DISTINCT Predicate

Specifies that only unique rows can appear in the result table.

Syntax

Arguments

Details

Example

Syntax

Form 1:

function DISTINCT (expression);

Form 2:

row-value-constructor IS DISTINCT FROM row-value-constructor

Form 3:

SELECT DISTINCT <select-list> FROM <table-expression>;

Arguments

function

can be any aggregate function.

expression

specifies any valid SQL expression.

See	<sql-expression>
	FedSQL Expressions

row-value constructor

specifies any row value expression that represents a row value.

See	Row Value Expressions

SELECT <select-list> FROM <table-expression>

is a query that retrieves rows from a table.

See	For more information about using the DISTINCT predicate in the SELECT statement, see the SELECT Clause.

Details

You can use the DISTINCT predicate to compare two values or two row values to see whether they are equal to one another. The DISTINCT predicate evaluates to true only if all rows that its subquery returns are distinct.

Note: Two null values are not considered distinct.

Example

select count(distinct avghigh) from worldtemps;

(42, 47,15) is distinct from (42, 47, 15)

select distinct c1.employee, firstname, salary
   from company as c1;

DISTINCT Predicate

Syntax

Form 1:

Form 2:

Form 3:

Arguments

function

expression

row-value constructor

SELECT <select-list> FROM <table-expression>

Details

Example

See Also