//Desciption: Joins the instance of R1 and the instance of R2
//Precondition: Files must exist and be in the appropriate folders. Attributes must be valid.
public string Join(string R1FileName, string R2FileName, string R1Attr, string R2Attr)
{
//local vars
OuterTable outerTableForJoin = null;
InnerTable innerTableForJoin = null;
string joinResult;
//iterate through R1 instances
foreach (OuterTable outerTable in outerTables)
{
if (outerTable.relationName == R1FileName)
{
outerTableForJoin = outerTable;
break;
}
}
//iterate through R2 instances
foreach (InnerTable innerTable in innerTables)
{
if (innerTable.relationName == R2FileName)
{
innerTableForJoin = innerTable;
break;
}
}
//do join
joinResult = outerTableForJoin.HashJoin(innerTableForJoin, R1Attr, R2Attr);
//return result
return(joinResult);
}
//Description: Gets selectivity of a join
public double SelectivityOfJoin(string R1FileName, string R2FileName, string R1Attr, string R2Attr)
{
//local vars
string joinResult;
String[] linesOfJoinResult;
double selectivityOfJoin;
OuterTable outerTableOfJoin = null;
InnerTable innerTableOfJoin = null;
//find OuterTable object for R1FileName
foreach (OuterTable outerTable in outerTables)
{
if (outerTable.relationName == R1FileName)
{
outerTableOfJoin = outerTable;
break;
}
}
//find InnerTable object for R2FileName
foreach (InnerTable innerTable in innerTables)
{
if (innerTable.relationName == R2FileName)
{
innerTableOfJoin = innerTable;
break;
}
}
//do join
joinResult = Join(R1FileName, R2FileName, R1Attr, R2Attr);
//split joinResult into its separate lines
linesOfJoinResult = joinResult.Split('\n');
//calcualte selectivity of join
selectivityOfJoin = ((double)(linesOfJoinResult.Length - 1)) / (outerTableOfJoin.numRows * innerTableOfJoin.numRows);
return(selectivityOfJoin);
}
private void ClickEvent(object sender, RoutedEventArgs e)
{
//local vars
string joinResult;
String[] linesOfJoinResult;
double selectivityOfJoin;
//if one of the combo boxes has nothing selected
if ((R1AttributeComboBox.SelectedIndex == -1) || (R2AttributeComboBox.SelectedIndex == -1) ||
(R1InstanceComboBox.SelectedIndex == -1) || (R2InstanceComboBox.SelectedIndex == -1))
{
MessageBox.Show("You must make a selection for each Drop Down Box. Try again.");
return;
}
//Remove all items from R1ListBox
while (R1ListBox.Items.Count != 0)
{
R1ListBox.Items.RemoveAt(0);
}
//remove all items from R2ListBox
while (R2ListBox.Items.Count != 0)
{
R2ListBox.Items.RemoveAt(0);
}
//remove all items from JoinResultListBox
while (JoinResultListBox.Items.Count != 0)
{
JoinResultListBox.Items.RemoveAt(0);
}
//find selected R1 instance
foreach (OuterTable outerTable in tableManager.outerTables)
{
if (outerTable.relationName == (string)R1InstanceComboBox.Items.GetItemAt(R1InstanceComboBox.SelectedIndex))
{
selectedOuterTable = outerTable;
}
}
//find selected R2 instance
foreach (InnerTable innerTable in tableManager.innerTables)
{
if (innerTable.relationName == (string)R2InstanceComboBox.Items.GetItemAt(R2InstanceComboBox.SelectedIndex))
{
selectedInnerTable = innerTable;
}
}
//get selected R1 attribute
selectedR1Attribute = (string)((ComboBoxItem)R1AttributeComboBox.Items.GetItemAt(R1AttributeComboBox.SelectedIndex)).Content;
//get selected R2 attribute
selectedR2Attribute = (string)((ComboBoxItem)R2AttributeComboBox.Items.GetItemAt(R2AttributeComboBox.SelectedIndex)).Content;
//fill list box for R1
foreach (String line in selectedOuterTable.outerTableFile)
{
R1ListBox.Items.Add(line);
}
//fill list box for R2
foreach (String line in selectedInnerTable.innerTableFile)
{
R2ListBox.Items.Add(line);
}
//do join
joinResult = tableManager.Join(selectedOuterTable.relationName, selectedInnerTable.relationName, selectedR1Attribute, selectedR2Attribute);
//split join result into the separate lines
linesOfJoinResult = joinResult.Split('\n');
//remove '\r' from the end of each string
for (int i = 0; i < linesOfJoinResult.Length - 1; ++i)
{
linesOfJoinResult[i] = linesOfJoinResult[i].Substring(0, linesOfJoinResult[i].Length - 1);
}
//put join result in list box
foreach (string line in linesOfJoinResult)
{
JoinResultListBox.Items.Add(line);
}
//calculate selectivity
selectivityOfJoin = tableManager.SelectivityOfJoin(selectedOuterTable.relationName, selectedInnerTable.relationName, selectedR1Attribute, selectedR2Attribute);
//set selectivity label
SelectivityOfJoinLabel.Text = "Selectivity of Join: " + Convert.ToString(selectivityOfJoin);
}
