In addition to defining as single statement in a function using a RETURN, you can specify compound statements (multiple statements) wrapped in BEGIN ATOMIC and END. The following demonstrates the syntax along with supported typical declarations and statements. See the following topics for more information about supported statements and syntax. 

BEGIN ATOMIC
         <table_variable_declaration>;
         <scalar_variable_declaration>;
         <cursor_declaration>;
         <handler_declaration>;
         <procedural_statement>;
         RETURN <expression>;
         END

where:

table-variable-declaration
(optional) defines the variable name, column names, and data types for a temporary table to be created. For example, DECLARE TABLE mytable (id INTEGER, employees VARCHAR(32));. See Table declarations for more information.
scalar_variable_declaration
(optional) defines the variable name and data type for a value to be stored. For example, DECLARE max_event TIMESTAMP;. See Scalar declarations for more information.
cursor_declaration
(optional) defines the cursor that allows procedures to return table values as result sets. See "Cursor declaration" for details and syntax. See Cursor declarations for more information.
handler_declaration
(optional) defines a handler used for exception handling. See Handler declarations for more information.
procedural_statement
defines DQL, DML, DDL, and SQL procedural statements used to execute the routine. See Procedural SQL statements for more information.
expression
is the argument that determines the value to be returned.