ODBC连数据库代码 - C接口 - 备忘

最新推荐文章于 2021-11-16 17:45:28 发布

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#数据库 #c #sql #buffer #user

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本文介绍了一个使用ODBC进行数据库连接及数据查询的具体实例。包括环境设置、连接数据库、执行SQL语句、获取结果集并打印数据等步骤。

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1. 声明变量

2. 为DB连接分配内存

SQLAllocEnv (&hEnv); // Allocate memory for ODBC Environment handle SQLAllocConnect (hEnv, &hDBC); // Allocate memory for the connection handle

3. 连接数据库

retcode = SQLConnect (hDBC, szDSN, SQL_NTS, szUID,SQL_NTS, szPasswd, SQL_NTS);

4. 执行SQL, 绑定变量到SQL返回的column

retcode = SQLAllocStmt (hDBC, &hStmt); // Allocate memory for the statementhandle retcode = SQLPrepare (hStmt, szSqlStr,wcslen(szSqlStr)); // Prepare the SQL statement by assigningit to the statement handle retcode = SQLExecute (hStmt); // Execute the SQL statement handle // Project only column 1 which is the models SQLBindCol (hStmt, 1, SQL_C_CHAR, szModel,sizeof(szModel), &cbModel);

5. 取得返回结果

// Get row of data from the result set defined above in the statement retcode = SQLFetch (hStmt); while (retcode == SQL_SUCCESS || retcode== SQL_SUCCESS_WITH_INFO) { printf ("inv_ref_id=%s, %d/t",szModel, sizeof(szModel)); // Print row(model) retcode = SQLFetch(hStmt); // Fetch next row from result set }

6. 释放内存

SQLFreeStmt (hStmt, SQL_DROP); // Free the allocated statement handle SQLDisconnect (hDBC); // Disconnect from datasource SQLFreeConnect (hDBC); // Free the allocated connection handle SQLFreeEnv (hEnv); // Free the allocated ODBC environment handle

7. 结束了, 完整代码

HENV hEnv = NULL; // Env Handle from SQLAllocEnv() HDBC hDBC = NULL; // Connection handle HSTMT hStmt = NULL; // Statement handle TCHAR szDSN[SQL_MAX_DSN_LENGTH] =L"SYB_DEV_re"; // Data Source Name buffer TCHAR* szUID = L"ccms";// User ID buffer TCHAR* szPasswd = L"ccmsccms";// Password buffer TCHAR szModel[128];// Model buffer SDWORD cbModel;// Model buffer bytes recieved // SQL string TCHAR szSqlStr[] = L"Select inv_ref_id FROM inv_ref"; RETCODE retcode;// Return code SQLAllocEnv (&hEnv); // Allocate memory for ODBC Environment handle SQLAllocConnect (hEnv, &hDBC); // Allocate memory for the connection handle // Connect to the data source "SYB_DEV_re" using userid and password. retcode = SQLConnect (hDBC, szDSN, SQL_NTS, szUID,SQL_NTS, szPasswd, SQL_NTS); if (retcode == SQL_SUCCESS || retcode ==SQL_SUCCESS_WITH_INFO) { printf("CONNECTED/n"); retcode = SQLAllocStmt (hDBC, &hStmt); // Allocate memory for the statementhandle retcode = SQLPrepare (hStmt, szSqlStr,wcslen(szSqlStr)); // Prepare the SQL statement by assigningit to the statement handle retcode = SQLExecute (hStmt); // Execute the SQL statement handle // Project only column 1 which is the models SQLBindCol (hStmt, 1, SQL_C_CHAR, szModel,sizeof(szModel), &cbModel); // Get row of data from the result set defined above in the statement retcode = SQLFetch (hStmt); while (retcode == SQL_SUCCESS || retcode== SQL_SUCCESS_WITH_INFO) { printf ("inv_ref_id=%s/n",szModel); // Print row(model) retcode = SQLFetch(hStmt); // Fetch next row from result set } SQLFreeStmt (hStmt, SQL_DROP); // Free the allocated statement handle SQLDisconnect (hDBC); // Disconnect from datasource } SQLFreeConnect (hDBC); // Free the allocated connection handle SQLFreeEnv (hEnv); // Free the allocated ODBC environment handle return 0;