UNIX - Replacing variables in sql with matching values from .profile file - shell

Question

I am trying to write a shell which will take an SQL file as input. Example SQL file:
SELECT *
FROM %%DB.TBL_%%TBLEXT
WHERE CITY = '%%CITY'
Now the script should extract all variables, which in this case everything starting with %%. So the output file will be something as below:
%%DB
%%TBLEXT
%%CITY
Now I should be able to extract the matching values from the user's .profile file for these variables and create the SQL file with the proper values.
SELECT *
FROM tempdb.TBL_abc
WHERE CITY = 'Chicago'
As of now I am trying to generate the file1 which will contain all the variables. Below code sample -
sed "s/[(),']//g" "T:/work/shell/sqlfile1.sql" | awk '/%%/{print $NF}' | awk '/%%/{print $NF}' > sqltemp2.sql
takes me till
%%DB.TBL_%%TBLEXT
%%CITY
Can someone help me in getting to file1 listing the variables?

Answer 1

You can use grep and sort to get a list of unique variables, as per the following transcript:
$ echo "SELECT *
FROM %%DB.TBL_%%TBLEXT
WHERE CITY = '%%CITY'" | grep -o '%%[A-Za-z0-9_]*' | sort -u
%%CITY
%%DB
%%TBLEXT
The -o flag to grep instructs it to only print the matching parts of lines rather than the entire line, and also outputs each matching part on a distinct line. Then sort -u just makes sure there are no duplicates.
In terms of the full process, here's a slight modification to a bash script I've used for similar purposes:
# Define all translations.
declare -A xlat
xlat['%%DB']='tempdb'
xlat['%%TBLEXT']='abc'
xlat['%%CITY']='Chicago'
# Check all variables in input file.
okay=1
for key in $(grep -o '%%[A-Za-z0-9_]*' input.sql | sort -u) ; do
if [[ "${xlat[$key]}" == "" ]] ; then
echo "Bad key ($key) in file:"
grep -n "${key}" input.sql | sed 's/^/ /'
okay=0
fi
done
if [[ ${okay} -eq 0 ]] ; then
exit 1
fi
# Process input file doing substitutions. Fairly
# primitive use of sed, must change to use sed -i
# at some point.
# Note we sort keys based on descending length so we
# correctly handle extensions like "NAME" and "NAMESPACE",
# doing the longer ones first makes it work properly.
cp input.sql output.sql
for key in $( (
for key in ${!xlat[#]} ; do
echo ${key}
done
) | awk '{print length($0)":"$0}' | sort -rnu | cut -d':' -f2) ; do
sed "s/${key}/${xlat[$key]}/g" output.sql >output2.sql
mv output2.sql output.sql
done
cat output.sql
It first checks that the input file doesn't contain any keys not found in the translation array. Then it applies sed substitutions to the input file, one per translation, to ensure all keys are substituted with their respective values.
This should be a good start, though there may be some edge cases such as if your keys or values contain characters sed would consider important (like / for example). If that is the case, you'll probably need to escape them such as changing:
xlat['%%UNDEFINED']='0/0'
into:
xlat['%%UNDEFINED']='0\/0'