SQL Where

January 21st, 2012

The WHERE statement is used to retrieve if you want to limit data extracted based on certain criteria. The ebasic syntax for DISTINCT is as follows

SELECT column1, column2
WHERE column(s) operator value
FROM table;

WHERE Example Usage

The Persons Table

ID	First_Name	Last_Name	Gender	Occupation
123	Fabian	Salvador	Male	Fireman
543	James	Parker	Male	Wrestler
345	Abigail	Grant	Female	Fireman
223	Chloe	Strange	Female	Secretary
545	Emma	Rogers	Female	Model
275	Gwen	Watson	Female	Model
522	Stephen	Rogers	Male	Salesman

If we want to retrieve the persons with the Last_Name of Rogers, our SQL Statement would look like this:

SELECT *
FROM Persons
WHERE Last_Name = 'Rogers'

The result would look like this:

ID	First_Name	Last_Name	Gender	Occupation
545	Emma	Rogers	Female	Model
522	Stephen	Rogers	Male	Salesman

If we want to select the Male Persons from the Persons table, our SQL statement would look like this

SELECT *
FROM Persons
WHERE Gender = 'Male'

ID	First_Name	Last_Name	Gender	Occupation
123	Fabian	Salvador	Male	Fireman
543	James	Parker	Male	Wrestler
545	Emma	Rogers	Female	Model
522	Stephen	Rogers	Male	Salesman

Using SELECT DISTINCT and WHERE together

ID	First_Name	Last_Name	Gender	Occupation
123	Fabian	Salvador	Male	Fireman
543	James	Parker	Male	Wrestler
345	Abigail	Grant	Female	Fireman
223	Chloe	Strange	Female	Secretary
545	Emma	Rogers	Female	Model
275	Gwen	Watson	Female	Model
522	Stephen	Rogers	Male	Salesman

In this example we would like to retrieve the Occupations of Female persons and we don’t like duplicates.

SELECT DISTINCT Occupation
FROM Persons
WHERE Gender = 'Female'

The result will be as follows:

Occupation
Fireman
Secretary
Model

PinoyTech.org

SQL Where

WHERE Example Usage

Using SELECT DISTINCT and WHERE together