Displaying All Columns
You already know how to select specific columns for
output by listing them in the SELECT statement. However, for some
tasks, you find it useful to display all columns
of a table concurrently. For example, before you create a complex
query, you might want to see the contents of the table that you are
working with.
Using SELECT *
To display all columns in the order
in which they are stored in a table, use an asterisk (*)
in the SELECT clause. All rows are displayed, by default, unless you
limit or subset them.
The following SELECT
step displays all columns and rows in the table Sasuser.Staffchanges,
which lists all employees in a company who have had changes in their
employment status.
proc sql;
select *
from sasuser.staffchanges;As shown in the output,
the table contains six columns and six rows.
Using the FEEDBACK Option
When
you specify SELECT *, you can also use the FEEDBACK option in the
PROC SQL statement, which writes the expanded list of columns to the
SAS log. For example, the PROC SQL query shown below contains the
FEEDBACK option:
proc sql feedback; select * from sasuser.staffchanges;
This query produces
the following feedback in the SAS log.
202 proc sql feedback; 203 select * 204 from sasuser.staffchanges; NOTE: Statement transforms to: select STAFFCHANGES.EmpID, STAFFCHANGES.LastName, STAFFCHANGES.FirstName, STAFFCHANGES.City, STAFFCHANGES.State, STAFFCHANGES.PhoneNumber from SASUSER.STAFFCHANGES |
The FEEDBACK option
is a debugging tool that lets you see exactly what is being submitted
to the SQL processor. The resulting message in the SAS log not only
expands asterisks (*) into column lists, but it also resolves macro
variables and places parentheses around expressions to show their
order of evaluation.
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