insert_data.sh

#!/bin/bash
# Script to insert data from courses.csv and students.csv into students database
PSQL="psql -X --username=freecodecamp --dbname=students --no-align --tuples-only -c"
echo $($PSQL "truncate students, majors, courses, majors_courses")
cat courses.csv | while IFS="," read MAJOR COURSE
do
  if [[ $MAJOR != major ]]
  then
    # get major_id
    MAJOR_ID=$($PSQL "select major_id from majors where major = '$MAJOR'")

    # if not found
    if [[ -z $MAJOR_ID ]]
    then
      # insert major
      INSERT_MAJOR_RESULT=$($PSQL "insert into majors(major) values('$MAJOR')")
      if [[ $INSERT_MAJOR_RESULT == "INSERT 0 1" ]]
      then
        echo "Inserted into majors, $MAJOR"
      fi

      # get new major_id
      MAJOR_ID=$($PSQL "select major_id from majors where major = '$MAJOR'")
    fi

    # get course_id
    COURSE_ID=$($PSQL "select course_id from courses where course = '$COURSE'")

    # if not found
    if [[ -z $COURSE_ID ]]
    then
      # insert course
      INSERT_COURSE_RESULT=$($PSQL "insert into courses(course) values('$COURSE')")
      if [[ $INSERT_COURSE_RESULT == "INSERT 0 1" ]]
      then
        echo "Inserted into courses, $COURSE"
      fi

      # get new course_id
      COURSE_ID=$($PSQL "select course_id from courses where course = '$COURSE'")
    fi
    # insert into majors_courses
    INSERT_MAJORS_COURSES_RESULT=$($PSQL "insert into majors_courses(major_id, course_id) values($MAJOR_ID, $COURSE_ID)")
    if [[ $INSERT_MAJORS_COURSES_RESULT == "INSERT 0 1" ]]
    then
      echo "Inserted into majors_courses, $MAJOR : $COURSE"
    fi

  fi
done

cat students.csv | while IFS="," read FIRST LAST MAJOR GPA
do
  if [[ $FIRST != "first_name" ]]
  then
  # get major_id
  MAJOR_ID=$($PSQL "select major_id from majors where major = '$MAJOR'")

  # if not found
  if [[ -z $MAJOR_ID ]]
  then
    # set to null
    MAJOR_ID=null
  fi

  # insert student
  INSERT_STUDENT_RESULT=$($PSQL "insert into students(first_name, last_name, major_id, gpa) values('$FIRST', '$LAST', $MAJOR_ID, $GPA)")
  if [[ $INSERT_STUDENT_RESULT == "INSERT 0 1" ]]
  then
    echo "Inserted into students, $FIRST $LAST"
  fi

  fi
done