Self join - Revision history

Taichikitty: As stated, Question 7 result should only give one line for each unique pair of company, num; thus added DISTINCT.

2013-03-31T20:40:12Z

As stated, Question 7 result should only give one line for each unique pair of company, num; thus added DISTINCT.

2013-02-21T05:19:56Z

2013-02-21T05:17:58Z

2013-02-13T11:31:46Z

2013-02-13T10:35:12Z

2012-09-30T09:38:27Z

2012-09-30T09:29:14Z

just added the table structures

2012-08-15T11:59:34Z

2012-08-14T16:22:19Z

2012-07-27T01:40:39Z

@@ Line 126: / Line 126: @@
 <source lang='sql' class='ans'>
-SELECT R1.company, R1.num
+SELECT DISTINCT R1.company, R1.num
    FROM route R1, route R2
    WHERE R1.num=R2.num AND R1.company=R2.company

@@ Line 164: / Line 164: @@
 <div class='qu'>
-Show it is possible to get from Sighthill to Craiglockhart by changing lanes twice. Stupid!
+Try to show it is possible to get from Sighthill to Craiglockhart by changing lanes twice.
 <source lang='sql' class='def'>
 </source>

@@ Line 164: / Line 164: @@
 <div class='qu'>
-Show it is possible to get from Sighthill to Craiglockhart by changing lanes twice.
+Show it is possible to get from Sighthill to Craiglockhart by changing lanes twice. Stupid!
 <source lang='sql' class='def'>
 </source>

@@ Line 164: / Line 164: @@
 <div class='qu'>
-Show it is possible to get from Sighthill to Craiglockhart.
+Show it is possible to get from Sighthill to Craiglockhart by changing lanes twice.
 <source lang='sql' class='def'>
 </source>

@@ Line 79: / Line 79: @@
 <div class='qu'>
-Execute the self join shown and observe that b.stop gives all the places you can get to from Craiglockhart.
+Execute the self join shown and observe that b.stop gives all the places you can get to from Craiglockhart, without changing routes.
 Change the query so that it shows the services from Craiglockhart to London Road.
 <source lang='sql' class='def'>

@@ Line 2: / Line 2: @@
 <p>[[Edinburgh_Buses. |Details of the database]] Looking at the data</p>
   stops('''id''', name)
-  route('''num''','''company''','''pros''', ''stop'')
+  route('''num''','''company''','''pos''', ''stop'')
   <div class='schema'></div>
@@ Line 10: / Line 10: @@
 <tr><td>id</td><td>num</td></tr>
 <tr><td>name</td><td>company</td></tr>
-<tr><td></td><td>pros</td></tr>
+<tr><td></td><td>pos</td></tr>
 <tr><td></td><td>stop</td></tr>
 <tr><td></td><td></td></tr>

@@ Line 170: / Line 170: @@
 <div>
 <div class="lsclear">Clear your results</div>
-[[Self join Quiz]]
+<p><div class="quizlink">[[Self join Quiz]]</div></p>
 </div>

← Older revision		Revision as of 01:40, 27 July 2012
Line 169:		Line 169:

	<div class="lsclear">Clear your results</div>		<div class="lsclear">Clear your results</div>
−

	[[Self join Quiz]]		[[Self join Quiz]]