C++通过ODBC连接数据库

来源：互联网发布：男生淘宝编辑：程序博客网时间：2024/05/22 05:05

有很多种连接数据库的方法，得一种一中的钻研学习，

这里，我用的是一种比较基本的比较老的数据库连接方法，就是通过微软给提供的ODBC SQLAPI库来连接

具体的原理，我就不在这掉书袋了，大家都大体清楚，深层的就没有研究过。

先贴出直接查询的代码：

#include <windows.h>#include <stdio.h>#include <sql.h>#include <stdlib.h>#include <sqlext.h>#include <string.h>#include <iostream>/* *一般情况下,如果返回的错误码retcode < 0,就说明没有处理得当,就是错误的 */using namespace std;int main(){HENV henv;HDBC hdbc;HSTMT hstmt;RETCODE retcode;SQLAllocEnv(&henv);SQLAllocConnect(henv, &hdbc);retcode = SQLConnect(hdbc,(unsigned char *)"myDB", SQL_NTS, NULL, 0, NULL, 0);//cout << retcode << endl;if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO){cout << "连接成功" << endl;}else{cout << "连接失败" << endl;}retcode = SQLAllocStmt(hdbc, &hstmt);retcode = SQLExecDirect(hstmt, (unsigned char*)"SELECT * FROM student", SQL_NTS);char *sno = new char[256];char *sname = new char[256];char *ssex = new char[256];char *sage = new char[256];char *sdept = new char[256];long columnlen;SQLBindCol(hstmt, 1, SQL_CHAR, sno, 256, &columnlen);//这个语句可不能写错,里面的256,代表的是字符串的最大长度.SQLBindCol(hstmt, 2, SQL_CHAR, sname, 256, &columnlen);SQLBindCol(hstmt, 3, SQL_CHAR, ssex, 256, &columnlen);SQLBindCol(hstmt, 4, SQL_CHAR, sage, 256, &columnlen);SQLBindCol(hstmt, 5, SQL_CHAR, sdept, 256, &columnlen);if (retcode < 0){cout << "没有执行语句" << endl;}retcode = SQLFetch(hstmt);while (retcode == SQL_ROW_SUCCESS || retcode == SQL_ROW_SUCCESS_WITH_INFO){if (retcode == SQL_ROW_SUCCESS || retcode == SQL_ROW_SUCCESS_WITH_INFO){printf("%s\t%s\t%s\t%s\t%s\n", sno, sname, ssex, sage, sdept);retcode = SQLFetch(hstmt);}}SQLFreeConnect(hdbc);SQLFreeEnv(henv); return 0;}