[GRASS-user] Rename multiple sqlite columns at once

[Nikos Alexandris]

On Tue, 2008-11-04 at 10:35 +0100, Paolo Craveri wrote:
> Hello Nikos
> 
> > The command
> > v.db.renamecol map=test_rencol column="AREA","area"
> >
> > does not work. I assume that trying to use 'tr' for example wouldn't
> > help (?). Or am I doing something wrong?
> >
> 
> 
> Try this:
> 
> 
> ==============
> #!/bin/sh
> # # # in this example I use nc_spm_07 dataset
> # # # I created a sqlite mapset
> db.connect driver=sqlite \
> 	database='$GISDBASE/$LOCATION_NAME/$MAPSET/my_sqlitedb.db'
> db.connect -p
> g.copy vect=hospitals,myhospitals --overwrite
> v.db.connect myhospitals -p
> db.columns myhospitals
> #
> # use awk, function: tolower
> # echo "MINNIE" | awk '{print tolower($1)}'
> # minnie
> # ...and function  substr
> #  echo "minnie_tmp"| awk '{print substr($1,1,length($1)-length("_tmp"))}'
> # minnie
> 
> #skip out duplicate column name error
> # (no differences between lower and upper case)
> #
> #
> key_field="cat"
> suffix="_tmp"
> #THIS MAY TAKE A WHILE...
> for field in `db.columns myhospitals`; do
> 	if [ "$field" != "$key_field" ]; then
> 		tmpfield=`echo $field | awk '{print tolower($1)}'`
> 		tmpfield=$tmpfield$suffix
> 		v.db.renamecol map=myhospitals layer=1 column=$field,$tmpfield
> 		lower_field=`echo $tmpfield $suffix| awk '{print
> substr($1,1,length($1)-length($2))}'`
> 		v.db.renamecol map=myhospitals layer=1 column=$tmpfield,$lower_field
> 	fi
> done
> 
> db.columns myhospitals
> =============================
> 
> 
> 
> there are same better and more elegant solutions probably...
> 
> 
> ciao
> 
> 
> Paolo

Ciao Paolo!

Looks like a nice learning-example to me :-)

It works!! But still I get some error/warning from "v.db.renamecol".
Don't know, I changed it a bit... :
----
#!/bin/sh

key_column="cat"
suffix="_tmp"
for column in `db.columns test`; do
        if [ "$column" != "$key_column" ]; then
                tempcolumn=`echo $column | awk '{print tolower($1)}'`
                tempcolumn=$tempcolumn$suffix
                v.db.renamecol map=test layer=1 column=$column,
$tempcolumn
                lower_column=`echo $tempcolumn $suffix| awk '{print
substr($1,1,length($1)-length($2))}'`
                v.db.renamecol map=test layer=1 column=$tempcolumn,
$lower_column
        fi
done
db.columns test
----

The error is:
Sorry <_tmp> is not a valid option

Grazie mille, Nikos