firebird-mirror/doc/sql.extensions/README.call.md

CALL statement (FB 6.0)

CALL statement is similar to EXECUTE PROCEDURE, but allow the caller to get specific output parameters, or none.

When using the positional or mixed parameter passing, output parameters follows the input ones.

When passing NULL to output parameters, they are ignored, and in the case of DSQL, not even returned.

In DSQL output parameters are specified using ?, and in PSQL using the target variables or parameters.

Syntax

<call statement> ::=
    CALL [<package name> .] <procedure name> (<arguments>)

<arguments> ::=
    <positional arguments> |
    [ {<positional arguments>,} ] <named arguments>

<positional arguments> ::=
    <value or default> [ {, <value or default>}... ]

<named arguments> ::=
    <named argument> [ {, <named argument>}... ]

<named argument> ::=
    <argument name> => <value or default>

<value or default> ::=
    <value> |
    DEFAULT

Examples

create or alter procedure insert_customer (
    last_name varchar(30),
    first_name varchar(30)
) returns (
    id integer,
    full_name varchar(62)
)
as
begin
    insert into customers (last_name, first_name)
        values (:last_name, :first_name)
        returning id, last_name || ', ' || first_name
        into :id, :full_name;
end

-- Not all output parameters are necessary.
call insert_customer(
    'LECLERC',
    'CHARLES',
    ?)

-- Ignore first output parameter (using NULL) and get the second.
call insert_customer(
    'LECLERC',
    'CHARLES',
    null,
    ?)

-- Ignore ID output parameter.
call insert_customer(
    'LECLERC',
    'CHARLES',
    full_name => ?)

-- Pass inputs and get outputs using named arguments.
call insert_customer(
    last_name => 'LECLERC',
    first_name => 'CHARLES',
    last_name => ?,
    id => ?)

create or alter procedure do_something_and_insert_customer returns (
    out_id integer,
    out_full_name varchar(62)
)
as
    declare last_name varchar(30);
    declare first_name varchar(30);
begin
    call insert_customer(
        last_name,
        first_name,
        out_id,
        full_name => out_full_name);
end