Row data retrieval

Retrieve row data from a table by performing the following general tasks:

Construct a SELECT SQL statement in a String variable.
Create a PreparedStatement object by passing the String variable to the Connection.prepareStatement method.
Call the PreparedStatement.executeQuery method to assign the query results to a ResultSet object.
Traverse through the ResultSet object using the navigational methods to retrieve the row data.

The following navigational methods can be used to traverse a result set:
- afterLast¹ Position immediately after the last row.
- beforeFirst¹ Position immediately before the first row.
- first¹ Move to the first row.
- last¹ Move to the last row.
- next Move to the next row.
- previous Move to the previous row.
- relative(offset)¹ Move a specified number of rows relative to the current row, as specified by the signed offset value. Positive offset values move forward in the result set, relative to the current pointer position in the result set. Negative offset values move backward in the result set. An offset value of zero does not move the current location, but allows you to repopulate the row buffer.
¹ This method is not supported for UltraLite Java edition databases.
Close the ResultSet and PreparedStatement objects to free resources.

Example

The code referenced in this example is part of a complete sample that illustrates how to perform basic schema and data management operations using the UltraLiteJ API. See Example: Managing database operations on an Android smartphone.

A result set is retrieved in the custom SelectDepartmentRows method:

public ResultSet SelectDepartmentRows() {
    String stmt = "SELECT * FROM Department ORDER BY dept_no";
    _preparer = null;
    _departments = null;
    try {
        _preparer = _conn.prepareStatement(stmt);
        _departments = _preparer.executeQuery();
        PrintText("Successfully executed: " + stmt);
    } catch (ULjException e) {
        HandleError(e);
    }
    return _departments;
}

Row data is retrieved by traversing through a result set using the next navigational method:

_departments = SelectDepartmentRows();
if (_departments != null) {
    try {
        while(_departments.next()) {
            int dept_no = _departments.getInt(1);
            String dept_name = _departments.getString(2);
            PrintText("Department no.:" + dept_no
                    + " Department name: " + dept_name);
        }
    } catch (ULjException e) {
        HandleError(e);
    }
}

Row data retrieval

Example

See also