SQL Injection Attacks and Defense - 2009

GROUP BY Statement
References • Chapter 10 421
You typically would use the GROUP BY statement when performing an aggregate function
such as SUM against a column in a table. For example, consider that you would like to
perform a query against the following Orders table (Table 10.2) to calculate the total cost
for customer Anthony Anteater.
Table 10.2 Orders Table
ID Customer Product Cost
1 Gary Smith Scooter 7000
2 Anthony Anteater Porsche 911 65000
3 Simon Sez Citron C2 1500
4 Anthony Anteater Oil 10
5 Anthony Anteater Super Alarm 100
The following statement will automatically group orders received from user Anthony
Anteater and then perform a SUM operation against the Cost column:
SELECT customer,SUM(cost) FROM orders WHERE customer = 'Anthony Anteater'
GROUP BY customer
ORDER BY Clause
You use the ORDER BY clause to sort the results of a SELECT statement by a specific
column; it accepts either a column name or a number as a mandatory parameter. It is possible
to add the keyword ASC or DESC to sort the results in an ascending or descending order,
respectively. The following SQL statement will select the cost and product columns from
the orders table and sort the results by the cost column in descending order:
SELECT cost, product FROM orders ORDER BY cost DESC
Limiting the Result Set
When performing SQL injection attacks you will often need to limit the number of table
rows returned by your injected query (e.g., when extracting data via error messages).
The syntax for selecting a specific row from a table varies among database platforms. Table 10.3
details the SQL syntax for selecting the first and fifth rows from the tblUsers table.