.TH domain "" "" "/rdb Command"
.PC "Display invalid values in a column"
\fBdomain \fIdomaintable \fB[\fIstring ...\fB] [< \fIone-column-table\fB]\fR
.PP
.II "table^validate"
.II "validate table"
.II "domain table"
The command
.B domain
displays all strings or all rows in
.I one-column-table
that do not match any entry in the
.IR domaintable .
.PP
.B domain
is useful for validating that each item in a column
is legitimate.
First, build a file that consists of a list of all legal values.
In relational theory, these values are called the
.I domain
of the column.
(You can also use the command
.B validate
to validate numbers and short lists of valid strings.)
.PP
To check the domain of a column in a multicolumn table, simply use the
command
.B column
to project the column you want.
.PP
The
.I domaintable
must be sorted because it be searched by the command
.B search
using the binary fast-access method (\fB\-mb\fR).
.B domain
is a shell script, so you can edit it to change its search method,
.SH Example
You might have an order file for cars like this:
.DM
Qty     Model   Colors  Options
------- ------- ------- -------
1       sedan   black   3
1       sedan   green   1
1       sedan   farble  4
3       sedan   red     5
2       convert white   1
1       sedan   purple  2
1       sedan   yellow  4
3       convert blue    2
.DE
.PP
You would also need a sorted file of possible car colors:
.DM
Colors
------
black
blue
carmel
green
purple
red
silver
white
.DE
.PP
Now we can validate the
.B Color
column and see all unacceptable colors:
.DM
	column Colors < orders | domain colors
.DE
.PP
This produces the following output:
.DM
Colors
------
farble
yellow
.DE
.PP
.B domain
complains about
.B farble
and
.B yellow
because neither color is in our domain list.
.PP
You can invoke
.B orders
in the text editor and edit it,
or add those colors to the approved list.
In
.B vi
use the
.B /pattern
command to find all of the
.I patterns
in the orders file.
Another approach is to type something like this:
.DM
	:g/farble/s//purple/g
.DE
.PP
This
.B vi
command will find all instances of
.B farble
and change them to
.BR purple .
.PP
You can also validate strings written on the command line.
For example, the command
.DM
	domain colors red blue purple farble yellow green
.DE
.PP
also prints the output:
.DM
farble
yellow
.DE
.PP
These command-line stings should be quoted if they have
any special characters in them.
They are sought by the command
.BR grep .
If they contain a dollar sign `$',
it should be protected with three backslashes:
this expression is scanned both by the shell and by
.BR grep ,
and it takes three backslashes to get one
backslash through to
.BR grep .
.SH "See Also"
.B
column,
search,
validate,
ve
.R
.br
COHERENT Lexicon:
.B
egrep,
grep,
sort,
uniq
.R
.SO domain