Ssp class php where clause

SQL WHERE Clause


The SQL WHERE Clause

The clause is used to filter records.

It is used to extract only those records that fulfill a specified condition.

WHERE syntax

SELECT column1, column2, ...
FROM table_name
WHERE condition;

Grade: The clause is not only used in statements, it is also used in,, etc.!


Demo database

Below is a selection from the "Customers" table in the Northwind sample database:

CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry
1

Alfred's feed boxMaria AndersObere Str. 57Berlin12209Germany
2Ana Trujillo Emparedados y heladosAna TrujilloAvda. de la Constitución 2222México D.F.05021Mexico
3Antonio Moreno TaqueríaAntonio MorenoMataderos 2312México D.F.05023Mexico
4

Around the hornThomas Hardy120 Hanover Sq.LondonWA1 1DPUK
5Berglunds snabbköpChristina BerglundBerguvsvägen 8LuleåS-958 22Sweden


WHERE Clause Example

The following SQL statement selects all the customers from the country "Mexico", in the "Customers" table:


Text fields vs. numeric fields

SQL requires single quotes around text values ​​(most database systems will also allow double quotes).

However, numeric fields should not be enclosed in quotes:


Operators in The WHERE Clause

The following operators can be used in the clause:

operatorDescriptionExample
=EqualTry it
>Greater thanTry it
<Less thanTry it
>=Greater than or equalTry it
<=Less than or equalTry it
<>Not equal. Grade: In some versions of SQL this operator may be written as! =Try it
BETWEENBetween a certain rangeTry it
LIKESearch for a patternTry it
INTo specify multiple possible values ​​for a columnTry it