WHERE Clause
Eliminates rows from the result table that do not satisfy one or more predicates.
Syntax
WHERE boolean-expression [ subquery ] ...
Parameters
boolean-expression |
Is an expression that returns true or false. Only rows for which the expression is true become part of the result set. |
The boolean-expression can include Boolean Operators and the following elements:
- BETWEEN-predicate
- Boolean-Predicate
- Column-Value-Predicate
- IN-predicate
- Join-Predicate
- LIKE-predicate
- NULL-predicate
Notes
You can use parentheses to group expressions, predicates, and boolean operators. For example:
=> ... WHERE NOT (A=1 AND B=2) OR C=3;
Example
The following example returns the names of all customers in the Eastern region whose name starts with 'Amer'. Without the WHERE clause filter, the query returns all customer names in the customer_dimension table.
=> SELECT DISTINCT customer_name FROM customer_dimension WHERE customer_region = 'East' AND customer_name ILIKE 'Amer%'; customer_name --------------- Americare Americom Americore Americorp Ameridata Amerigen Amerihope Amerimedia Amerishop Ameristar Ameritech (11 rows)
