Writing powerful stored procedures in PL/SQL

MARIADB
Writing powerful stored
procedures in PL/SQL
Alton Dinsmore
Senior Solution Architect
MariaDB Corporation

Agenda
● Introduction to PL/SQL
○ History and Origin of PL/SQL
○ What is PL/SQL
■ Why Use PL/SQL
○ Evolution of PL/SQL
● MariaDB PL/SQL
○ Why Add PL/SQL to MariaDB
■ Migrations
■ Knowledge of PL/SQL
■ Missing Functions and UDF
○ Creating a Stored Procedure or Function

Agenda
● Advanced PL/SQL Procedures
○ Cursors, LOOP, Variables, Exceptions, and more
○ Packages
● Real World Experiences
○ Where PL/SQL can be problematic
○ PL/SQL and Database Load
● Q&A

History and Origins of PL/SQL
How did we get here???
● Hierarchical/CODASYL Databases - DL/1, IMS, Total, IDMS
● Inverted List Databases - ADABASE, Model 204, Datacom/DB
○ B-Tree, Hashed, Bit Mapped Indexes
○ 4GL - Natural, User Language, Ideal
● IBM System R Research Project - 1974
● SQL/DS, DB2, Ingres, Informix, Oracle, Sybase
● Each RDBMS release unique Stored Procedure Language
● PL/SQL was released with Oracle V6.0 in July 1988
● Modeled after ADA and Pascal
● Oracle (Relational Software) first contract was with US Government

What is PL/SQL
● PL/SQL is Procedural Language for SQL
● Code for PL/SQL and resides in the Database
● Code is executed in the Database
● Code is normally executed dynamically and it makes calls to internal c routines
● Block Structured
● Easy to Learn Powerful
● Database Triggers Language
● Data never leaves the Database server except for results

Evolution of PL/SQL
● PL/SQL first release was very limited
○ No Stored Procedures
○ Weak Exception Handling
○ Virtually no Error Handling
● Now the foundation of many Oracle developed applications

Why add PL/SQL to MariaDB
● MariaDB already had an excellent Procedural Language
● Migrations from Oracle to MariaDB
○ Cost Reduction
○ Time Reduction
○ Leverage Skill Sets
● Is It 100% the same - NO
○ Most Major structures are supported
○ Some Functions are Different
○ Easy to extend MariaDB using UDF (User Defined Functions)
Please attend Migration Presentation for more Information

Using PL/SQL in MariaDB
SET SQL_MODE=ORACLE;
Verify by:
SELECT @@SQL_MODE;
|PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,ORACLE,NO_KE
Y_OPTIONS,NO_TABLE_OPTIONS,NO_FIELD_OPTIONS,NO_AUTO_C
REATE_USER,SIMULTANEOUS_ASSIGNMENT |
SET SQL_MODE=@@GLOBAL.SQL_MODE;

Let’s create a PL/SQL
Stored Procedure !

Creating a PL/SQL Stored Procedure in MariaDB
DELIMITER //
BEGIN
Select 'Hello World';
END;
//
DELIMITER ;

Creating a PL/SQL Function in MariaDB
DELIMITER //
CREATE OR REPLACE FUNCTION hello RETURN VARCHAR2 DETERMINISTIC
AS
BEGIN
DECLARE
vString VARCHAR2(255) := NULL;
BEGIN
SELECT 'Hello world from MariaDB PL/SQL Function!' INTO vString FROM dual;
RETURN vString;
END;
END hello;
//

Now let’s call the PL/SQL
Function?

Calling a PL/SQL Function in MariaDB
DECLARE
vString VARCHAR(255) := NULL;
BEGIN
vString := hello();
SELECT vString;
END;
//
DELIMITER ;

Creating a PL/SQL Trigger in MariaDB
CREATE TRIGGER tr1 BEFORE INSERT ON t1
FOR EACH ROW
DECLARE
cnt INT := 0;
BEGIN
IF :NEW.a IS NULL THEN cnt:=cnt+1; END IF;
IF :NEW.b IS NULL THEN cnt:=cnt+1; END IF;
IF :NEW.c IS NULL THEN :NEW.c:=cnt; END IF;
END;
//

Cursor, Loop, and
Variables in a PL/SQL
Procedure!!!!

