Persisting a Result Set as an XML Data File

The DataDirect Connect Series for ODBC drivers allow you to persist a result set as an XML data file with embedded schema. To implement XML persistence, a client application must do the following:

1	Turn on STATIC cursors. For example:

SQLSetStmtAttr (hstmt, SQL_ATTR_CURSOR_TYPE, SQL_CURSOR_STATIC, SQL_IS_INTEGER)

NOTE: A result set can be persisted as an XML data file only if the result set is generated using STATIC cursors. Otherwise, the following error is returned:

Driver only supports XML persistence when using driver’s static cursors.

2	Execute a SQL statement. For example:

SQLExecDirect (hstmt, "SELECT * FROM GTABLE", SQL_NTS)

3	Persist the result set as an XML data file. For example:

SQLSetStmtAttr (hstmt, SQL_PERSIST_AS_XML, "C:\temp\GTABLE.XML", SQL_NTS)

NOTE: A statement attribute is available to support XML persistence, SQL_PERSIST_AS_XML. A client application must call SQLSetStmtAttr with this attribute as an argument. See the following table for the definition of valid arguments for SQLSetStmtAttr.

Argument	Definition
StatementHandle	The handle of the statement that contains the result set to persist as XML.
Attribute	SQL_PERSIST_AS_XML. This statement attribute can be found in the file qesqlext.h, which is installed with the driver.
ValuePtr	Pointer to a URL that specifies the full path name of the XML data file to be generated. The directory specified in the path name must exist, and if the specified file name exists, the file will be overwritten.
StringLength	The length of the string pointed to by ValuePtr or SQL_NTS if ValuePtr points to a NULL-terminated string.

A client application can choose to persist the data at any time that the statement is in an executed or cursor-positioned state. At any other time, the driver returns the following message:

Function Sequence Error

Using the Windows XML Persistence Demo Tool

The 32-bit drivers for Windows are shipped with an XML persistence demo tool. This tool is installed in the product installation directory.

The tool has a graphical user interface and allows you to persist data as an XML data file.

To use the Windows XML Persistence Demo tool:

1	From the product program group, select XML Persistence Demo. The XMLPersistence dialog box appears.

2	First, you must connect to the database. Click Connect. The Select Data Source dialog box appears.

3	You must either select an existing data source or create a new one. Take one of the following actions:

■	Select an existing data source and click OK.

■	Create a new file data source by clicking New. The Create New Data Source dialog box appears. Follow the instructions in the dialog box.

■	Create a new machine data source by clicking the Machine Data Source tab and clicking New. The Create New Data Source dialog box appears. Follow the instructions in the dialog box.

4	After you have connected to a database, type a SQL Select statement in the Query text box of the XML Persistence dialog box. Then, click Persist. The Save As dialog box appears.

5	Specify a name and location for the XML data file that will be created. Then, click OK.

Note that the Status box in the XML Persistence dialog box displays whether the action failed or succeeded.

6	Click Disconnect to disconnect from the database.

7	Click Close to exit the tool.

Using the UNIX/Linux XML Persistence Demo Tool

On UNIX and Linux, the drivers are shipped with an XML persistence demo tool named demoodbc. This tool is installed in the installation directory, in the /samples/demo subdirectory. For information about how to use this tool, refer to the demoodbc.txt file installed in the demo subdirectory.