# Statement

  sql holder and executer. JDBC has three statement classes: Statement, PreparedStatement, and CallableStatement. RDBC has only one statement class.

## class methods:

  ``

## methods:

  `initialize(con, sql=nil)`

    You dont have to call it yourself. if sql==nil then self is non-prepared. else self is prepared.

  `execute(sql=nil)`

    execute sql. if sql==nil then prepared sql is executed. else the sql is executed.
    returns true if a ResultSet object is made. return false if updatecount>=0.

  `executeQuery(sql=nil)`

    execute. throws an exception if ResultSet object is not made. returns the ResultSet object.

  `executeUpdate(sql=nil)`

    execute. throws an exception if updatecount < 0. returns updatecount.

  `close`

  `setParam(index, data)`

    if prepared, you can "set a data to a parameter". index is a name(String) of the parameter.

  `getParam(index)`

    if prepared, you can "get a data from a parameter". index is a name(String) of the parameter.

  `resultset`

    returns recent ResultSet object. executeUpdate discards(nil) the object.

  `updatecount`

    returns recent updatecount. executeQuery discards(-1) the value.