asp.net SqlParameter如何根据条件有选择的添加参数_实用技巧_

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 parametertemp = new List();
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 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;
}
}