.TH column "" "" "/rdb Command"
.PC "display columns of a table in any order"
\fBcolumn [ \fIColumn ...\fB ] < \fItableorlist\fR
.PP
.II "column^select"
.II "column^reorder"
.II "select columns"
.II "reorder columns"
The command
.B column
reads
.I tableorlist
and writes a new table (or list) that consists
of each
.IR Column ,
in the order you list them
on the command line.
.PP
If you give a column name that is not one of the columns for
.IR tableorlist ,
.B column
creates a new column with that name, in that
location, and leaves it empty.
This lets you to create new columns.
If you want to compute a column that does not exist, use this
.B column
facility to create it, then use the
.B compute
command to compute it.
However, if you misspell a column name, you will get an empty column.
.PP
If you name no
.I Column
on the command line,
.B column
writes all of
.I tableorlist
to the standard output without change.
.SH Example
Assume that you have an inventory table, as follows:
.DM
Item   Amount    Cost   Value   Description
----   ------   -----   -----   -----------
   1        3    5.00       0   rubber gloves
   2      100    0.50       0   test tubes
   3        5    8.00       0   clamps
   4       23    1.98       0   plates
   5       99    2.45       0   cleaning cloth
   6       89   14.75       0   bunsen burners
   7        5     175       0   scales
.DE
.PP
The command:
.DM
	column Cost Amount Description < inventory
.DE
.PP
produces the following output:
.DM
 Cost   Amount   Description
-----   ------   -----------
 5.00        3   rubber gloves
 0.50      100   test tubes
 8.00        5   clamps
 1.98       23   plates
 2.45       99   cleaning cloth
14.75       89   bunsen burners
  175        5   scales
.DE
.PP
Note that the columns
.B Cost
and
.B Amount
have been reversed.
We only have the columns we asked for and in the order we requested.
.PP
.B column
can also manipulate list-formatted files.
For example, the mailing list called
.I maillist
looks like this:
.DM
Number   1
Name    Ronald McDonald
Company McDonald's
Street  123 Mac Attack
City    Memphis
State   TENN
ZIP     30000
Phone   (111) 222-3333
.sp
Number  2
Name    Chiquita  Banana
Company United Brands
Street  Uno Avenido de la Reforma
City    San Jose
State   Costa Rica
ZIP     123456789
Phone   1234
.DE
.PP
If you want only the names and numbers, type:
.DM
	column Name Phone < maillist
.DE
.PP
This produces the following output:
.DM
Name    Ronald McDonald
Phone   (111) 222-3333
.sp
Name    Chiquita  Banana
Phone   1234
.DE
.SH "Case of Column Names"
.I "(Ruby re-creation only.)"
Column names are case sensitive, as in the original
.BR /rdb .
If the environment variable
.B RDB_ICASE
is set to 1, upper and lower case are ignored when column names are looked up.
An exact match always wins;
if several columns differ only in case, the command stops with an
.I ambiguous
error.
Names that are also
.B awk
reserved words or are followed by
.B (
are never taken for columns.
.SH "Deleting Columns"
.I "(Ruby re-creation only.)"
.DM
column -d Column ... < tableorlist
.DE
.PP
With the option
.BR -d ,
.B column
keeps every column
.I except
those named.
The order of the other columns stays as it is.
It is an error to name a column that does not exist,
or to delete every column.
.DM
subtotal Date Debit Credit < journal | column -d Account Description
.DE
.SH "See Also"
.B
project,
row
.R
.br
COHERENT Lexicon:
.B
awk
.R