Previous Exercise

Home / Basic / Where

Next Exercise

Control which rows are retrieved

Question

How can you produce a list of facilities that charge a fee to members?
Schema reminder ▼
DB schema

Expected Results

facid name membercost guestcost initialoutlay monthlymaintenance
0 Tennis Court 1 5 25 10000 200
1 Tennis Court 2 5 25 8000 200
4 Massage Room 1 35 80 4000 3000
5 Massage Room 2 35 80 4000 3000
6 Squash Court 3.5 17.5 5000 80

Your Answer Hint Help Save Run Query 


              

            

          

        

      

      

      

      

        

          
Answers and Discussion Show

          
select * from cd.facilities where membercost > 0;          

          

            


The FROM clause is used to build up a set of candidate rows to read results from.  In our examples so far, this set of rows has simply been the contents of a table.  In future we will explore joining, which allows us to create much more interesting candidates.

Once we've built up our set of candidate rows, the WHERE clause allows us to filter for the rows we're interested in - in this case, those with a membercost of more than zero.  As you will see in later exercises, WHERE clauses can have multiple components combined with boolean logic - it's possible to, for instance, search for facilities with a cost greater than 0 and less than 10.  The filtering action of the WHERE clause on the facilities table is illustrated below:











            

          

        

      

      
      

        
Previous Exercise

        

          

            Home / 
            Basic /
              Where 
          

        

        
Next Exercise

      

    

    

      

The WHERE clause allows you to filter the rows that you want to retrieve.
      

      

        

	  
Keyboard shortcuts:

	  
    
	    
  • Alt-h: Show/Hide Help menu
	    
  • Alt-r: Run query
	    
  • Alt-x: Run selected text as query
	    
  • Alt-s: Run query by cursor (delimited by whitespace/semi-colon)
	  

	  

	  
Other hints:

	    
    
	      
  • You can double click on each of the panes of Expected Result/Your answer to quickly resize them.
	      
  • If you have trouble remembering the database schema, you can leave this popup open while you work on your answer.
	      
  • Don't forget to use the hint button if you're stuck!