asp.net SqlParameter如何根据条件有选择的添加参数

 
public UserInfo GetAll(UserInfo a) 
{ 
string strSql = "select id,name,code,password from [tb].[dbo].[User] where 1=1"; 
strSql += " and [id]=@id"; 
strSql += " and [name]=@name"; 
strSql += " and [code]=@code"; 
strSql += " and [password]=@password"; 
SqlParameter[] parameters = { 
new SqlParameter("@id", a.id) 
new SqlParameter("@name", a.name) 
new SqlParameter("@code", a.code), 
new SqlParameter("@password", a.password) 
}; 
SqlDataReader reader = SqlHelper.ExecuteReader(strSql, parameters); 
UserInfo hc = new UserInfo(); 
while(reader.Read()) 
{ 
hc.id = reader.GetInt32(reader.GetOrdinal("id")); 
hc.name = reader.GetString(reader.GetOrdinal("name")); 
hc.code = reader.GetString(reader.GetOrdinal("code")); 
hc.password = reader.GetString(reader.GetOrdinal("password")); 
} 
reader.Close(); 
return hc; 
} 

 
public UserInfo GetALL(UserInfo a) 
{ 
string strSql = "select id,name,code,password from [tb].[dbo].[User] where 1=1"; 
if (a.id>0) strSql += " and [id]=@id"; 
if (!string.IsNullOrEmpty(a.name)) strSql += " and [name]=@name"; 
if (!string.IsNullOrEmpty(a.code)) strSql += " and [code]=@code"; 
if (!string.IsNullOrEmpty(a.password)) strSql += " and [password]=@password"; 
List<SqlParameter> parametertemp = new List<SqlParameter>(); 
if (a.id > 0) parametertemp.Add(new SqlParameter("@id", a.id)); 
if (!string.IsNullOrEmpty(a.name)) parametertemp.Add(new SqlParameter("@name", a.name)); 
if (!string.IsNullOrEmpty(a.code)) parametertemp.Add(new SqlParameter("@code", a.code)); 
if (!string.IsNullOrEmpty(a.password)) parametertemp.Add(new SqlParameter("@password", a.password)); 
SqlParameter[] parameters = parametertemp.ToArray();//ToArray()方法将 List<T> 的元素复制到新数组中。 

SqlDataReader reader = SqlHelper.ExecuteReader(strSql, parameters); 
UserInfo hc = new UserInfo(); 
while (reader.Read()) 
{ 
hc.id = reader.GetInt32(reader.GetOrdinal("id")); 
hc.name = reader.GetString(reader.GetOrdinal("name")); 
hc.code = reader.GetString(reader.GetOrdinal("code")); 
hc.password = reader.GetString(reader.GetOrdinal("password")); 
} 
reader.Close(); 
return hc; 
} 

 
public SqlDataReader ExecuteReader(string query, params SqlParameter[] parameters) 
{ 
SqlConnString = GetConnect2(); 
SqlConnString.Open(); 
SqlCommand SqlCmd = new SqlCommand(); 
SqlCmd.Connection = SqlConnString; 
SqlCmd.CommandText = query; 
//SqlCmd.Parameters.AddRange(parameters);//AddRange()不能传空参数组 
//params 的意思就是允许传空参数组 
foreach (SqlParameter item in parameters) 
{ 
SqlCmd.Parameters.Add(item); 
} 
SqlDataReader dr; 
try 
{ 
dr = SqlCmd.ExecuteReader(CommandBehavior.CloseConnection); 
return dr; 
} 
catch (Exception ee) 
{ 
SqlConnString.Close(); 
throw ee; 
} 
}