Database

SELECT COUNT(*) AS NumberOfRecords FROM Login

public static int GetRecordsInTable(string table, SqlConnection con)
{
  SqlCommand cmd = new SqlCommand(
    String.Format("SELECT COUNT(*) AS X FROM [{0}]", table), con);
  con.Open();
  object r = cmd.ExecuteScalar();
  con.Close();
  return (int) r; //oops missed the cast
}

SELECT DATE_FORMAT(Accessi.Data, '%Y/%m/%d') AS Giorno, Count(DATE_FORMAT(Accessi.Data, '%Y/%m/%d')) AS Accessi
FROM Accessi
WHERE Giorno BETWEEN convert(datetime,'2002/12/1') AND convert(datetime,'2002/12/31')
GROUP BY Giorno

SELECT DayOfYear(Accessi.Data) as numGiorno, Accessi.Data, Count(Accessi.Data) AS Accessi
FROM Accessi GROUP BY numGiorno 
HAVING numGiorno BETWEEN DayOfYear('2002/12/1') AND DayOfYear('2002/12/31') AND Year(Accessi.Data) = 2002

IF EXISTS (SELECT name FROM sysobjecs WHERE id = object_id(N'tablename')
    AND OBJECTPROPERTY(id, N'IsUserTable') = 1)
    SELECT * FROM tablename

SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES

exec('select * from sysobjects where ' +  @myColumnName + ' >5')