fg.cpp

这个是sql嵌入到c语言中的例子 原来：EXEC SQL CONNECT TO SKY.exp USER sa.sa //连接到数据库 更改：EXEC SQL CONNECT TO 8BC1D82

#include <stdio.h>
#include <iostream.h>
#include <string.h>
#include <windows.h>
#include <sql.h>
#include <sqlext.h>
#include <odbcss.h>

#define MAXBUFLEN   255	
#define MaxNameLen  20

#define SQLBINDCOL

SQLHENV      henv = SQL_NULL_HENV;//定义环境句柄
SQLHDBC      hdbc1 = SQL_NULL_HDBC;//定义数据库连接句柄     
SQLHSTMT      hstmt1 = SQL_NULL_HSTMT;//定义语句句柄
int main() 
{
	RETCODE retcode;//错误返回码
	
    // Allocate the ODBC Environment and save handle.
	retcode = SQLAllocHandle (SQL_HANDLE_ENV, NULL, &henv);	
	if(retcode < 0 )//错误处理
	{
		cout<<"allocate ODBC Environment handle errors."<<endl;
		return -1;
	}

	// Notify ODBC that this is an ODBC 3.0 application.
	retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION,
		(SQLPOINTER) SQL_OV_ODBC3, SQL_IS_INTEGER);
	if(retcode < 0 ) //错误处理
	{
		cout<<"the  ODBC is not version3.0 "<<endl;
		return -1;
	}
	
	// Allocate an ODBC connection and connect.
	retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc1);
	if(retcode < 0 ) //错误处理
	{
		cout<<"allocate ODBC connection handle errors."<<endl;
		return -1;
	}

	//Data Source Name must be of type User DNS or System DNS
	char* szDSN = "sqlhw";
	char* szUID = "sa";//log name
	char* szAuthStr = "";//passward

	//connect to the Data Source
	retcode=SQLConnect(hdbc1,(SQLCHAR*)szDSN,(SWORD)strlen(szDSN),(SQLCHAR*)szUID, (SWORD)strlen(szUID),(SQLCHAR*)szAuthStr, (SWORD)strlen(szAuthStr));
	if(retcode < 0 ) //错误处理
	{		
		cout<<"connect to  ODBC datasource errors."<<endl;
		return -1;
	}

	// Allocate a statement handle.
	retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc1, &hstmt1);
	if(retcode < 0 ) //错误处理
	{
		cout<<"allocate ODBC statement handle errors."<<endl;
		return -1;
	}
	
	// Execute an SQL statement directly on the statement handle.每一句后面都跟了一个错误处理，当发生错误时可以很方便的判断错在哪里
	
	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"create table provider (sno char(5) primary key,sname char(10) not null,status int,city char(10))", SQL_NTS);
	if(retcode<0) 
	{
		cout<<"creat errors."<<endl;
		return -1;
	}								
	
	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"insert into provider values('S1','精益','20','天津')",SQL_NTS);
	if(retcode<0) 
	{
		cout<<"s1 insert errors."<<endl;
		return -1;
	}

	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"insert into provider values('S2','胜锡','10','北京')",SQL_NTS);
	if(retcode<0) 
	{
		cout<<"s2 insert errors."<<endl;
		return -1;
	}

	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"insert into provider values('S3','东方红','30','天津')",SQL_NTS);
	if(retcode<0) 
	{
		cout<<"s3 insert errors."<<endl;
		return -1;
	}

	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"insert into provider values('S4','丰泰盛','20','天津')",SQL_NTS);
	if(retcode<0) 
	{
		cout<<"s4 insert errors."<<endl;
		return -1;
	}

	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"insert into provider values('S5','为民','30','上海')",SQL_NTS);
	if(retcode<0) 
	{
		cout<<"s5 insert errors."<<endl;
		return -1;
	}

	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"insert into provider values('S6','通天','25',null)",SQL_NTS);
	if(retcode<0) 
	{
		cout<<"s6 insert errors."<<endl;
		return -1;
	}

	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"SElECT sname,city  FROM provider where sno='s1'", SQL_NTS);
	if(retcode < 0 )
	{
		cout<<"Executing statement  throught ODBC  errors."<<endl;
		return -1;
	}
/*	retcode = SQLExecDirect(hstmt1,(SQLCHAR*)"drop table provider", SQL_NTS);
	if(retcode<0) 
	{
		cout<<"drop errors."<<endl;
		return -1;
	}*/

	// SQLBindCol variables
	SQLCHAR      city[MaxNameLen + 1];	
	SQLCHAR		 name[MaxNameLen + 1];
	SQLINTEGER   columnLen = 0;//数据库定义中该属性列的长度

#ifdef SQLBINDCOL
	
//游标已被封装在其中，一开始把两个列号分别写为provider中的列号2（name），4（city），结果name的值为city的值，city的值为烫烫烫烫烫烫烫烫，这才发现第二个参数应为游标中的列号，而不是表中的列号，
	retcode = SQLBindCol(hstmt1, 1, SQL_C_CHAR,name,MaxNameLen , &columnLen); 
	retcode = SQLBindCol(hstmt1, 2, SQL_C_CHAR,city,MaxNameLen , &columnLen);
	while ( (retcode = SQLFetch(hstmt1) ) != SQL_NO_DATA) 
	{		
		if(columnLen>0)
			printf("name = %s  city = %s\n", name,city);
		else
			printf("name = %s  city = NULL\n", name,city);
	}
	
		   
	
#else
	
	while(1 )
	{
		retcode = SQLFetch(hstmt1);
		if(retcode == SQL_NO_DATA)
		break;
		
		retcode = SQLGetData(hstmt1, 1, SQL_C_CHAR, name, MaxNameLen, &columnLen);
		retcode = SQLGetData(hstmt1, 2, SQL_C_CHAR, city, MaxNameLen, &columnLen);		
		if(columnLen>0)
			printf("name = %s  city = %s\n", name,city);
		else
			printf("name = %s  city = NULL\n", name,city);
		
	}

#endif
	

	/* Clean up.*/
	SQLFreeHandle(SQL_HANDLE_STMT, hstmt1);
	SQLDisconnect(hdbc1);
	SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
	SQLFreeHandle(SQL_HANDLE_ENV, henv);
	
	return(0);
}