On Feb 5, 2005, at 11:20 PM, Karl O. Pinc wrote:
Is this example telling me I get NULL for unitialized references? I don't believe I should count on this behavior unless it's documented, should I?
=> create or replace function foo() returns int language plpgsql as 'declare a int; b int; begin a := b; return a; end; '; CREATE FUNCTION => select foo();
Yes, exactly. If you don't assign a value to a declared pspgsql variable, it is NULL. Operations on NULL variables are no different than operations on NULL values in the database. If you are concerned about this, then always assign a value when you declare it.
Also, you can specify NOT NULL in your declaration to ensure a runtime error is generated if the variable is null. See:
http://www.postgresql.org/docs/8.0/interactive/plpgsql-declarations.html
The general syntax of a variable declaration is:
name [ CONSTANT ] type [ NOT NULL ] [ { DEFAULT | := } expression ];The DEFAULT clause, if given, specifies the initial value assigned to the variable when the block is entered. If the DEFAULT clause is not given then the variable is initialized to the SQL null value. The CONSTANT option prevents the variable from being assigned to, so that its value remains constant for the duration of the block. If NOT NULL is specified, an assignment of a null value results in a run-time error. All variables declared as NOT NULL must have a nonnull default value specified.
John DeSoi, Ph.D. http://pgedit.com/ Power Tools for PostgreSQL
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