Exporting SQLite Database to csv file in android

Question

I am trying to export SQLite data to SD card in android as a CSV file on a directory.

So i have tried this method below and apparently it only shows this text printed out:

FIRST TABLE OF THE DATABASE
DATE,ITEM,AMOUNT,CURRENCY

In my DBHelper.java i have defined the function as follows:

public boolean exportDatabase() {
        DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT, Locale.getDefault());

        /**First of all we check if the external storage of the device is available for writing.
         * Remember that the external storage is not necessarily the sd card. Very often it is
         * the device storage.
         */
        String state = Environment.getExternalStorageState();
        if (!Environment.MEDIA_MOUNTED.equals(state)) {
            return false;
        }
        else {
            //We use the Download directory for saving our .csv file.
            File exportDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
            if (!exportDir.exists())
            {
                exportDir.mkdirs();
            }

            File file;
            PrintWriter printWriter = null;
            try
            {
                file = new File(exportDir, "MyCSVFile.csv");
                file.createNewFile();
                printWriter = new PrintWriter(new FileWriter(file));

                /**This is our database connector class that reads the data from the database.
                 * The code of this class is omitted for brevity.
                 */
                SQLiteDatabase db = this.getReadableDatabase(); //open the database for reading

                /**Let's read the first table of the database.
                 * getFirstTable() is a method in our DBCOurDatabaseConnector class which retrieves a Cursor
                 * containing all records of the table (all fields).
                 * The code of this class is omitted for brevity.
                 */
                Cursor curCSV = db.rawQuery("select * from contacts", null);
                //Write the name of the table and the name of the columns (comma separated values) in the .csv file.
                printWriter.println("FIRST TABLE OF THE DATABASE");
                printWriter.println("DATE,ITEM,AMOUNT,CURRENCY");
                while(curCSV.moveToNext())
                {
                    Long date = curCSV.getLong(curCSV.getColumnIndex("date"));
                    String title = curCSV.getString(curCSV.getColumnIndex("title"));
                    Float amount = curCSV.getFloat(curCSV.getColumnIndex("amount"));
                    String description = curCSV.getString(curCSV.getColumnIndex("description"));

                    /**Create the line to write in the .csv file.
                     * We need a String where values are comma separated.
                     * The field date (Long) is formatted in a readable text. The amount field
                     * is converted into String.
                     */
                    String record = df.format(new Date(date)) + "," + title + "," + amount + "," + description;
                    printWriter.println(record); //write the record in the .csv file
                }

                curCSV.close();
                db.close();
            }

            catch(Exception exc) {
                //if there are any exceptions, return false
                return false;
            }
            finally {
                if(printWriter != null) printWriter.close();
            }

            //If there are no errors, return true.
            return true;
        }
    }
}

And my columns are:

 public static final String DATABASE_NAME = "MyDBName.db";
 public static final String CONTACTS_TABLE_NAME = "contacts";
 public static final String CONTACTS_COLUMN_ID = "id";
 public static final String CONTACTS_COLUMN_TITLE = "title";
 public static final String CONTACTS_COLUMN_AMOUNT = "amount";
 public static final String CONTACTS_COLUMN_DESC = "description";

Let me know if you need more code.

Answer 1

Thanks for your suggestions guys which led me to this answer:

private void exportDB() {

        DBHelper dbhelper = new DBHelper(getApplicationContext());
        File exportDir = new File(Environment.getExternalStorageDirectory(), "");
        if (!exportDir.exists())
        {
            exportDir.mkdirs();
        }

        File file = new File(exportDir, "csvname.csv");
        try
        {
            file.createNewFile();
            CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
            SQLiteDatabase db = dbhelper.getReadableDatabase();
            Cursor curCSV = db.rawQuery("SELECT * FROM contacts",null);
            csvWrite.writeNext(curCSV.getColumnNames());
            while(curCSV.moveToNext())
            {
                //Which column you want to exprort
                String arrStr[] ={curCSV.getString(0),curCSV.getString(1), curCSV.getString(2)};
                csvWrite.writeNext(arrStr);
            }
            csvWrite.close();
            curCSV.close();
        }
        catch(Exception sqlEx)
        {
            Log.e("MainActivity", sqlEx.getMessage(), sqlEx);
        }
}

Answer 2

In case someone still stumbles upon this question, I will post my solution, which is slightly more general than the accepted one. You should be able to export all tables in an sqlite database almost by copying the two classes below. Only other changes needed should be related to getting the application context and importing open csv.

Some parts are pretty much copy paste from other stackoverflow threads, but I couldn't find those anymore.

