Database Reference
In-Depth Information
6
In this chapter, you learn how to use the
SELECT
statement's
WHERE
clause to
specify search conditions.
Database tables usually contain large amounts of data, and you seldom need
to retrieve all the rows in a table. More often than not, you want to extract a
subset of the table's data as needed for specific operations or reports. Retrieving
just the data you want involves specifying
search criteria
, also known as a
filter
condition
.
Within a
SELECT
statement, data is filtered by specifying search criteria in the
WHERE
clause. The
WHERE
clause is specified right after the table name (the
FROM
clause) as follows:
▼
Input
SELECT prod_name, prod_price
FROM products
WHERE prod_price = 2.50;
▼
Analysis
This statement retrieves two columns from the
products
table, but instead of
returning all rows, only rows with a
prod_price
value of
2.50
are returned,
as follows:
▼
Output
+---------------+------------+
| prod_name | prod_price |
+---------------+------------+
| Carrots | 2.50 |
| TNT (1 stick) | 2.50 |
+---------------+------------+
