获取数据表返回值一直是空的,帮帮我吧,

[lkj182878142]

string sql = "select max(id) from ChatRoomLog";
DAL.ExecuteSql exec = new ExecuteSql();
DataTable table = new DataTable();
exec.run(sql, table);
string str = table.Rows[0][0].ToString();
int id = 0;
if (table.Rows[0][0].ToString() == "")
{
id = 1;
}
else
{
id = Convert.ToInt32(table.Rows[0][0].ToString()) + 1;
}
在这里调试str的值一直是""的,到下面id的值也一直是0,
为什么会这样啊,
table.rows.count()是有结果的,哪位大侠帮帮我吧,