My sql udf,views
Download as PPTX, PDF0 likes706 views
This document discusses user defined functions (UDF) and views in MySQL. It provides the syntax for creating UDFs and views. UDFs allow users to define reusable functions that can be called from queries. Views act as virtual tables that are based on the result set of a SELECT statement. The document provides an example of creating a UDF to return the number of jobs applied by a user and an example of creating a view from an employee table to select employee IDs and names. It describes some key properties and limitations of UDFs and how views can be used to rename attributes and insert/delete data.
My sql udf,views
- 2. NikhilDevS.B nikhildevsb@gmail.com www.facebook.com/nikhildevsb TwitterProfile www.linkedin.com/nikhildevsb Typing speed: 24 wpm. USER DEFINED FUNCTIONS AND VIEWS IN MYSQL
- 3. Disclaimer: This presentation is prepared by trainees of baabtra.com as a part of mentoring program. This is not official document of baabtra.com – Mentoring Partner
- 4. User Defined functions (UDF) • It is the SQL routines used to encapsulate program logic. • A function is a set of codes written to perform certain task.
- 5. • UDF cant call a Stored Procedure. • Functions are compiled and executed at run time thus it slower than stored procedure.
- 6. Syntax : creating a UDF DELIMITER // CREATE FUNCTION function_name (parameter datatype) RETURNS datatype BEGIN <statements> ............ ............ END // DELIMITER ; Syntax : Calling a function SELECT function_name(parameter);
- 7. E.g. : DELIMITER // CREATE FUNCTION fun_checkNum(int_x int) RETURNS varchar(20) NO SQL BEGIN DECLARE numtype varchar(25); IF(int_x<0) THEN SET numtype='Negative Number'; ELSE SET numtype='Positive Number'; END IF; RETURN numtype; END // DELIMITER; //Calling Function and output : mysql> SELECT fun_checkNum(-1); +------------------+ | fun_checkNum(-1) | +------------------+ | Negative Number | +------------------+
- 8. PECULIARITIES OF USER DEFINED FUNCTIONS • UDF are compiled and Executed at run time. • UDF must return a value. • UDF can only have input parameters. • UDF can be called from stored procedure. • A UDF can call another UDF. • UDF allows only SELECT command in it, no other DML,DDL,DCL commands.
- 9. Problem1: Write a user defined function to return how many jobs applied by a user. DELIMITER // CREATE FUNCTION fun_jobsApplied(getID int) RETURNS int READS SQL DATA BEGIN DECLARE count int; SELECT int_jobs_applied into count FROM tbl_jobs where int_id=getID; RETURN count; END // DELIMITER ; SELECT fun_jobsApplied(1); //calling udf, it returns number of applied jobs corresponding to id=1
- 10. Views in Mysql
- 11. Views • In SQL, a VIEW is a virtual relation based on the result set of a SELECT statement. • A view can be considered as a stored query or a virtual table. • A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database. • View Doesn't take any storage space.
- 12. Syntax: CREATE VIEW view_name AS SELECT column_name(s) FROM table_name WHERE condition;
- 13. pk_int_emp_id vchr_emp_name vchr_company 1 James Dell 2 John Sony 3 Albert Hp CREATE VIEW vw_tbl_employee AS SELECT pk_int_emp_id , vchr_emp_name FROM tbl_employee; SELECT * FROM vw_tbl_employee; //to see all content of view E.g. VIEW Creating a view for below table pk_int_emp_id vchr_emp_name 1 James 2 John 3 Albert
- 14. Renaming Attributes in View • Sometime, we might want to distinguish attributes by giving the different name from names in table . CREATE VIEW vw_tbl_employee (Employeeid,EmployeeName) AS SELECT pk_int_emp_id , vchr_emp_name FROM tbl_employee; SELECT * FROM vw_tbl_employee; Employeeid EmployeeName 1 James 2 John 3 Albert
- 15. Insert values to view We can insert value into view as same as that of table INSERT INTO vw_tbl_employee (Employeename) VALUES (‘Smith’); Employeeid EmployeeName 1 James 2 John 3 Albert 4 Smith
- 16. Delete from view DELETE FROM vw_tbl_employee WHERE Employeeid=1; Employeeid EmployeeName 2 John 3 Albert 4 Smith DROP VIEW DROP VIEW viewname; DROP VIEW vw_tbl_employee;
- 17. Thank you...
- 18. Want to learn more about programming or Looking to become a good programmer? Are you wasting time on searching so many contents online? Do you want to learn things quickly? Tired of spending huge amount of money to become a Software professional? Do an online course @ baabtra.com We put industry standards to practice. Our structured, activity based courses are so designed to make a quick, good software professional out of anybody who holds a passion for coding.
- 19. Follow us @ twitter.com/baabtra Like us @ facebook.com/baabtra Subscribe to us @ youtube.com/baabtra Become a follower @ slideshare.net/BaabtraMentoringPartner Connect to us @ in.linkedin.com/in/baabtra Give a feedback @ massbaab.com/baabtra Thanks in advance www.baabtra.com | www.massbaab.com |www.baabte.com
- 20. Emarald Mall (Big Bazar Building) Mavoor Road, Kozhikode, Kerala, India. Ph: + 91 – 495 40 25 550 NC Complex, Near Bus Stand Mukkam, Kozhikode, Kerala, India. Ph: + 91 – 495 40 25 550 Cafit Square, Hilite Business Park, Near Pantheerankavu, Kozhikode Start up Village Eranakulam, Kerala, India. Email: info@baabtra.com Contact Us