Run query on top of SQLite database and output results to CSV

sqlite_query_to_csv.sh

#!/usr/bin/env bash

# Script accepts 3 parameters
# 1. Query string to execute (in quotes which are opposite of quotes used in the query)
# 2. Database filename where the query will be executed
# 3. Output filename where the query result will be saved

QUERY_STRING=$1
DB_FILE=$2
OUTPUT_FILE=$3

# Check if the first argument is a query string
if [ -z "${QUERY_STRING}" ]; then
    echo "Usage: query_to_csv.sh <query_string> <db_file> <output_file>"
    exit 1
fi

# Check if the second argument is a db file
if [ -z ${DB_FILE} ]; then
    echo "Usage: query_to_csv.sh <query_string> <db_file> <output_file>"
    exit 1
fi

# check if filename ends with .db
if [[ ${DB_FILE} != *.db ]]; then
    echo "Error: ${DB_FILE} is not a db file."
    exit 1
fi

# Check if the db file exists
if [ ! -f ${DB_FILE} ]; then
    echo "Error: ${DB_FILE} does not exist."
    exit 1
fi

# Check if the third argument is an output file
if [ -z ${OUTPUT_FILE} ]; then
    echo "Usage: query_to_csv.sh <query_string> <db_file> <output_file>"
    exit 1
fi

# Check if the sqlite3 command exists
if ! command -v sqlite3 &> /dev/null; then
    echo "Error: sqlite3 command was not found."
    exit 1
fi

# Execute the query and save the result to the output file
sqlite3 ${DB_FILE} <<EOS
.mode csv
.headers on
.once ${OUTPUT_FILE}
${QUERY_STRING}
EOS