RDBMS Using Oracle. Use of IN OUT

Transcription

1 RDBMS Using Oracle PL/SQL Procedural Language/Structural Query Language PL/SQL Procedures Use of IN OUT Example: Format phone Procedure 1

2 Example: Format phone Procedure Input Output (300) Format phone Procedure create OR REPLACE PROCEDURE FORMAT_PHONE (v_phone_no in out varchar2) is begin v_phone_no := '(' substr(v_phone_no,1,3) ')' substr(v_phone_no,4,3) '-' substr(v_phone_no,7); DBMS_OUTPUT.put_line(v_phone_no); END;? Procedure created. 2

3 Declaring variable Format phone Procedure contd SQL> VARIABLE g_phone_no varchar2(15); Assigning value to variable SQL> begin :g_phone_no := ; End; Execute Procedure? SQL> execute FORMAT_PHONE(:g_phone_no); PL/SQL procedure successfully completed.? SQL> PRINT G_PHONE_NO; G_PHONE_NO (300) Output (300) Example 2 (SHOW SUMMARY) SQL> create OR REPLACE PROCEDURE show_summary (v_deptno in number) is v_count number; v_avg number; v_sum number; v_min number; v_max number; begin select count(empno), avg(sal), sum(sal), min(sal), max(sal) into v_count, v_avg, v_sum, v_min, v_max from emp where deptno = v_deptno; DBMS_OUTPUT.put_line(concat('Total # of employees = ', v_count)); DBMS_OUTPUT.put_line(concat('Salary Average = ', v_avg)); DBMS_OUTPUT.put_line(concat('Salary Total = ', v_sum)); DBMS_OUTPUT.put_line(concat('Maximum Salary = ',v_max)); DBMS_OUTPUT.put_line(concat('Minimum Salary = ', v_min)); END; 3

4 Procedure Execution/OUTPUT SQL> execute show_summary(10); Total Number of employees are = 3 Salary Average = Salary Total = 8750 Maximum Salary = 5000 Minimum Salary = 1300? PL/SQL procedure successfully completed. Methods for passing Parameters 1. Positional 2. Named 3. Combination 4

5 Methods for passing Parameters? Positional List values in the order in which the parameters are declared.? Named List values in arbitrary order, using parameter name.? Combination We can also use combination of both above. Example create or replace procedure add_emp (v_empno in emp.empno%type, v_deptno in emp.deptno%type, v_ename in emp.empno%type DEFAULT UNKNOWN ) is begin insert into emp(empno,deptno,ename) values(v_empno, v_deptno, v_ename); end;? Procedure created. Note:- Similarly Practice procedures For UPDATE & DELETE 5

6 Methods for passing Parameters? Positional SQL> add_emp (1234, 10, TOM );? Named SQL> add_emp (v_derpno => 10, v_empno =>1234, v_ename = > TOM); SQL> add_emp (v_derpno => 10, v_empno =>1234)? Combination SQL> add_emp (1234, v_derpno => 10 ); Invoking a procedure from a Anonymous PL/SQL Block Declare V_id number := 7900; Begin procedure_name (v_id) Commit; End; We can also assign value to a variable like this. Procedure Call Inside procedure 6

7 Drop Procedure? Syntax SQL> Drop procedure <procedure_name>; SQL/PLSQL Tips? search PL/SQL code SELECT * FROM USER_SOURCE? To retrieve the version information for Oracle, you execute the following SQL statement: select * from v$version where banner like 'Oracle%'; 7

8 Select the Nth highest value from a table select level, max('col_name') from my_table where level = '&n' connect by prior ('col_name') > 'col_name ') group by level; Example SQL> select level, max(sal) from emp where level = '&n' connect by prior (sal) > sal group by level Learn If-Else What is the result of comparing NULL with NULL? Declare a number := NULL; b number := NULL; Begin if a=b then dbms_output.put_line('true, NULL = NULL'); elsif a<>b then dbms_output.put_line('false, NULL <> NULL'); else dbms_output.put_line('undefined NULL is neither = nor <> to end if; end; NULL is neither equal to NULL, nor it is not equal to NULL. Any comparison to NULL is evaluated to NULL. Look at this code example to convince yourself. NULL'); 8

9 ? You can grant users various privileges to tables. These privileges can be any combination of select, insert, update, delete, references, alter, and index. Below is an explanation of what each privilege means. Privilege Description Select Ability to query the table with a select statement. Insert Ability to add new rows to the table with the insert statement. Update Ability to update rows in the table with the update statement. Delete Ability to delete rows from the table with the delete statement. References Ability to create a constraint that refers to the table. Alter Ability to change the table definition with the alter table statement.? The syntax for granting privileges on a table is: Grant privileges on object to user? For example, if you wanted to grant select, insert, update, and delete privileges on a table called suppliers to a user name smithj, you would execute the following statement: GRANT SELECT, INSERT, UPDATE, DELETE ON SUPPLIERS TO SMITH;? You can also use the all keyword to indicate that you wish all permissions to be granted. For example: GRANT ALL ON SUPPLIERS TO SMITH; REVOKE ALL ON SUPPLIERS TO SMITH; (To Revoke Privilege)? If you wanted to grant select access on your table to all users, you could grant the privileges to the public keyword. For example: GRANT SELECT ON SUPPLIERS TO PUBLIC; 9

10 How can I protect my PL/SQL source code?? PL/SQL V2.2, available with Oracle7.2, implements a binary wrapper for PL/SQL programs to protect the source code. This is done via a standalone utility that transforms the PL/SQL source code into portable binary object code (somewhat larger than the original). This way you can distribute software without having to worry about exposing your proprietary algorithms and methods. SQL*Plus and SQL*DBA will still understand and know how to execute such scripts. Just be careful, there is no "decode" command available.? The syntax is:? wrap iname=myscript.sqlmyscript.sql oname=xxxx.plb Can one call DDL statements from PL/SQL?? One can call DDL statements like CREATE, DROP, TRUNCATE, etc. from PL/SQL by using the "EXECUTE IMMEDATE" statement. Users running Oracle versions below 8i can look at the DBMS_SQL package (see FAQ about Dynamic SQL). Begin EXECUTE IMMEDIATE 'CREATE TABLE X(A DATE)'; end; NOTE: The DDL statement in quotes should not be terminated with a semicolon. 10

11 Thanks 11