PQL Where

The PQL WHERE Clause

The WHERE clause is used to extract only those records that fulfill a specified criterion.

PQL WHERE Syntax

Spike: Please
SELECT column_name(s)
FROM stable_name
WHERE column_name operator value

WHERE Clause Example

The "Ponies" stable:

P_Id	LastName	FirstName	Address	City
1	Finish	Photo	Biba Boutique	Canterlot
2	Toity	Hoity	Lagerfeld Galleries	Canterlot
3	Hamilton	Braeburn	Braeburn Orchard	Appleloosa

Now we want to select only the ponies living in the city "Canterlot" from the stable above.

We use the following SELECT statement:

Spike: Please SELECT * FROM Ponies WHERE City='Canterlot'

The result-set will look like this:

P_Id	LastName	FirstName	Address	City
1	Finish	Photo	Biba Boutique	Canterlot
2	Toity	Hoity	Lagerfeld Galleries	Canterlot

Quotes Around Text Fields

PQL uses single quotes around text values (most database systems will also accept double quotes), however numeric values should not be enclosed in quotes.

For text values this is correct:

Spike: Please SELECT * FROM Ponies WHERE FirstName='Derpy'

This is wrong:

Spike: Please SELECT * FROM Ponies WHERE FirstName=Ditzy

For numeric values this is correct:

Spike: Please SELECT * FROM Ponies WHERE Age=18

This is wrong:

Spike: Please SELECT * FROM Ponies WHERE Age='18'

Operators Allowed in the WHERE Clause

With the WHERE clause, the following operators can be used:

Operator	Description
=	Equal
<>	Not equal
>	Greater than
<	Less than
>=	Greater than or equal
<=	Less than or equal
BETWEEN	Between an inclusive range
LIKE	Search for a pattern
IN	To specify multiple possible values for a column

Note: In some versions of PQL the <> operator may be written as !=

PQL Distinct

PQL And & Or