The ODBC driver supports conversions of XML values to and from both ODBC Character C types (SQL_C_CHAR and SQL_C_WCHAR) and the Binary C type SQL_C_BINARY.
XML data type values retrieved from the database may be complete XML documents, but also non-well-formed text entities, including XML document fragments, such as sequences or atomic values. XML data type values inserted into the database must be XML documents (well-formed).
The recommended conversion of XML is to or from SQL_C_BINARY or SQL_C_WCHAR because it eliminates conversion to a non-Unicode code page used by the application, which can result in conversion errors. The default ODBC C type for SQL_TD_XML is SQL_C_BINARY.
| XML represented as | Description |
|---|---|
| SQL_C_BINARY | The value is a sequence of characters encoded in UTF-8 regardless of any encoding declaration in the XML text. |
| SQL_C_CHAR | The value is a sequence of characters encoded in the application code page regardless of any encoding declaration in the XML text. |
| SQL_C_WCHAR | The value is a sequence of characters encoded in the Unicode encoding in effect for the application (UTF-8 or UTF-16 for Linux/Unix. UTF-16 for Windows, UTF-32 for Apple OS X). The encoding is independent of any encoding declaration in the XML text. |
For a given XML document the recommended ODBC C type for working with the document in ODBC depends on the XML document encoding as determined by the XML declaration in the document.
| XML Document Encoding Declaration | Recommended ODBC C type for working with the document in an ODBC application | ||
|---|---|---|---|
| Windows | Linux/Unix | Apple OS X | |
| UTF-8 | SQL_C_BINARY or SQL_C_WCHAR. Note that when using SQL_C_WCHAR the encoding will be UTF-16 | SQL_C_BINARY or SQL_C_WCHAR. | SQL_C_BINARY or SQL_C_WCHAR |
| UTF-16 | SQL_C_WCHAR | SQL_C_WCHAR with UTF-16 Unicode encoding as described in Unicode Character Types. | SQL_C_WCHAR |
| Other | SQL_C_CHAR using application code page matching document encoding | SQL_C_CHAR using an application code page matching the XML document encoding. | SAL_C_CHAR with locale LC_TYPE setting matching the document encoding. |