query =从table_name中选择count(*)，其中user_id = user_id";
sqlcommand sql =新的sqlcommand(查询，连接);
datareader reader = sql.executescalar();
int number_of_records = reader.RowCount;



现在，如果您有一个存储d与会者的列，则可以执行以下操作:
从表名中选择列名，其中用户=用户名

query = "select count(*) from table_name where user_id = user_id";
sqlcommand sql = new sqlcommand(query, connection);
datareader reader = sql.executescalar();
int number_of_records = reader.RowCount;



now if you have a column that stores d attendace, u can do this:
select column_name from table_name where user = user_name

在此处阅读有关ADO.NET的信息，它将对您有所帮助.

看看这些:
MSDN:ADO.NET [ MSDN:使用ADO.NET访问数据 [ ^ ]

C#Station ADO.NET教程 [为初学者使用ADO.NET [

Read about ADO.NET here and it will help you.

Look at these:
MSDN: ADO.NET[^]
MSDN: Accessing Data with ADO.NET[^]

The C# Station ADO.NET Tutorial[^]
Using ADO.NET for beginners[^]