关于C连接SQL Server数据库的问题
本人刚刚开始接触数据库,想用C连接数据库,进行insert等操作。我参考了网上的代码后,最后写出来的代码是这样的:
#pragma comment(lib,"odbc32.lib")
#pragma comment(lib,"odbccp32.lib")
#include<stdio.h>
#include<string.h>
#include<Windows.h>
#include<sql.h>
#include<sqlext.h>
#include<sqltypes.h>
#include<odbcss.h>
#define MAXBUFLEN 255
SQLHENV henv=SQL_NULL_HENV;
SQLHDBC hdbc1=SQL_NULL_HDBC;
SQLHSTMT hstmt1=SQL_NULL_HSTMT;
/*
cpp文件功能说明:
1.数据库操作中的添加,修改,删除,主要体现在SQL语句上
2.采用直接执行方式和参数预编译执行方式两种
*/
int main()
{
RETCODE retcode; //预编译SQL语句
CHAR pre_sql[225] = "delete from test where a='1' ";
CHAR ConnStrIn[MAXBUFLEN] = "DRIVER={SQL Server}; SERVER=(local);UID=sa; PWD=123456;Trusted_Connection=yes;DATABASE=test; ";
SQLWCHAR Wpre_sql[225];
SQLWCHAR WConnStrIn[MAXBUFLEN];
MultiByteToWideChar(CP_UTF8, 0, pre_sql, strlen(pre_sql), Wpre_sql, sizeof Wpre_sql / sizeof *Wpre_sql);
MultiByteToWideChar(CP_UTF8, 0, ConnStrIn, strlen(ConnStrIn), WConnStrIn, sizeof WConnStrIn / sizeof *WConnStrIn);
//1.连接数据源
//1.环境句柄
retcode = SQLAllocHandle(SQL_HANDLE_ENV,NULL ,&henv); /*第二个参数原NULL*/
retcode = SQLSetEnvAttr(henv,SQL_ATTR_ODBC_VERSION,(SQLPOINTER)SQL_OV_ODBC3,SQL_IS_INTEGER);
//2.连接句柄
retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc1);
retcode = SQLDriverConnect(hdbc1,NULL,WConnStrIn,SQL_NTS,NULL,NULL,NULL,SQL_DRIVER_NOPROMPT);
//retcode = SQLConnect(hdbc1,NULL,SQL_NTS,(SQLWCHAR*)"sa",SQL_NTS,(SQLWCHAR*) "123456",SQL_NTS);
if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) )
{
printf("连接失败!\n");
}
//判断连接是否成功
/*if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) )
{
printf("连接失败!\n");
}
else
{ */
/*
1.分配一个语句句柄(statement handle)
2.创建SQL语句
3.执行语句
4.销毁语句
*/
retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc1, &hstmt1);
//第一种方式
//直接执行
//添加操作
//SQLExecDirect (hstmt1,sql,37);
//第二种方式
//绑定参数方式
char a[200]="bbb";
char b[200]="200";
SQLINTEGER p = SQL_NTS;
//1预编译
retcode=SQLPrepare(hstmt1,Wpre_sql,29); //第三个参数与数组大小相同,而不是数据库列相同
if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) )
{
printf("连接失败!\n");
}
//2绑定参数值
/*retcode=SQLBindParameter(hstmt1,1,SQL_PARAM_INPUT,SQL_C_CHAR,SQL_CHAR,200,0,&a,0,&p);
if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) )
{
printf("连接失败!\n");
}
retcode=SQLBindParameter(hstmt1,2,SQL_PARAM_INPUT,SQL_C_CHAR,SQL_CHAR,200,0,&b,0,&p);
if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) )
{
printf("连接失败!\n");
} */
//3 执行
retcode=SQLExecute(hstmt1);
SQLWCHAR SqlState[6],SQLStmt[100],Msg[255];
SQLINTEGER NativeError;
SQLSMALLINT i=1,MsgLen;
if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) )
{
printf("连接失败!\n");
while(SQLGetDiagRec(SQL_HANDLE_STMT,hstmt1,i,SqlState,&NativeError,Msg,sizeof(Msg),&MsgLen)!=SQL_NO_DATA)
{
i++;
}
}
printf("操作成功!");
//释放语句句柄
SQLCloseCursor (hstmt1);
SQLFreeHandle (SQL_HANDLE_STMT, hstmt1);
//}
//3.断开数据库连接
/*
1. 断开数据库连接
2.释放连接句柄.
3.释放环境句柄(如果不再需要在这个环境中作更多连接)
*/
SQLDisconnect(hdbc1);
SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return(0);
}
问题是pre_sql如果是insert 或者 update的话 会在SQLExecute后报错,但是delete不会。请大神求指教