error(-20999, ‘ERROR');

END;/

insert into dx (empno, sal, mgr, job, deptno) values (10, 500, 5, 'CLERK', 20);


FUNCTION 2create or replace function Check_Workers(id int)return intIS

temp int;BEGIN

select count(*) into temp from emp where mgr=id;if temp<2 then

return 1;else

return 0;end if;




FUNCTION 3create or replace function Check_Job(job_param varchar2)return intIS

temp int;BEGIN

select count(*) into temp from emp where job=job_param;if temp>0 then

return 1;else

return 0;end if;




FUNCTION 4create or replace function Check_Dept(dept_param int)return intIS

temp int;BEGIN

select count(*) into temp from dept where deptno=dept_param;if temp>0 then

return 1;else

return 0;end if;




DECLAREBad_Boss Exception;Bad_Workers Exception;Bad_Job Exception;Bad_Dept Exception;

BEGINif (Check_Boss(:NEW.mgr)<>1) then Raise Bad_Boss; end if;if (Check_Workers(:NEW.mgr)<>1) then Raise Bad_Workers; end if;if (Check_Job(:NEW.job)<>1) then Raise Bad_Job; end if;if (Check_Dept(:NEW.deptno)<>1) then Raise Bad_Dept; end if;

EXCEPTIONWHEN Bad_Boss THEN Raise_Application_Error(-20500, ‘Nonexistant boss');WHEN Bad_Workers THEN Raise_Application_Error(-20501, ‘Too many sub-employees!');WHEN Bad_Job THEN Raise_Application_Error(-20502, ‘Nonexistant job');WHEN Bad_Dept THEN Raise_Application_Error(-20503, ‘Nonexistant department');WHEN OTHERS THEN Raise_Application_Error(-20999, ‘Unknown error');

END;/


TESTING

• Nonexistant boss:– insert into dx (empno, sal, mgr, job, deptno) values

(10, 500, 5, 'CLERK', 20);• Too much sub-employees:

– insert into dx (empno, sal, mgr, job, deptno) values (10, 500, 7698, 'CLERK', 20);

• Nonexistant job:– insert into dx (empno, sal, mgr, job, deptno) values

(10, 500, 7788, 'PÉK', 20);• Nonexistant department:

– insert into dx (empno, sal, mgr, job, deptno) values (10, 500, 7788, 'CLERK', 70);


Rules

5) The salary must be lower than the average salary of the department

6) The salary must be higher than the minimum salary in the given job


This is the end…

• We add the functions to the trigger code

• We test the functionality of the trigger

03/01/[email protected] databases

Documents

privileges role

sql engine

drop role

special tasks

sql processingcommon

group of privilegescreate

obuda userscreate user

different programming