Convert output to arrays then extract values to loop

I would use a simple bash while read and keep adding elements into the array with the += syntax:

outputres=()
while read -r _ a b _; do
  outputres+=("$a $b")
done < file

Doing so, with your input file, I got:

$ echo "${outputres[@]}"     #print all elements
db1 ADM_DAT db2 SYSAUX
$ echo "${outputres[0]}"     #print first one
db1 ADM_DAT
$ echo "${outputres[1]}"     #print second one
db2 SYSAUX

Since you want to use both values separatedly, it may be better to use an associative array:

$ declare -A array=()
$ while read -r _ a b _; do array[$a]=$b; done < file

And then you can loop through the values with:

$ for key in ${!array[@]}; do     echo "array[$key] = ${array[$key]}"; done
array[db2] = SYSAUX
array[db1] = ADM_DAT

See a basic example of utilization of these arrays:

#!/bin/bash
declare -A array=([key1]='value1' [key2]='value2')

for key in ${!array[@]}; do
    echo "array[$key] = ${array[$key]}"
done

echo ${array[key1]}
echo ${array[key2]}

So maybe this can solve your problem: loop through the file with columns, fetch the 2nd and 3rd and use them twice: firstly the $a to perform a grep in file and then as parameters to cmd_command:

while read -r _ a b _
do
    echo "cmd_command $(awk -v patt="$a" '$0~patt {print $1}' file) $a, $b"
done < columns_file

For a sample file file:

$ cat file
hello this is db1
and this is another db2

I got this output (note I am just echoing):

$ while read -r _ a b _; do echo "cmd_command $(awk -v patt="$a" '$0~patt {print $1}' file) $a, $b"; done < a
cmd_command hello db1, ADM_DAT
cmd_command and db2, SYSAUX