---
title: "Describing Parameters"
description: "Describing Parameters"
author: David-Engel
ms.author: davidengel
ms.date: "01/19/2017"
ms.service: sql
ms.subservice: connectivity
ms.topic: conceptual
helpviewer_keywords:
  - "SQLBindParameter function [ODBC], describing parameters"
---
# Describing Parameters
**SQLBindParameter** has arguments that describe the parameter: its SQL type, precision, and scale. The driver uses this information, or *metadata,* to convert the parameter value to the type needed by the data source. At first glance, it might seem that the driver is in a better position to know the parameter metadata than the application; after all, the driver can easily discover the metadata for a result set column. As it turns out, this is not the case. First, most data sources do not provide a way for the driver to discover parameter metadata. Second, most applications already know the metadata.  
  
 If a SQL statement is hard-coded in the application, the application writer already knows the type of each parameter. If a SQL statement is constructed by the application at run time, the application can determine the metadata as it builds the statement. For example, when the application constructs the clause  
  
```  
WHERE OrderID = ?  
```  
  
 it can call **SQLColumns** for the OrderID column.  
  
 The only situation in which the application cannot easily determine the parameter metadata is when the user enters a parameterized statement. In this case, the application calls **SQLPrepare** to prepare the statement, **SQLNumParams** to determine the number of parameters, and **SQLDescribeParam** to describe each parameter. However, as was noted earlier, most data sources do not provide a way for the driver to discover parameter metadata, so **SQLDescribeParam** is not widely supported.