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Core Interface Conformance

  • Άρθρο

All ODBC drivers must exhibit at least Core-level interface conformance. Because the features in the Core level are those required by most generic interoperable applications, the driver can work with such applications. The features in the Core level also correspond to the features defined in the ISO CLI specification and to the nonoptional features defined in the Open Group CLI specification. A Core-level interface-conformant ODBC driver allows the application to do all of the following:

  • Allocate and free all types of handles, by calling SQLAllocHandle and SQLFreeHandle.

  • Use all forms of the SQLFreeStmt function.

  • Bind result set columns, by calling SQLBindCol.

  • Handle dynamic parameters, including arrays of parameters, in the input direction only, by calling SQLBindParameter and SQLNumParams. (Parameters in the output direction are feature 203 in Level 2 Interface Conformance.)

  • Specify a bind offset.

  • Use the data-at-execution dialog, involving calls to SQLParamData and SQLPutData.

  • Manage cursors and cursor names, by calling SQLCloseCursor, SQLGetCursorName, and SQLSetCursorName.

  • Gain access to the description (metadata) of result sets, by calling SQLColAttribute, SQLDescribeCol, SQLNumResultCols, and SQLRowCount. (Use of these functions on column number 0 to retrieve bookmark metadata is feature 204 in Level 2 Interface Conformance.)

  • Query the data dictionary, by calling the catalog functions SQLColumns, SQLGetTypeInfo, SQLStatistics, and SQLTables.

    The driver is not required to support multipart names of database tables and views. (For more information, see feature 101 in Level 1 Interface Conformance and feature 201 in Level 2 Interface Conformance.) However, certain features of the SQL-92 specification, such as column qualification and names of indexes, are syntactically comparable to multipart naming. The present list of ODBC features is not intended to introduce new options into these aspects of SQL-92.

  • Manage data sources and connections, by calling SQLConnect, SQLDataSources, SQLDisconnect, and SQLDriverConnect. Obtain information on drivers, no matter which ODBC level they support, by calling SQLDrivers.

  • Prepare and execute SQL statements, by calling SQLExecDirect, SQLExecute, and SQLPrepare.

  • Fetch one row of a result set or multiple rows, in the forward direction only, by calling SQLFetch or by calling SQLFetchScroll with the FetchOrientation argument set to SQL_FETCH_NEXT.

  • Obtain an unbound column in parts, by calling SQLGetData.

  • Obtain current values of all attributes, by calling SQLGetConnectAttr, SQLGetEnvAttr, and SQLGetStmtAttr, and set all attributes to their default values and set certain attributes to nondefault values by calling SQLSetConnectAttr, SQLSetEnvAttr, and SQLSetStmtAttr.

  • Manipulate certain fields of descriptors, by calling SQLCopyDesc, SQLGetDescField, SQLGetDescRec, SQLSetDescField, and SQLSetDescRec.

  • Obtain diagnostic information, by calling SQLGetDiagField and SQLGetDiagRec.

  • Detect driver capabilities, by calling SQLGetFunctions and SQLGetInfo. Also, detect the result of any text substitutions made to a SQL statement before it is sent to the data source, by calling SQLNativeSql.

  • Use the syntax of SQLEndTran to commit a transaction. A Core-level driver need not support true transactions; therefore, the application cannot specify SQL_ROLLBACK nor SQL_AUTOCOMMIT_OFF for the SQL_ATTR_AUTOCOMMIT connection attribute. (For more information, see feature 109 in Level 2 Interface Conformance.)

  • Call SQLCancel to cancel the data-at-execution dialog and, in multithread environments, to cancel an ODBC function executing in another thread. Core-level interface conformance does not mandate support for asynchronous execution of functions, nor the use of SQLCancel to cancel an ODBC function executing asynchronously. Neither the platform nor the ODBC driver need be multithread for the driver to conduct independent activities at the same time. However, in multithread environments, the ODBC driver must be thread-safe. Serialization of requests from the application is a conformant way to implement this specification, even though it might create serious performance problems.

  • Obtain the SQL_BEST_ROWID row-identifying column of tables, by calling SQLSpecialColumns. (Support for SQL_ROWVER is feature 208 in Level 2 Interface Conformance.)

    Important

    ODBC Drivers must implement the functions in the Core interface conformance level.