|
SELECT Verb Options
The SELECT verb has some powerful and useful options that
can make life easier when attempting to gather data for analysis. One of these
is the SAMPLE option. When you are developing RETRIEVE reports, it is often
useful to look at sample data to determine such things as field length, column
header descriptions, etc. You can use the SAMPLE option with the SELECT verb to
gather a representative sample of any file. Below is an example of the use of
this option:
>SELECT
SOLI SAMPLE 5
5 records selected to list 0.
>
Another useful feature of RETRIEVE is the ability to compare
the contents of different fields of the same record. Below is an example of
this, where we are seeking records where the total ordered quantity EQ the
total open quantity (Note: UniData users
are required to use the lower case version of the verb – invoking the native
UniData behavior -- to make this work):
>list
SOLI WITH F11 EQ
F39 F11 F39
5 records selected to list 0.
08:10:01 JAN 08 2003 1
SOLI...... Total Ordered Quantity Total Open Quantity
187998*2
10 10
201157*1
10 10
201157*2
10 10
201157*3
3 3
201157*4
10 10
183984*2
2 2
Enter <New line> to continue...
Using SAMPLE AND SAMPLED
On UniData and UniVerse, you can also use SAMPLE with the
LIST or SORT verbs to limit the volume of data reported on. The syntax is the same on both RDBMS systems:
SAMPLE [n]
The first n records from the file are selected and listed, e.g.
>LIST PARTS DESC SAMPLE 5
SAMPLED provides slightly different behavior
SAMPLED [n]
Selects every nth record from the file, e.g.
>LIST PARTS DESC SAMPLED 5
Note the SORT verb with the SAMPLE (or SAMPLED) command works the
same as always, that is, it selects the records, builds a sorted list, and
then displays the data.
|
Our technical tips are here to help you find new or
easier ways to solve some of your technical
challenges or to show you a new technique. We hope
you find them useful.
