MariaDB + Visual Studio 2017 环境下的 ODBC 入门开发
参考:
环境:
- Windows 10 x64 1803
- MariaDB TX 10.2.14 x64
- MariaDB ODBC Connector 3.0.3 x64
- Visual Studio 2017 Community 15.6.7
安装ODBC驱动并配置数据源:
先安装ODBC驱动。根据自身需求选择32或64位版本。我选择了64位版本。
打开ODBC数据源管理程序,点击右侧的“添加”按钮,添加用户DSN。如图操作。
后面按照默认配置,点击Next即可。
编写ODBC程序:
1 引入头文件:
#include <iostream> #include <windows.h> #include <sqlext.h>
2 定义一个检查错误的宏:
#define ODBC_CHECK(x) \ {\ if (!SQL_SUCCEEDED(x))\ {\ std::cout << "SQL error occurred at line " << __LINE__ << ".";\ getchar();\ exit(-1);\ }\ }
3 ODBC初始化,为ODBC分配环境句柄
(分配环境句柄:注意,这里使用了新版的ODBC API SQLAllocHandle,而不是SQLAllocEnv)
// SQL Handle of ENVironment SQLHENV env; ODBC_CHECK(SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env)); // SQLAllocEnv ODBC_CHECK(SQLSetEnvAttr(env, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0));
4 建立应用程序与ODBC数据源的连接
(分配连接句柄:注意,这里使用了新版的ODBC API SQLAllocHandle,而不是SQLAllocConnect)
// SQL Handle of DB Connection SQLHDBC dbc; SQLCHAR dbcConfOut[256]; ODBC_CHECK(SQLAllocHandle(SQL_HANDLE_DBC, env, &dbc)); // SQLAllocConnect ODBC_CHECK(SQLSetConnectAttr(dbc, SQL_LOGIN_TIMEOUT, (SQLPOINTER)5, 0));
(连接数据源:可以使用SQLConnect,也可以使用SQLDriverConnect;可以手动指定DSN名字,也可以通过弹出窗口来指定)
// specify manually ODBC_CHECK(SQLDriverConnect(dbc, NULL, (SQLCHAR *)"DSN=MariaDB;", SQL_NTS, dbcConfOut, sizeof(dbcConfOut), NULL, SQL_DRIVER_COMPLETE)); // SQLConnect // specify by popup window //ODBC_CHECK(SQLDriverConnect(dbc, GetDesktopWindow(), NULL, SQL_NTS, // dbcConfOut, sizeof(dbcConfOut), NULL, SQL_DRIVER_COMPLETE)); // SQLConnect
(显示连接成功的信息)
std::cout << "Connected!" << std::endl << "ConnStrIn = " << dbcConfOut << std::endl; SQLCHAR dbmsName[256]; ODBC_CHECK(SQLGetInfo(dbc, SQL_DBMS_NAME, (SQLPOINTER)dbmsName, sizeof(dbmsName), NULL)); SQLCHAR dbmsVer[256]; ODBC_CHECK(SQLGetInfo(dbc, SQL_DBMS_VER, (SQLPOINTER)dbmsVer, sizeof(dbmsVer), NULL)); std::cout << "DBMS Name = " << dbmsName << std::endl << "DBMS Version = " << dbmsVer << std::endl;
(分配语句句柄:注意,这里使用了新版的ODBC API SQLAllocHandle,而不是SQLAllocStmt)
// SQL Handle of STateMenT SQLHSTMT stmt; ODBC_CHECK(SQLAllocHandle(SQL_HANDLE_STMT, dbc, &stmt)); // SQLAllocStmt
5 利用SQLExecDirect语句,实现数据库应用程序对数据库的建立、查询、修改、删除等
(建立一个循环,一直接收并执行用户的SQL的语句,直到用户退出)
const int queryLen = 1024; SQLCHAR query[queryLen]; std::cout << "Please input your SQL query. Type CTRL+Z to quit." << std::endl << dbmsName << " >"; while (fgets((char*)query, queryLen - 1, stdin)) { if (query[0] == '\n') { std::cout << dbmsName << " >"; continue; } switch (SQLExecDirect(stmt, query, SQL_NTS)) { case SQL_SUCCESS_WITH_INFO: case SQL_SUCCESS: { SQLSMALLINT col; SQLNumResultCols(stmt, &col); // SELECT if (col > 0) { // 2 methods: SQLGetData() and SQLBindCol() // SQLGetData() is adopted here char buf[512]; SQLUSMALLINT colidx; // print column names for (colidx = 1; colidx <= col; ++colidx) { SQLColAttribute(stmt, colidx, SQL_DESC_NAME, buf, sizeof(buf), NULL, NULL); std::cout << buf << " "; } std::cout << std::endl; // iterate each row unsigned row = 0; // row counter while (SQL_SUCCEEDED(SQLFetch(stmt))) { ++row; // iterate each column for (colidx = 1; colidx <= col; ++colidx) { SQLLEN indicator; if (SQL_SUCCEEDED(SQLGetData(stmt, colidx, SQL_C_CHAR, buf, sizeof(buf), &indicator))) { if (indicator == SQL_NULL_DATA) strcpy(buf, "NULL"); std::cout << buf << " "; } } std::cout << std::endl; } if (row == 1) { std::cout << "1 row in set." << std::endl; } else { std::cout << row << " rows in set." << std::endl; } } // CREATE, UPDATE, DELETE, etc. else { SQLLEN row; ODBC_CHECK(SQLRowCount(stmt, &row)); if (row == 1) { std::cout << "1 row affected." << std::endl; } else { std::cout << row << " rows affected." << std::endl; } } break; } case SQL_ERROR: { std::cout << "Returned SQL_ERROR." << std::endl; break; } default: { std::cout << "Unknown SQLRETURN." << std::endl; } } ODBC_CHECK(SQLFreeStmt(stmt, SQL_CLOSE)); std::cout << dbmsName << " >"; }
6 检索查询结果集
7 结束数据库应用程序
// release resources ODBC_CHECK(SQLFreeHandle(SQL_HANDLE_STMT, stmt)); ODBC_CHECK(SQLDisconnect(dbc)); ODBC_CHECK(SQLFreeHandle(SQL_HANDLE_DBC, dbc)); ODBC_CHECK(SQLFreeHandle(SQL_HANDLE_ENV, env)); return 0;