Understanding Indexes
Accessing Rows in a Table
When
you submit a query on a table that does not have an index, PROC SQL
accesses rows sequentially, in the order in which they are stored
in the table. For example, suppose you are working with a table that
contains information about employees. You have written a PROC SQL
query to select the rows in which the value of Name (the first column)
is
Smith. To access the rows that you
want, PROC SQL begins with the first row and reads through all rows
in the table, selecting the rows that satisfy the condition that is
expressed in the WHERE clause.
When you execute a program that retrieves a small ...
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