SQL多字段模糊查询

http://user.qzone.qq.com/382164370#!app=2&via=QZ.HashRefresh&pos=1346996967

代码是在VC++里面:

	CString sql, str;
	sql.Format(_T("SELECT * FROM tbPatient WHERE admitDate	BETWEEN CDate('%s %s') AND CDate('%s %s')"),
		dtStartDate.Format(_T("%x")), dtStartTime.Format(_T("%X")),
		dtEndDate.Format(_T("%x")), dtEndTime.Format(_T("%X")));


	//字段合并的模糊查询 MYSQL concat(email,address) like 'like%df%'
	if(!strKeyWord.IsEmpty())
	{
		//SQL Server中IsNull(expression, replace)有替换功能, 
		//Access需要结合IsNull ( expression ), iif (condition, value_if_true, value_if_false )函数
		
		//str.Format(_T(" AND IsNull(name, ' ') & IsNull(Empid, ' ') LIKE '%%%s%%'"), 
		//	strKeyWord.GetBuffer(0));


		str.Format(_T(" AND iif(IsNull(name),' ',name) & iif(IsNull(Empid),' ',Empid) LIKE  '%%%s%%'"), 
			strKeyWord.GetBuffer(0));


		sql += str;
	}


	TRACE1("%s\n", sql);

一种改写的代码

CString sql, str;
	sql.Format(_T("SELECT * FROM tbPatient"));
	
	if (!m_bDisplayAll)		//非全部显示则添加搜索条件
	{
		str.Format(_T(" WHERE admitDate	BETWEEN CDate('%s %s') AND CDate('%s %s')"),
			dtStartDate.Format(_T("%x")), dtStartTime.Format(_T("%X")),
			dtEndDate.Format(_T("%x")), dtEndTime.Format(_T("%X")));


		sql += str;


		//字段合并的模糊查询 MYSQL concat(email, address) like 'like%df%'
		if(!strKeyWord.IsEmpty())
		{
			//SQL Server中IsNull(expression, replace)有替换功能, 
			//Access需要结合IsNull ( expression ), iif (condition, value_if_true, value_if_false )函数


			//str.Format(_T(" AND IsNull(name, ' ') + IsNull(Empid, ' ') LIKE '%%%s%%'"), 
			//	strKeyWord.GetBuffer(0));


			str.Format(_T(" AND iif(IsNull(name),' ',name) & iif(IsNull(Empid),' ',Empid) LIKE  '%%%s%%'"), 
				strKeyWord.GetBuffer(0));


			sql += str;
		}
	}


	//sql += _T(" ORDER BY ASC");			//DESC, 添加排序


	TRACE1("%s\n", sql);