Eliminating Duplicate Rows
When working with SELECT statements, you’ll inevitably come across result sets with duplicate rows. There is no cause for alarm if you see such a result set. Use the DISTINCT keyword in your SELECT statement, and the result set will be free and clear of all duplicate rows. Figure 4-9 shows the syntax diagram for the DISTINCT keyword.
Figure 4-9. The syntax for the DISTINCT keyword
As the diagram illustrates, DISTINCT is an optional keyword that precedes the list of columns specified in the SELECT clause. The DISTINCT keyword asks your database system to evaluate the values of all the columns as a single unit on a ...
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