Stored procedure, stored function (Oracle)

Stored Procedures and Stored Functions

Refers to the subprograms called stored procedures and stored functions.

What is the difference between stored procedure and stored function?

Stored function: The function value can be returned through the return statement.

Stored procedure: no

Other than that we can consider them to be exactly the same.

stored procedure

Create stored procedure

Use the create procedure command to resume stored procedures.

grammar:

create [or replace] procedure procedure name (parameter list)

PLSQL subroutine body;

print hello word

--print hello world
create or replace procedure sayhelloworld
as
  --Description section
begin
  dbms_output.put_line('hello world');
end;
/

After compilation:

Call the stored procedure method:

1. exec process name

2、begin

procedure name;

end;

Test calling stored procedure

--Connect to the database

C:\WINDOWS\system32>sqlplus scott/ [email protected] :1521/orcl

SQL>--call method one

SQL> set serveroutput on

SQL> exec sayhelloworld;

hello world

PL/SQL procedure completed successfully.

SQL> -- call method two:

SQL> begin

2 sayhelloworld();

3 sayhelloworld();

4 end;

5 /

hello world

PL/SQL procedure completed successfully.

Stored procedure with parameters

--Increase the salary of designated employees by 100, and print the salary before and after the increase
create or replace procedure raiseSalary(eno in number) --in is the input parameter
as
  --Description section
  psal emp.sal%type;

begin
  -- Get the salary before the increase
  select sal into psal from emp where empno=eno;

  update emp set sal=sal+100 where empno=eno;

  --Do you want to commit?
  --In order to ensure that in the same transaction, whoever calls commit commits
  dbms_output.put_line('Before rising: '||psal||' After rising: '||(psal+100));
end;
/

test:

stored function

A function is a named stored procedure that takes parameters and returns a computed value. Functions and procedures are similar in structure, but must have a return clause that returns the function value. The function specification specifies the function name, the type of the result value, and the parameter type.

Stored function syntax:

create[or replace] function function name (parameter list)

return function value type

PLSQL subroutine body;

Query employee's annual income

-- Query the annual income of an employee
create or replace function queryempincome(eno in number)
return number
as
  --Monthly salary and bonus
  psal   emp.sal%type;
  pcomm  emp.comm%type;
begin
  select sal,comm into psal,pcomm from emp where empno=eno;
  -- return annual income
  return psal*12+nvl(pcomm,0);
end;
/

test

in and out in procedures and functions

In general, the difference between a procedure and a function is that a function can have a return value; a procedure has no return value.

But both procedures and functions can specify one or more output parameters through out, and we can use out parameters to return multiple values in procedures and functions.

When to use stored procedure/stored function?

Principle (not required):

If there is only one return value, use a stored function; otherwise, use a stored procedure.

stored procedure

create or replace procedure queryEmpInfo(eno in number,
                                         pname out varchar2,
                                         psal  out number,
                                         pjob  out varchar2)
as
begin
  select ename,sal,empjob into pname,psal,pjob from emp where empno=eno;
end;

Stored procedure, stored function (Oracle)

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