Statement Terminators

Some SQL statement editors — specifically the isql utility that comes with Firebird, and possibly some third-party editors — employ an internal convention that requires all statements to be terminated with a semicolon.This creates a conflict with PSQL syntax when coding in these environments.If you are unacquainted with this problem and its solution, please study the details in the PSQL chapter in the section entitled Switching the Terminator in isql.

Parameters

Each parameter has a data type.

A collation can be specified for string-type parameters, using the COLLATE clause.

Input Parameters: Input parameters are presented as a parenthesized list following the name of the function.They are passed by value into the function, so any changes inside the function has no effect on the parameters in the caller.The NOT NULL constraint can also be specified for any input parameter, to prevent NULL being passed or assigned to it.Input parameters may have default values.Parameters with default values specified must be added at the end of the list of parameters.
Output Parameter: The RETURNS clause specifies the return type of the stored function.If a function returns a string value, then it is possible to specify the collation using the COLLATE clause.As a return type, you can specify a data type, a domain, the type of a domain (using TYPE OF), or the type of a column of a table or view (using TYPE OF COLUMN).