Cursors, Loops, and Variables
CREATE or REPLACE PROCEDURE t1demo() as
id int; ** Local Variable Integer
CURSOR c1 IS ** Cursor
SELECT a FROM t1; ** Select can be used instead of
DBMS_OUTPUT
BEGIN
OPEN c1;
LOOP ** Loop thru the records
one at a time
FETCH c1 INTO id;
SELECT id;
END LOOP;
CLOSE c1;

Is there Default
Exceptions???

Exceptions - Predefined
BEGIN
...
EXCEPTION
WHEN TOO_MANY_ROWS THEN ...
WHEN NO_DATA_FOUND THEN ...
WHEN OTHERS THEN NULL;
END;

What about User Defined
Exceptions???

Exceptions - User Defined
CREATE FUNCTION f1 (a INT) RETURN INT
AS
e1 EXCEPTION;
BEGIN
IF a < 0 THEN
RAISE e1;
END IF;
RETURN 0;
EXCEPTION
WHEN e1 THEN RETURN 1;
END;

Packages
● Schema object that groups logically related
○ PL/SQL data types,
○ items (e.g. variables, cursors, exceptions)
○ and subprograms.
● Packages usually have two parts:
○ a specification
○ a body
● Sometimes the body is unnecessary.

Packages
CREATE OR REPLACE PACKAGE employee_tools AS
FUNCTION getSalary(eid INT) RETURN DECIMAL(10,2);
PROCEDURE raiseSalary(eid INT, amount DECIMAL(10,2));
PROCEDURE raiseSalaryStd(eid INT);
PROCEDURE hire(ename TEXT, esalary DECIMAL(10,2));
END;

Now for some of the
Package Body!!!!!!

Packages
CREATE PACKAGE BODY employee_tools AS
-- package body variables
stdRaiseAmount DECIMAL(10,2):=500;
-- private routines
PROCEDURE log (eid INT, ecmnt TEXT) AS
BEGIN
INSERT INTO employee_log (id, cmnt) VALUES (eid,
ecmnt);
END;

Packages
-- public routines
PROCEDURE hire(ename TEXT, esalary DECIMAL(10,2)) AS
eid INT;
BEGIN
INSERT INTO employee (name, salary) VALUES (ename,
esalary);
eid:= last_insert_id();
log(eid, 'hire ' || ename);
END;

Packages
FUNCTION getSalary(eid INT) RETURN DECIMAL(10,2) AS
nSalary DECIMAL(10,2);
BEGIN
SELECT salary INTO nSalary FROM employee WHERE
id=eid;
log(eid, 'getSalary id=' || eid || ' salary=' ||
nSalary);
RETURN nSalary;
END;

What about Oracle’s
Default Packages!!!!!!

Default Oracle Packages
DELIMITER //
CREATE OR REPLACE PACKAGE DBMS_OUTPUT AS
PROCEDURE PUT_LINE(pString IN VARCHAR2);
END DBMS_OUTPUT;
//

CREATE OR REPLACE PACKAGE BODY DBMS_OUTPUT AS
PROCEDURE PUT_LINE(pString IN VARCHAR2) AS
BEGIN
SELECT pString;
END;
END DBMS_OUTPUT;
//

BEGIN
DBMS_OUTPUT.PUT_LINE('Hello world from MariaDB
DBMS_OUTPUT.PUT_LINE!');
END;
//
DELIMITER ;

Where PL/SQL can be Problematic
● PL/SQL is an extension to SQL, not a replacement
● PL/SQL is sequential row by row processing, SQL is
Set Processing
● Pure SQL solution can be faster than SQL with PL/SQL
● Avoid external tables (CONNECT Engine in MariaDB)

PL/SQL and Database Load
● PL/SQL is executed in the Database Kernel
● Causes more CPU requirements in Database Server
● Causes need for Larger System
● Harder Horizontal Scaling
● No way to offload CPU cycles to Client Machines

Blue Azure
#0E6488
Sea Fresh
#96DDCF
Granite
#424F62
Brand Guidelines
Colors and Type
Open Seas
#2F99A3
Deep Ocean
#003545
Electric Eel
#AC74A

Icons
Company
MariaDB Server ColumnStore MaxScale

Icons
Social
Facebook Twitter LinkedIn YouTubeGoogle+

Writing powerful stored procedures in PL/SQL

More Related Content

What's hot (20)

Similar to Writing powerful stored procedures in PL/SQL (20)

More from MariaDB plc (20)

Recently uploaded (20)

Writing powerful stored procedures in PL/SQL