Sqlite exporter:

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

import com.opencsv.CSVWriter;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;


/**
 * Can export an sqlite databse into a csv file.
 *
 * The file has on the top dbVersion and on top of each table data the name of the table
 *
 * Inspired by
 * https://stackoverflow.com/questions/31367270/exporting-sqlite-database-to-csv-file-in-android
 * and some other SO threads as well.
 *
 */
public class SqliteExporter {
    private static final String TAG = SqliteExporter.class.getSimpleName();

    public static final String DB_BACKUP_DB_VERSION_KEY = "dbVersion";
    public static final String DB_BACKUP_TABLE_NAME = "table";

    public static String export(SQLiteDatabase db) throws IOException{
        if( !FileUtils.isExternalStorageWritable() ){
            throw new IOException("Cannot write to external storage");
        }
        File backupDir = FileUtils.createDirIfNotExist(FileUtils.getAppDir() + "/backup");
        String fileName = createBackupFileName();
        File backupFile = new File(backupDir, fileName);
        boolean success = backupFile.createNewFile();
        if(!success){
            throw new IOException("Failed to create the backup file");
        }
        List<String> tables = getTablesOnDataBase(db);
        Log.d(TAG, "Started to fill the backup file in " + backupFile.getAbsolutePath());
        long starTime = System.currentTimeMillis();
        writeCsv(backupFile, db, tables);
        long endTime = System.currentTimeMillis();
        Log.d(TAG, "Creating backup took " + (endTime - starTime) + "ms.");

        return backupFile.getAbsolutePath();
    }

    private static String createBackupFileName(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd_HHmm");
        return "db_backup_" + sdf.format(new Date()) + ".csv";
    }

    /**
     * Get all the table names we have in db
     *
     * @param db
     * @return
     */
    public static List<String> getTablesOnDataBase(SQLiteDatabase db){
        Cursor c = null;
        List<String> tables = new ArrayList<>();
        try{
            c = db.rawQuery("SELECT name FROM sqlite_master WHERE type='table'", null);
            if (c.moveToFirst()) {
                while ( !c.isAfterLast() ) {
                    tables.add(c.getString(0));
                    c.moveToNext();
                }
            }
        }
        catch(Exception throwable){
            Log.e(TAG, "Could not get the table names from db", throwable);
        }
        finally{
            if(c!=null)
                c.close();
        }
        return tables;
    }

    private static void writeCsv(File backupFile, SQLiteDatabase db, List<String> tables){
        CSVWriter csvWrite = null;
        Cursor curCSV = null;
        try {
            csvWrite = new CSVWriter(new FileWriter(backupFile));
            writeSingleValue(csvWrite, DB_BACKUP_DB_VERSION_KEY + "=" + db.getVersion());
            for(String table: tables){
                writeSingleValue(csvWrite, DB_BACKUP_TABLE_NAME + "=" + table);
                curCSV = db.rawQuery("SELECT * FROM " + table,null);
                csvWrite.writeNext(curCSV.getColumnNames());
                while(curCSV.moveToNext()) {
                    int columns = curCSV.getColumnCount();
                    String[] columnArr = new String[columns];
                    for( int i = 0; i < columns; i++){
                        columnArr[i] = curCSV.getString(i);
                    }
                    csvWrite.writeNext(columnArr);
                }
            }
        }
        catch(Exception sqlEx) {
            Log.e(TAG, sqlEx.getMessage(), sqlEx);
        }finally {
            if(csvWrite != null){
                try {
                    csvWrite.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if( curCSV != null ){
                curCSV.close();
            }
        }
    }

    private static void writeSingleValue(CSVWriter writer, String value){
        writer.writeNext(new String[]{value});
    }
}

FileUtils:

public class FileUtils {

    public static String getAppDir(){
        return App.getContext().getExternalFilesDir(null) + "/" + App.getContext().getString(R.string.app_name);
    }

    public static File createDirIfNotExist(String path){
        File dir = new File(path);
        if( !dir.exists() ){
            dir.mkdir();
        }
        return dir;
    }

    /* Checks if external storage is available for read and write */
    public static boolean isExternalStorageWritable() {
        String state = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(state);
    }

    /* Checks if external storage is available to at least read */
    public static boolean isExternalStorageReadable() {
        String state = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(state) ||
                Environment.MEDIA_MOUNTED_READ_ONLY.equals(state);
    }
}

In addition to these two classes, you either need to pass context to the FileUtils, or have some other means of getting the context. In the above code App is just class extending Application for easy access to context.

Also remember to add Opencsv to gradle, i.e.

compile group: 'com.opencsv', name: 'opencsv', version: '4.1'

Then just call the export method of the Sqlite exporter class.

Answer 3

First of all remove this line to have a valid csv formatted document.

printWriter.println("FIRST TABLE OF THE DATABASE");

Second, make sure you have data in your table and check if your query actually returns anything by debugging.