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ORACLE SQL. Overview. Personal DBMS Vs Client/Server DBMS Oracle 8 Environment SQL – syntax and examples PL/SQL-introduction. Server Gets file requests from clients Sends files to client Receives files back from clients. Personal DBMS. NETWORK. Client B Sends file requests to server
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Overview • Personal DBMS Vs Client/Server DBMS • Oracle 8 Environment • SQL – syntax and examples • PL/SQL-introduction
Server Gets file requests from clients Sends files to client Receives files back from clients Personal DBMS NETWORK Client B Sends file requests to server Receives files from server Updates data Sends files back to server Client A Sends file requests to server Receives files from server Updates data Sends files back to server
Personal DBMS - Problems • Demand on the client and the network • Does not perform table locking automatically • Not fault tolerant in the case of client failure • Do not have file based transaction logging
Server Gets data requests from clients Adds, Deletes and updates data Sends results to clients Client/server DBMS NETWORK Client B Sends data requests to server Receives results from server Sends new data or changes to server Client A Sends data requests to server Receives results from server Sends new data or changes to server
Client/Server DBMS • Minimal load on the client and the network • Performs table locking automatically • Fault tolerant in the case of client failure • File based transaction logging
Oracle 8 Environment • SQL * Plus • PL/SQL • Query Builder • Developer • Enterprise Manager • Web application server
SQL*Plus commands Sqlplus username/password ALTER USER user-name IDENTIFIED BY newpassword START filename | @ filename CLEAR SCREEN HELP <command> SAVE filename[.ext] REPLACE|APPEND EXIT
SQL • Both an ANSI and ISO standard • Types of commands: • Data Definition Language (DDL) : Create, Alter, Drop, Rename, Truncate • Data Manipulation Language (DML): Insert, Delete, Update • Data Retrieval: Select • Transaction Control: Commit, Rollback, Savepoint • Data Control Language (DCL): Grant, Revoke
DEPARTMENT POSITION QUALIFICATION
Data Definition Language: CREATE TABLE {table} ( {column datatype [DEFAULT expr] [column_constraint] ... | table_constraint} [, { column datatype [DEFAULT expr] [column_constraint] ... ) ALTER TABLE {table} [ADD|MODIFY {column datatype [DEFAULT expr] [column_constraint]} [DROP drop_clause] DROP TABLE {table} [cascade constraints] DESC {table}
CREATE TABLE Emp ( empid Decimal(10) NOT NULL, positionid Number(2), supervisorid Number(3), deptid Number(2), qualid Number(1), lname varchar2(10), fname varchar2(10), salary Decimal(10,2), hiredate Date, commission Decimal(4,2), PRIMARY KEY (empid), FOREIGN KEY (positionid) REFERENCES Position(positionid), FOREIGN KEY (deptid) REFERENCES Dept(deptid), FOREIGN KEY (qualid) REFERENCES Qualification(qualid) ); ALTER TABLE EMP MODIFY Commission decimal(7,2);
Data Manipulation Language: INSERT INTO {table | view} [ (column [, column] ...) ] VALUES (expr,expr ...) UPDATE {table | view } SET { (column [, column] = { expr | } [WHERE condition] DELETE [FROM] {table | view} [WHERE condition]
INSERT INTO Dept( deptid,deptname,location) VALUES(50,'IT','Dallas'); INSERT INTO Emp(empid, lname,fname,positionid, supervisorid,hiredate, salary,deptid,qualid) VALUES(227,'howser','Barbara',4,111,'25-AUG-83',45000,10,3); UPDATE dept SET deptname='Sales' WHERE deptID=50; DELETE FROM dept WHERE deptid='50';
Data Retrieval: SELECT [DISTINCT | ALL] {table|view} FROM {table | view} [WHERE condition ] [GROUP BY expr [, expr]] [ORDER BY {expr} [ASC | DESC]] select * from dept; select deptname from dept where deptid='10'; select lname,fname from emp order by lname desc; select max(salary) from emp group by positionid; select deptname from dept,emp where dept.deptid=emp.deptid and emp.empid='111';
Transaction Control: COMMIT ROLLBACK [ to {savepoint}] SAVEPOINT {name} commit; savepoint point1; rollback to point1;
Data Control Language: GRANT [privileges] ON object TO user|public [WITH GRANT OPTION] REVOKE [privileges] ON object TO user|public [CASCADE CONSTRAINTS] grant select,update on emp to XYZ ; revoke update on emp to XYZ;
A PL/SQL Example: CREATE OR REPLACE PROCEDURE raise_salary (empno INTEGER, increase REAL) IS current_salary REAL; salary_missing EXCEPTION; BEGIN SELECT salary INTO current_salary FROM emp WHERE emp.empid = empno; IF current_salary IS NULL THEN RAISE salary_missing; ELSE UPDATE emp SET salary = salary + increase WHERE emp.empid = empno; END IF; EXCEPTION WHEN salary_missing THEN UPDATE emp SET salary=0 where emp.empid=empno; END raise_salary;