The WHERE clause is used to filter records.
It is used to extract only those records that meet a certain condition.
SELECT column1, column2, ...
FROM table_name
WHERE condition
The following is a sample from the "Customers" table of the "Northwind" database:
| CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
|---|---|---|---|---|---|---|
| 1 | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
| 2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 5021 | Mexico |
| 3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 5023 | Mexico |
| 4 | Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
| 5 | Berglunds snabbköp | Christina Berglund | Berguvsvägen 8 | Luleå | S-958 22 | Sweden |
The following SQL statement selects all customers from the country "Mexico" in the table "Customers":
Run SQLSELECT * FROM Customers
WHERE Country = 'Mexico'
SQL requires single quotes around text values (most database systems also allow double quotes).
However, numeric fields should not be enclosed in quotes:
Run SQLSELECT * FROM Customers
WHERE CustomerID = 1
The following statements can be used with a WHERE clause:
| Operator | Description |
|---|---|
| = | Equal |
| > | Greater than |
| < | Less than |
| >= | Greater than or equal |
| <= | Less than or equal |
| <> | Not equal to Note: In some versions of SQL, this operator may be written as != |
| BETWEEN | Between a certain range (inclusively) |
| LIKE | Search for a pattern |
| IN | To specify multiple possible values for a column |
