java.lang.Object
- org.apache.derby.impl.sql.execute.NoRowsResultSetImpl
- - org.apache.derby.impl.sql.execute.MergeResultSet

All Implemented Interfaces:

ResultSet
```
class MergeResultSet
extends NoRowsResultSetImpl
```
INSERT/UPDATE/DELETE a target table based on how it outer joins with a driving table. For a description of how Derby processes the MERGE statement, see the header comment on MergeNode.

Field Summary

Fields
Modifier and Type	Field	Description
`private MergeConstantAction`	`_constants`
`private NoPutResultSet`	`_drivingLeftJoin`
`private int`	`_numOpens`
`private ExecRow`	`_row`
`private long`	`_rowCount`
`private BackingStoreHashtable`	`_subjectRowIDs`
`private TemporaryRowHolderImpl[]`	`_thenRows`

Fields inherited from class org.apache.derby.impl.sql.execute.NoRowsResultSetImpl
activation, beginExecutionTime, beginTime, endExecutionTime, endTime, lcc

Fields inherited from interface org.apache.derby.iapi.sql.ResultSet
CURRENT_RESULTSET_ONLY, ENTIRE_RESULTSET_TREE, ISAFTERLAST, ISBEFOREFIRST, ISFIRST, ISLAST

Constructor Summary

Constructors
Constructor Description

MergeResultSet(NoPutResultSet drivingLeftJoin, Activation activation)
Construct from a driving left join and an Activation.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private void`	`addSubjectRow(SQLRef subjectRowID)`	Add another subject row id to the evolving hashtable of affected target rows.
`void`	`cleanUp()`	Tells the system to clean up on an error.
`void`	`close()`	Clean up resources and call close on data members.
`(package private) boolean`	`collectAffectedRows()`	Loop through the rows in the driving left join.
`private void`	`createSubjectRowIDhashtable()`	Create a BackingStoreHashtable to hold the ids of subject rows.
`void`	`finish()`	Tells the system that there will be no more access to any database information via this result set; in particular, no more calls to open().
`long`	`modifiedRowCount()`	Returns zero.
`void`	`open()`	Needs to be called before the result set will do anything.
`(package private) void`	`setup()`	Set up the result set for use.

Methods inherited from class org.apache.derby.impl.sql.execute.NoRowsResultSetImpl
addWarning, checkRowPosition, clearCurrentRow, close, doesCommit, evaluateGenerationClauses, getAbsoluteRow, getActivation, getAutoGeneratedKeysResultset, getBeginExecutionTimestamp, getCurrentTimeMillis, getCursorName, getEndExecutionTimestamp, getExecuteTime, getFirstRow, getLastRow, getNextRow, getPreviousRow, getQueryPlanText, getRelativeRow, getResultDescription, getRowNumber, getSubqueryTrackingArray, getTimeSpent, getWarnings, isClosed, returnsRows, setAfterLastRow, setBeforeFirstRow, toXML

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - _drivingLeftJoin
```
private NoPutResultSet _drivingLeftJoin
```
  - _constants
```
private MergeConstantAction _constants
```
  - _row
```
private ExecRow _row
```
  - _rowCount
```
private long _rowCount
```
  - _thenRows
```
private TemporaryRowHolderImpl[] _thenRows
```
  - _subjectRowIDs
```
private BackingStoreHashtable _subjectRowIDs
```
  - _numOpens
```
private int _numOpens
```
- Constructor Detail
  - MergeResultSet
```
MergeResultSet(NoPutResultSet drivingLeftJoin,
               Activation activation)
        throws StandardException
```
    Construct from a driving left join and an Activation.
    
    Throws:
    
    StandardException
- Method Detail
  - modifiedRowCount
```
public final long modifiedRowCount()
```
    Description copied from class: NoRowsResultSetImpl
    
    Returns zero.
    
    Specified by:
    
    modifiedRowCount in interface ResultSet
    
    Overrides:
    
    modifiedRowCount in class NoRowsResultSetImpl
    
    Returns:
    
    The number of rows affect by the statement, so far.
  - open
```
public void open()
          throws StandardException
```
    Description copied from interface: ResultSet
    
    Needs to be called before the result set will do anything. Need to call before getNextRow(), or for a result set that doesn't return rows, this is the call that will cause all the work to be done.
    
    Throws:
    
    StandardException - Thrown on failure
  - setup
```
void setup()
    throws StandardException
```
    Description copied from class: NoRowsResultSetImpl
    
    Set up the result set for use. Should always be called from open().
    
    Overrides:
    
    setup in class NoRowsResultSetImpl
    
    Throws:
    
    StandardException - thrown on error
  - close
```
public void close()
           throws StandardException
```
    Clean up resources and call close on data members.
    
    Throws:
    
    StandardException - Thrown on error.
  - cleanUp
```
public void cleanUp()
             throws StandardException
```
    Description copied from interface: ResultSet
    
    Tells the system to clean up on an error.
    
    Throws:
    
    StandardException - Thrown on error.
  - finish
```
public void finish()
            throws StandardException
```
    Description copied from interface: ResultSet
    
    Tells the system that there will be no more access to any database information via this result set; in particular, no more calls to open(). Will close the result set if it is not already closed.
    
    Specified by:
    
    finish in interface ResultSet
    
    Overrides:
    
    finish in class NoRowsResultSetImpl
    
    Throws:
    
    StandardException - on error
  - collectAffectedRows
```
boolean collectAffectedRows()
                     throws StandardException
```
    Loop through the rows in the driving left join.
    
    Throws:
    
    StandardException
  - addSubjectRow
```
private void addSubjectRow(SQLRef subjectRowID)
                    throws StandardException
```
    Add another subject row id to the evolving hashtable of affected target rows. The concept of a subject row is defined by the 2011 SQL Standard, part 2, section 14.12 (merge statement), general rule 6. A row in the target table is a subject row if it joins to the source table on the main search condition and if the joined row satisfies the matching refinement condition for some WHEN MATCHED clause. A row in the target table may only be a subject row once. That is, a given target row may only qualify for UPDATE or DELETE processing once. If it qualifies for more than one UPDATE or DELETE action, then the Standard requires us to raise a cardinality violation.
    
    Parameters:
    
    subjectRowID - The location of the subject row.
    
    Throws:
    
    StandardException - A cardinality exception is thrown if we've already added this subject row.
  - createSubjectRowIDhashtable
```
private void createSubjectRowIDhashtable()
                                  throws StandardException
```
    Create a BackingStoreHashtable to hold the ids of subject rows.
    
    Throws:
    
    StandardException

Class MergeResultSet

Field Summary

Fields inherited from class org.apache.derby.impl.sql.execute.NoRowsResultSetImpl

Fields inherited from interface org.apache.derby.iapi.sql.ResultSet

Constructor Summary

Method Summary

Methods inherited from class org.apache.derby.impl.sql.execute.NoRowsResultSetImpl

Methods inherited from class java.lang.Object

Field Detail

_drivingLeftJoin

_constants

_row

_rowCount

_thenRows

_subjectRowIDs

_numOpens

Constructor Detail

MergeResultSet

Method Detail

modifiedRowCount

open

setup

close

cleanUp

finish

collectAffectedRows

addSubjectRow

createSubjectRowIDhashtable