private string m_str_variationInfo = @"SELECT variationinfoMngno
FROM sellersandvariationmngtbl
WHERE sellerCD= @sellerCD
";
//处理
MySqlParameter[] MySqlParameter = new MySqlParameter[1];
MySqlParameter[0] = new MySqlParameter("@sellerCD", prm_sellerCD);
object val = DataAccess.ExecuteScalar(prm_con, CommandType.Text, m_str_variationInfo, MySqlParameter);
return val;
判断val是否为空即可只读该数据存不存在。
原文：http://www.cnblogs.com/ouyangxiaoyao/p/5728365.html