用Visual C++开发数据库应用程序(二)(3)

返回值:

SQL_SUCCESS, SQL_SUCCESS_WITH_INFO, SQL_ERROR, or SQL_INVALID_HANDLE.

成功返回SQL_SUCCESS，如果返回值为SQL_ERROR或SQL_SUCCESS_WITH_INFO，可以用函数SQLGetDiagRec获取相应SQLSTATE的值。　

下面的代码演示了如何使用ODBC API的SQLConnect函数建立同数据源SQLServer的连接。　

#include “sqlext.h”

SQLHENV henv;;

SQLHDBC hdbc;

SQLHSTMT hstmt;

SQLRETURN retcode;

/*Allocate environment handle */

retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {

/* Set the ODBC version environment attribute */

retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0);

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {

/* Allocate connection handle */

retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {

/* Set login timeout to 5 seconds. */

SQLSetConnectAttr(hdbc, (void*)SQL_LOGIN_TIMEOUT, 5, 0);

/* Connect to data source */

retcode = SQLConnect(hdbc, (SQLCHAR*) "Sales", SQL_NTS,

(SQLCHAR*) "JohnS", SQL_NTS,

(SQLCHAR*) "Sesame", SQL_NTS);

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO){

/* Allocate statement handle */

retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);

if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {