PL/SQL
Cursors :(SQL statement in PL/SQL block)
Implicit cursors :
created or started by Oracle
4 steps
create
open
fetch the data
close
4 attributes :
SQL%FOUND
SQL%NOTFOUND
SQL%ROWCOUNT
SQL%ISOPEN
Explicit cursors : normally for more than one row/records
we will give the name(C1) of cursor
C1%FOUND
C1%NOTFOUND
C1%ROWCOUNT
C1%ISOPEN
eg : create a cursor to store all the col/rows from emp table
1. create the cursor
cursor C1 is select * from emp;
2. open the cursor
open C1;
3. fetch the data from the cursor into a variable
abc emp%rowtype;(all columns)
abc1 C1%rowtype;(some solumns)
fetch C1 into abc;
all the records (loop)
loop
fetch C1 into abc;
exit when C1%NOTFOUND;
end loop
4.close or stop the cursor
close C1;
eg :
declare
cursor C2 is select ename, empno from emp;
a1 C2%rowtype;
begin
open C2;
fetch C2 into a1;
loop
DBMS_OUTPUT.put_line(a1.ename);
exit when C2%NOTFOUND;
end loop;
close C2;
end;
Stored Procedure & Functions
Function : always return something
eg : SUM(), AVG(), SUBSTRING(), LENGTH();
Procedure : may or may not return something
eg : commit, rollback, savepoint;
run a PL/SQL block
parameter : arguments
eg :
cursor C1(emp_no number)
a1 IN number, a2 OUT number, a3 IN OUT number
IN : readonly (pass value inside the function, cannot change the value)
eg : constant variable
OUT : write only (cannot pass the value, from inside the function or procedure, get the data or value outside, can change the data)
IN OUT : read and write
a procedure can be thought of a PL/SQL or SQL command, like commit.
create a stored procedure
CREATE [OR REPLACE] PROCEDURE proc_name [(argument[IN|OUT|INOUT] type [DEFAULT value]
...
argument [IN|OUT|IN OUT] type]
IS|AS
<declarative section>
begin
<procedure body>
[EXCEPTION
<exception handlre>]
end;
note : always use CREATE OR REPLACE
actual & formal parameters
exception section
procedure body
eg :
create or replace procedure p1
(a1 IN number, a2 OUT varchar2, a3 IN OUT varchar2)
IS
--> create variables
--> cursor
begin
--> SQL commands
exception
when
end;
/
note : not give the size of the type.
run or execute : (in 1.SQL*PLUS or in 2.PL/SQL block)
1.
exec p1(10, ABC, 'DDD');
2.
begin
var1 := p1(2, aa, 'AAA');
end;
eg :
create or replace procedure EmpInfo(p_empno IN emp.empno%type, p_ename OUR emp.ename%type, p_job OUT emp.job%type, p_deptno OUT emp.deptno%type)
is
cursor emp_info_cur(p_empno emp.empno5type)
is
select ename, job, deptno from emp where empno = p_empno;
r_emp_info emp_info_cur%rowtype;
begin
open emp_info_cur(p_empno);
fetch emp_into_cur into r_emp_info;
close emp_info_cur;
p_ename := r_emp_info.ename;
p_job := r_emp_info.job;
p_deptno := r_emp_info.deptno;
end;
create a stored function
CREATE [OR REPLACE] FUNCTION func_name [(argument [IN|OUT|IN OUT] type [DEFAULT value]
...
argument [IN|OUT|IN OUT] type]
RETURN return_type
IS|AS
<declarative section>
BEGIN
<function body>
[EXCEPTION
<exception handlers>]
END;
note : the function body should include at least one RETURN statement, RETURN expression;)
eg :
create or replace function f1
(a1 IN number, a2 OUT varchar2, a3 OUT number)
return number
is
num1 number;
begin
num1 := 10;
return num1;
exception
when NO_DATA_FOUND then
end;
method to execute the function :
1. variable_name := function_name;
2. select function_name from dual;
3. DBMS_OUTPUT.put_line(Function_name);
1 & 3 --> PL/SQL block
2 --> SQL*PLUS
eg :
select SUM(1,2) from dual;
eg :
1. display the salary from the emp table for the empname. --> give a fixed name or user input.
create or replace function f1(emp_name IN varchar2)
return number
is
a emp.sal%type;
begin
select sal into a from emp
where ename='FORD';
return a;
end;
how to run or execute the function :
select f1('FORD') from dual;
OR
declare
b number;
begin
b := f1('KING');
DBMS_OUTPUT.put_line(b);
end;
2. input the name & display the job.
create or display function f2(emp_job IN varchar2)
return varchar
is
job emp.job%type;
begin
select job into job from emp
where ename = '&name';
return job;
end;
3. input name & display job and salary.
create or replace function f3(emp_name IN varchar2, emp_job OUT varchar2)
return number
is
f_sal emp.sal%type;
begin
select job, sal into f_job, sal from emp where ename = name;
return f_sal;
end;
execute the function :
declare
f_sal number;
f_job varchar2;
begin
f_sal := f2('FORD', f_job);
DBMS_OUTPUT.put_line(f_sal || ' ' || f_job);
end;
4. display empno, name, sal, job & input empno.
display OUT as RETURN, input IN
create or replace function f4
(empno1 IN emp.empno%type,
salary OUT emp.sal%type, job1 OUT emp.job%type)
return varchar2
is
name emp.ename%type;
begin
select ename, job, sal
into name, job1, salary
from emp where empno = empno1;
return name;
EXCEPTION
when NO_DATA_FOUND then
DBMS_OUTPUT.put_line('NO EMPLOYEE');
end;
execute the function :
declare
empno12 emp.empno%type := &empno12;
ename1 emp.ename%typt;
job12 emp.job%type;
salary1 emp.sal%type;
begin
ename1 := f4(empno12, salary1, job12);
DBMS_OUTPUT.put_line(empno12 || ' ' || ename1 || ' ' || salary1 || ' ' || job12);
end;
drop function function_name;
user_objects : all your functions, procedures, packages, triggers
5. default value
select f1(7333) from dua;
select f1 from dual;
eg :
create or replace function f5(n number default 1234)
return number
is
salary emp.sal%type;
begin
select sal into salary from emp where empno = n;
return salary;
end;
select f5(7354) from dual;
select f5 from dual;
