c++连接sql server数据库代码

以下是一个简单的 C++ 连接 SQL Server 数据库的示例代码：

首先，你需要包含以下头文件：

#include <iostream>
#include <windows.h>
#include <sqltypes.h>
#include <sql.h>
#include <sqlext.h>

然后，你需要定义连接数据库所需的一些变量，如下所示：

SQLHANDLE sqlenvhandle;
SQLHANDLE sqlconnectionhandle;
SQLHANDLE sqlstatementhandle;
SQLRETURN retcode;
SQLCHAR retconstring[1024];

接下来，初始化环境句柄和连接句柄：

SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &sqlenvhandle);
SQLSetEnvAttr(sqlenvhandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
SQLAllocHandle(SQL_HANDLE_DBC, sqlenvhandle, &sqlconnectionhandle);

然后，设置连接属性：

SQLCHAR connectionstring[] = "DRIVER={SQL Server};SERVER=server_name;DATABASE=database_name;UID=user_name;PWD=password";
retcode = SQLDriverConnect(sqlconnectionhandle, NULL, connectionstring, SQL_NTS, retconstring, 1024, NULL, SQL_DRIVER_NOPROMPT);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
    std::cout << "Connected to SQL Server successfully." << std::endl;
}

在连接成功后，你可以执行 SQL 查询语句，如下所示：

SQLAllocHandle(SQL_HANDLE_STMT, sqlconnectionhandle, &sqlstatementhandle);
SQLCHAR query[] = "SELECT * FROM table_name";
retcode = SQLExecDirect(sqlstatementhandle, query, SQL_NTS);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
    // 处理查询结果
}

最后，释放句柄和关闭连接：

SQLFreeHandle(SQL_HANDLE_STMT, sqlstatementhandle);
SQLDisconnect(sqlconnectionhandle);
SQLFreeHandle(SQL_HANDLE_DBC, sqlconnectionhandle);
SQLFreeHandle(SQL_HANDLE_ENV, sqlenvhandle);

完整代码示例：

#include <iostream>
#include <windows.h>
#include <sqltypes.h>
#include <sql.h>
#include <sqlext.h>

int main() {
    SQLHANDLE sqlenvhandle;
    SQLHANDLE sqlconnectionhandle;
    SQLHANDLE sqlstatementhandle;
    SQLRETURN retcode;
    SQLCHAR retconstring[1024];

    SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &sqlenvhandle);
    SQLSetEnvAttr(sqlenvhandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
    SQLAllocHandle(SQL_HANDLE_DBC, sqlenvhandle, &sqlconnectionhandle);

    SQLCHAR connectionstring[] = "DRIVER={SQL Server};SERVER=server_name;DATABASE=database_name;UID=user_name;PWD=password";
    retcode = SQLDriverConnect(sqlconnectionhandle, NULL, connectionstring, SQL_NTS, retconstring, 1024, NULL, SQL_DRIVER_NOPROMPT);
    if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
        std::cout << "Connected to SQL Server successfully." << std::endl;
    }

    SQLAllocHandle(SQL_HANDLE_STMT, sqlconnectionhandle, &sqlstatementhandle);
    SQLCHAR query[] = "SELECT * FROM table_name";
    retcode = SQLExecDirect(sqlstatementhandle, query, SQL_NTS);
    if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
        // 处理查询结果
    }

    SQLFreeHandle(SQL_HANDLE_STMT, sqlstatementhandle);
    SQLDisconnect(sqlconnectionhandle);
    SQLFreeHandle(SQL_HANDLE_DBC, sqlconnectionhandle);
    SQLFreeHandle(SQL_HANDLE_ENV, sqlenvhandle);

    return 0;
}