Android Studio search existing sqlite db - sqlite

Question

So im developing an app and I want the user to search for a food item in my database and then to be returned with a list view of all food names that match the search criteria. I already have my slqite database created and added to the assets folder. The database is called foodDatabase.db
I have created the Database Helper like so:
package com.example.codebind.databasedemo;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
/**
* Created by tom on 15/03/2018.
*/
public class FoodDatabaseHelper extends SQLiteOpenHelper{
public static final String DATABASE_NAME = "FoodDatabase.db";
public static final String TABLE_NAME = "dataset";
public static final String COL_1 = "ID";
public static final String COL_2 = "Food";
public static final String COL_3 = "Description";
public static final String COL_4 = "Protein";
public static final String COL_5 = "Fat";
public static final String COL_6 = "Carbohydrate";
public static final String COL_7 = "Energy";
public static final String COL_8 = "Starch";
public static final String COL_9 = "Sugar";
public static final String COL_10 = "Cholesterol";
public FoodDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
}
#Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL("create table " + TABLE_NAME +" (ID INTEGER
PRIMARY KEY AUTOINCREMENT,FOOD TEXT,DESCRIPTION TEXT,PROTEIN BLOB,FAT
BLOB,CARBOHYDRATE BLOB,ENERGY BLOB,STARCH BLOB,SUGAR BLOB,CHOLESTEROL BLOB)
");
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " +TABLE_NAME);
onCreate(sqLiteDatabase);
}
}
and currently my MainActivity.java is clean. I haven't touched it yet.
I'm asking for guidance on how to add a listener so that when the user enters a food name the app will return all foods from the foodDatabase.db that meets the search query.
Thanks

Answer 1

The basis of your search will be a query based upon the FOOD column (I believe).
e.g. SELECT * FROM dataset WHERE FOOD LIKE '%your_food%'
For example assume that your database has data such as (note only food and id columns have been populated with data) :-
Then the query SELECT * FROM dataset WHERE FOOD LIKE '%mash%' would result in :-
i.e. Foods with an id of 2 and 3 contain the food mash
You could run this query using the SQLiteDatabase query method. The query method returns a Cursor with the extracted data. So a method in your DatabaseHelper could be :-
public Cursor getFoodsWithProvidedFood(String provided_food) {
return this.getWritableDatabase().query(
TABLE_NAME,
null,
COL_2 + " LIKE '%" + provided_food + "%' ",
null,
null,
null,
null
);
}
Converting this into a complete but very basic App you could have :-
The Database Helper - FoodDatabaseHelper.java
public class FoodDatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "FoodDatabase.db";
public static final String TABLE_NAME = "dataset";
public static final String COL_1 = "ID";
public static final String COL_2 = "Food";
public static final String COL_3 = "Description";
public static final String COL_4 = "Protein";
public static final String COL_5 = "Fat";
public static final String COL_6 = "Carbohydrate";
public static final String COL_7 = "Energy";
public static final String COL_8 = "Starch";
public static final String COL_9 = "Sugar";
public static final String COL_10 = "Cholesterol";
SQLiteDatabase sqLiteDatabase; //<<<< Added
public FoodDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
sqLiteDatabase = this.getWritableDatabase(); //<<<< Amended
}
//#Override
public void onNotRecommendedCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL("create table " + TABLE_NAME +
" (ID INTEGER PRIMARY KEY AUTOINCREMENT," +
"FOOD TEXT," +
"DESCRIPTION TEXT," +
"PROTEIN BLOB," +
"FAT BLOB," +
"CARBOHYDRATE BLOB," +
"ENERGY BLOB," +
"STARCH BLOB," +
"SUGAR BLOB," +
"CHOLESTEROL BLOB)");
}
#Override
public void onCreate(SQLiteDatabase db) {
String crtsql = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME +
"(" +
COL_1 + " INTEGER PRIMARY KEY, " +
COL_2 + " TEXT, " +
COL_3 + " TEXT, " +
COL_4 + " BLOB, " +
COL_5 + " BLOB, " +
COL_6 + " BLOB, " +
COL_7 + " BLOB, " +
COL_8 + " BLOB, " +
COL_9 + " BLOB, " +
COL_10 + " BLOB " +
")";
db.execSQL(crtsql);
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " +TABLE_NAME);
onCreate(sqLiteDatabase);
}
public void insertFood(
String food,
String description,
byte[] protien,
byte[] fat,
byte[] carbohydrate,
byte[] energy,
byte[] starch,
byte[] sugar,
byte[] cholesterol) {
ContentValues cv = new ContentValues();
cv.put(COL_2,food);
cv.put(COL_3,description);
cv.put(COL_4,protien);
cv.put(COL_5,fat);
cv.put(COL_6,carbohydrate);
cv.put(COL_7,energy);
cv.put(COL_8,starch);
cv.put(COL_9,sugar);
cv.put(COL_10,cholesterol);
SQLiteDatabase db = this.getWritableDatabase();
db.insert(TABLE_NAME,null,cv);
}
public Cursor getFoodsWithProvidedFood(String provided_food) {
return this.getWritableDatabase().query(
TABLE_NAME,
null,
COL_2 + " LIKE '%" + provided_food + "%' ",
null,
null,
null,
null
);
}
}
Notes
It will likely cause fewer issue if you have just one place where you define table and column names.
hence the changed onCreate
although column names in SQLite are case-insensitive the Cursor's getColumnIndex method (as used in the main activity) is case-sensitive (IMO a bug).
AUTOINCREMENT doesn't do what it implies, rather INTEGER PRIMARY KEY itself makes a column one that increments adding AUTOINCREMENT is a special case that ensures that the id is greater at the expense of overheads. Hence AUTOINCREMENT has been removed.
Two additional methods have been added
insertFood to insert(add) data to the dataset table.
getFoodsWithProvidedFood as described above.
The Activity - MainActivity.java
public class MainActivity extends AppCompatActivity {
FoodDatabaseHelper foodDBHlpr;
Cursor mCsr;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
foodDBHlpr = new FoodDatabaseHelper(this);
byte[] dummy = new byte[]{0,1,2,3,4,5,6,7,8,9};
// Add some data oif none exists
if (DatabaseUtils.queryNumEntries(foodDBHlpr.getWritableDatabase(),FoodDatabaseHelper.TABLE_NAME) < 1) {
foodDBHlpr.insertFood("Fish and Chips", "The English Seaside meal",
dummy, dummy, dummy, dummy, dummy, dummy, dummy);
foodDBHlpr.insertFood("Bangers and Mash", "Yummy!!",
dummy, dummy, dummy, dummy, dummy, dummy, dummy);
foodDBHlpr.insertFood("Mashed Potatoe", "Boring",
dummy, dummy, dummy, dummy, dummy, dummy, dummy);
}
// get a Cursor with the extracted foods
mCsr = foodDBHlpr.getFoodsWithProvidedFood("Mash");
// Loop Through the Cursor
while (mCsr.moveToNext()) {
Log.d("FOODFOUND","You found the food called - " + mCsr.getString(mCsr.getColumnIndex(FoodDatabaseHelper.COL_2)));
}
if (mCsr.getCount() < 1) {
Log.d("FOODFOUND","No foods found that match the search criteria.");
}
mCsr.close(); //<<<< Should always close Cursors when done with them
}
}
Result in the Log :-
03-15 21:48:21.170 1702-1702/foodsdb.so49307874_foodsdb D/FOODFOUND: You found the food called - Bangers and Mash
03-15 21:48:21.170 1702-1702/foodsdb.so49307874_foodsdb D/FOODFOUND: You found the food called - Mashed Potatoe