==============
DESCRIBE INPUT
==============

Synopsis
--------

.. code-block:: none

    DESCRIBE INPUT statement_name

Description
-----------

Describes the input parameters for a prepared statement. It returns a table
with the position and type of each parameter. If the type of the parameter can
not be determined, unknown is returned.

Examples
--------

Prepare and describe a query with three parameters:

.. code-block:: sql

    PREPARE my_select1 FROM
    SELECT ? FROM nation WHERE regionkey = ? AND name < ?;

.. code-block:: sql

       DESCRIBE INPUT my_select1;

.. code-block:: none

       Position | Type
       ------------------
              0 | unknown
              1 | bigint
              2 | varchar
       (3 rows)

Prepare and describe a query with no parameters:

.. code-block:: sql

    PREPARE my_select2 FROM
    SELECT * FROM nation;

.. code-block:: sql

       DESCRIBE INPUT my_select2;

.. code-block:: none

       Position | Type
       ---------------
      (0 rows)

See Also
--------

:doc:`prepare`