Java Doc for ResultSet.java in  » Apache-Harmony-Java-SE » java-package » java » sql » Java Source Code / Java DocumentationJava Source Code and Java Documentation

ResultSets have a Cursor which points to a current row of data. When a ResultSet is created, the Cursor is positioned before the first row. To move the Cursor to the next row in the table, use the next method. The next method returns true until there are no more rows in the ResultSet, when it returns false.

The default type of ResultSet cannot be updated and its cursor can only move forward through the rows of data. This means that it is only possible to read through it once. However, it is possible to create types of ResultSet that can be updated and also types where the cursor can be scrolled forward and backward through the rows of data. This is shown in the following code example: Connection con; Statement aStatement = con.createStatement( ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE ); ResultSet theResultSet = theStatement.executeQuery("SELECT price, quantity FROM STOCKTABLE"); // theResultSet will be both scrollable and updateable

The ResultSet interface provides a series of methods for retrieving data from columns in the current row, such as getDate, getFloat. The columns are identified either by their index number (starting at 1) or by their name - there are separate methods for both techniques of column addressing. The column names are case insensitive. If several columns have the same name, then the getter methods use the first matching column. This means that if column names are used, it is not possible to guarantee that the name will retrieve data from the intended column - for certainty it is better to use column indexes. Ideally the columns should be read left-to-right and read once only, since not all * databases are optimized to handle other techniques of reading the data.

When reading data, the JDBC driver maps the SQL data retrieved from the database to the Java type implied by the method invoked by the application. The JDBC specification has a table of allowable mappings from SQL types to Java types.

There are also methods for writing data into the ResultSet, such as updateInt, updateString. The update methods can be used either to modify the data of an existing row or to insert new data rows into the ResultSet. Modification of existing data involves moving the Cursor to the row which needs modification and then using the update methods to modify the data, followed by calling the ResultSet.updateRow method. For insertion of new rows, the cursor is first moved to a special row called the Insert Row, data is added using the update methods, followed by calling the ResultSet.insertRow method.

A ResultSet is closed if the Statement object which generated it closed, executed again or is used to retrieve the next result from a sequence of results.

This method can be used to read LONGVARBINARY values.

This method can be used to read LONGVARBINARY values.

The type of the Java object will be determined by the supplied Map to perform the mapping of SQL Struct or Distinct types into Java objects.
Parameters:
  columnIndex - the index of the column to read
Parameters:
  map - a java.util.Map containing a mapping from SQL Type names toJava classes.

The type of the Java object will be determined by the supplied Map to perform the mapping of SQL Struct or Distinct types into Java objects.
Parameters:
  columnName - the name of the column to read
Parameters:
  map - a java.util.Map containing a mapping from SQL Type names toJava classes.

This method can be used to read LONGVARBINARY values. All of the data in the InputStream should be read before getting data from any other column. A further call to a getter method will implicitly close the InputStream.
Parameters:
  columnIndex - the index of the column to read an InputStream with the data from the column. If the column valueis SQL NULL, null is returned.
throws:
  SQLException - if a database error happens

This method can be used to read LONGVARBINARY values. All of the data in the InputStream should be read before getting data from any other column. A further call to a getter method will implicitly close the InputStream.
Parameters:
  columnName - the name of the column to read an InputStream with the data from the column If the column valueis SQL NULL, null is returned.
throws:
  SQLException - if a database error happens

For SQL User Defined Types, if a column value is Structured or Distinct, this method behaves the same as a call to: getObject(columnIndex, this.getStatement().getConnection().getTypeMap())
Parameters:
  columnIndex - the index of the column to read an Object containing the value of the column. null if the columnvalue is SQL NULL.
throws:
  SQLException - if a database error happens

The type of the Java object will be determined by the supplied Map to perform the mapping of SQL Struct or Distinct types into Java objects.
Parameters:
  columnIndex - the index of the column to read
Parameters:
  map - a java.util.Map containing a mapping from SQL Type names toJava classes. an Object containing the value of the column. null if the columnvalue is SQL NULL.
throws:
  SQLException - if a database error happens

For SQL User Defined Types, if a column value is Structured or Distinct, this method behaves the same as a call to: getObject(columnIndex, this.getStatement().getConnection().getTypeMap())
Parameters:
  columnName - the name of the column to read an Object containing the value of the column. null if the columnvalue is SQL NULL.
throws:
  SQLException - if a database error happens

The type of the Java object will be determined by the supplied Map to perform the mapping of SQL Struct or Distinct types into Java objects.
Parameters:
  columnName - the name of the column to read
Parameters:
  map - a java.util.Map containing a mapping from SQL Type names toJava classes. an Object containing the value of the column. null if the columnvalue is SQL NULL.
throws:
  SQLException - if a database error happens

The warnings are cleared when a new Row is read from the ResultSet. The warnings returned by this method are only the warnings generated by ResultSet method calls - warnings generated by Statement methods are held by the Statement.

An SQLException is generated if this method is called on a closed ResultSet. an SQLWarning which is the first warning for this ResultSet. nullif there are no warnings.
throws:
  SQLException - if a database error happens

Any InputStreams associated with the current row are closed and any warnings are cleared. true if the updated cursor position is pointing to a valid row,false otherwise (ie when the cursor is after the last row in theResultSet).
throws:
  SQLException - if a database error happens

If any columns in the current row have been updated but the updateRow has not been called, then the updates are lost when this method is called.
throws:
  SQLException - if a database error happens, including if the current row isthe Insert row.