Quadcap Embeddable Database

com.quadcap.sql.AggregateCursor Class Reference

Inheritance diagram for com.quadcap.sql.AggregateCursor:

List of all members.

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Detailed Description

Used in conjunction with a GroupByCursor to handle aggregate functions (e.g., SUM, AVG, etc.) with a GROUP BY clause.

Author:

Stan Bailes

Definition at line 56 of file AggregateCursor.java.

Public Member Functions
	AggregateCursor (Session session, Cursor cursor, GroupByCursor gcursor, Vector aggregates) throws SQLException
void	resetAggregates () throws SQLException
void	updateAggregates (Cursor c) throws SQLException
Row	getRow () throws SQLException
	Derived class implements this function to return the current cursor row.
void	updateRow (Row row) throws SQLException
	Replace the current cursor row with the specified row.
void	deleteRow () throws SQLException
	Delete the current cursor row.
void	beforeFirst () throws SQLException
	Position the cursor before the first row.
boolean	next () throws SQLException
	This routine returns the next element of an aggregate cursor, i.e., one which uses SUM, COUNT, AVG, MAX, or MIN.
boolean	isWritable (int col) throws SQLException
	Return true if the specified column is writable.
long	size ()
	We don't know the size.
void	close () throws SQLException
	Close the cursor and free up any resources (including closing the cursor's transaction if that is feasible) used by the cursor.
Package Attributes
GroupByCursor	gcursor = null
Vector	aggregates = null
Row	row = null
int	currentRowNum = 0
boolean	first = true
boolean	isItemCursor = false
ItemsCursor	itemsCursor = null
Cursor	baseCursor = null

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Constructor & Destructor Documentation

com.quadcap.sql.AggregateCursor.AggregateCursor (  Session  session, Cursor  cursor, GroupByCursor  gcursor, Vector  aggregates )  throws SQLException

Definition at line 66 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.aggregates, com.quadcap.sql.AggregateCursor.baseCursor, com.quadcap.sql.AggregateCursor.gcursor, com.quadcap.sql.ItemsCursor.getBaseCursor(), com.quadcap.sql.AggregateCursor.isItemCursor, and com.quadcap.sql.AggregateCursor.itemsCursor.

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Member Function Documentation

void com.quadcap.sql.AggregateCursor.beforeFirst (   )  throws SQLException [virtual]

Position the cursor before the first row. Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 117 of file AggregateCursor.java. References com.quadcap.sql.Cursor.beforeFirst(), and com.quadcap.sql.AggregateCursor.first.

void com.quadcap.sql.AggregateCursor.close (   )  throws SQLException [virtual]

Close the cursor and free up any resources (including closing the cursor's transaction if that is feasible) used by the cursor. Exceptions: SQLException  may be thrown Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 173 of file AggregateCursor.java. References com.quadcap.sql.Cursor.close(), and com.quadcap.sql.AggregateCursor.resetAggregates().

void com.quadcap.sql.AggregateCursor.deleteRow (   )  throws SQLException [virtual]

Delete the current cursor row. Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 112 of file AggregateCursor.java.

Row com.quadcap.sql.AggregateCursor.getRow (   )  throws SQLException [virtual]

Derived class implements this function to return the current cursor row. Implementation required. Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 103 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.row.

boolean com.quadcap.sql.AggregateCursor.isWritable (  int  col  )  throws SQLException [virtual]

Return true if the specified column is writable. Parameters: column  the (one-based) column number Exceptions: SQLException  may be thrown Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 164 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.isWritable(). Referenced by com.quadcap.sql.AggregateCursor.isWritable().

boolean com.quadcap.sql.AggregateCursor.next (   )  throws SQLException [virtual]

This routine returns the next element of an aggregate cursor, i.e., one which uses SUM, COUNT, AVG, MAX, or MIN. If GROUP BY is not specified, 'next()' simply fetches all of the underlying rows, updating the aggregate expressions after each row. If there is a GROUP BY clause, we have to keep track of when a new group starts using our associated group-by cursor. Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 132 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.baseCursor, com.quadcap.sql.AggregateCursor.first, com.quadcap.sql.AggregateCursor.gcursor, com.quadcap.sql.ItemsCursor.getEmptyAggregate(), com.quadcap.sql.Cursor.getRow(), com.quadcap.sql.AggregateCursor.isItemCursor, com.quadcap.sql.AggregateCursor.itemsCursor, com.quadcap.sql.GroupByCursor.lastRowOfGroup(), com.quadcap.sql.Cursor.next(), com.quadcap.sql.AggregateCursor.resetAggregates(), and com.quadcap.sql.AggregateCursor.row.

void com.quadcap.sql.AggregateCursor.resetAggregates (   )  throws SQLException

Definition at line 81 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.aggregates. Referenced by com.quadcap.sql.AggregateCursor.close(), and com.quadcap.sql.AggregateCursor.next().

long com.quadcap.sql.AggregateCursor.size (   )

We don't know the size. Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 171 of file AggregateCursor.java.

void com.quadcap.sql.AggregateCursor.updateAggregates (  Cursor  c  )  throws SQLException

Definition at line 93 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.aggregates, com.quadcap.sql.AggregateExpression.updateAggregate(), and com.quadcap.sql.AggregateCursor.updateAggregates(). Referenced by com.quadcap.sql.AggregateCursor.updateAggregates().

void com.quadcap.sql.AggregateCursor.updateRow (  Row  row  )  throws SQLException [virtual]

Replace the current cursor row with the specified row. Reimplemented from com.quadcap.sql.FilterCursor. Definition at line 107 of file AggregateCursor.java. References com.quadcap.sql.AggregateCursor.updateRow(). Referenced by com.quadcap.sql.AggregateCursor.updateRow().

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Member Data Documentation

Vector com.quadcap.sql.AggregateCursor.aggregates = null [package]

Definition at line 58 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.AggregateCursor(), com.quadcap.sql.AggregateCursor.resetAggregates(), and com.quadcap.sql.AggregateCursor.updateAggregates().

Cursor com.quadcap.sql.AggregateCursor.baseCursor = null [package]

Definition at line 64 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.AggregateCursor(), and com.quadcap.sql.AggregateCursor.next().

int com.quadcap.sql.AggregateCursor.currentRowNum = 0 [package]

Definition at line 60 of file AggregateCursor.java.

boolean com.quadcap.sql.AggregateCursor.first = true [package]

Definition at line 61 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.beforeFirst(), and com.quadcap.sql.AggregateCursor.next().

GroupByCursor com.quadcap.sql.AggregateCursor.gcursor = null [package]

Definition at line 57 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.AggregateCursor(), and com.quadcap.sql.AggregateCursor.next().

boolean com.quadcap.sql.AggregateCursor.isItemCursor = false [package]

Definition at line 62 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.AggregateCursor(), and com.quadcap.sql.AggregateCursor.next().

ItemsCursor com.quadcap.sql.AggregateCursor.itemsCursor = null [package]

Definition at line 63 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.AggregateCursor(), and com.quadcap.sql.AggregateCursor.next().

Row com.quadcap.sql.AggregateCursor.row = null [package]

Definition at line 59 of file AggregateCursor.java. Referenced by com.quadcap.sql.AggregateCursor.getRow(), and com.quadcap.sql.AggregateCursor.next().