element.sh

#!/bin/bash

if [[ -z $1 ]]
then
  echo "Please provide an element as an argument."
else
  PSQL="psql --username=freecodecamp --dbname=periodic_table -t --no-align -c"

  # Check if argument is a number
  if [[ $1 =~ ^[0-9]+$ ]]
  then
    CONDITION="atomic_number = $1"
  else
    CONDITION="symbol = '$1' OR name = '$1'"
  fi

  ELEMENT_NAME=$($PSQL "SELECT name FROM elements WHERE $CONDITION")
  ATOMIC_NUMBER=$($PSQL "SELECT atomic_number FROM elements WHERE $CONDITION")
  ELEMENT_SYMBOL=$($PSQL "SELECT symbol FROM elements WHERE $CONDITION")

  if [[ -z $ATOMIC_NUMBER ]]
  then
    echo "I could not find that element in the database."
  else
    PROPERTIES=$($PSQL "SELECT atomic_mass, melting_point_celsius, boiling_point_celsius, type_id FROM properties WHERE atomic_number = $ATOMIC_NUMBER")

    echo "$PROPERTIES" | while IFS="|" read ATOMIC_MASS MELTING_POINT BOILING_POINT TYPE
    do
      ELEMENT_TYPE=$($PSQL "SELECT type FROM types WHERE type_id = $TYPE")
      echo "The element with atomic number $ATOMIC_NUMBER is $ELEMENT_NAME ($ELEMENT_SYMBOL). It's a $ELEMENT_TYPE, with a mass of $ATOMIC_MASS amu. $ELEMENT_NAME has a melting point of $MELTING_POINT celsius and a boiling point of $BOILING_POINT celsius."
    done
  fi
fi