-- Scalar function syntax
CREATE|ALTER FUNCTION [ schema_name. ] function_name
( [ { @param_name [ AS ]
          [ type_schema_name. ] param_data_type
    [ = default ] [ READONLY ] }
    [ ,...n ]
  ]
)
RETURNS return_data_type
    [ WITH <function_option> [ ,...n ] ]
    [ AS ]
    BEGIN
        function_body
        RETURN scalar_expression
    END
[ ; ]


-- Table-Valued function syntax
CREATE|ALTER FUNCTION [ schema_name. ] function_name
( [ { @param_name [ AS ]
        [ type_schema_name. ] param_data_type
    [ = default ] [ READONLY ] }
    [ ,...n ]
  ]
)
RETURNS TABLE
    [ WITH <function_option> [ ,...n ] ]
    [ AS ]
    RETURN [ ( ] select_stmt [ ) ]
[ ; ]