Android sqlite how to check if a record exists

I would like to check whether a record exists or not.

Here is what I've tried:

MainActivity.class

    public void onTextChanged(CharSequence s, int start, int before, int count) {

	    System.out.println("Ontext changed " + new String(s.toString()));
	    strDocumentFrom = s.toString();	    	
	    
	    if(s.toString().isEmpty()){
	    	    		
	    } else {
	    	
	    	 try{
	    		 strTransactionDate = dbHelper.getTransactionDateByDocumentNumber(strDocumentFrom);
		    	 //strTotalAmount = dbHelper.getTotalAmountByDocumentNumber(strDocumentFrom);
		    	 //strVan = dbHelper.getVanByDocumentNumber(strDocumentFrom);
		    	 
		    	 
		    	 //etTransactionDate.setText(strTransactionDate);
		    	 //etTotalAmount.setText(strTotalAmount);
		    	 //Log.d("Van", "" + strVan);
		    	 //etVan.setText(strVan);
		    	 
	    	 } catch (SQLiteException e) {
	    		 e.printStackTrace();
	    		 Toast.makeText(ReceivingStocksHeader.this, 
	    				 "Document number does not exist.", Toast.LENGTH_SHORT).show();
	    	 }
		
	    }

DBHelper.class

            // TODO DISPLAYING RECORDS TO TRANSRCVHEADER
        public String getTransactionDateByDocumentNumber(String strDocumentNumber){
        	String[] columns = new String[]{KEY_TRANSACTIONDATE};
        	
        	Cursor c = myDataBase.query(TBL_INTRANS, 
        			columns, null, 
        			null, null, null, null, null);
        	
        	if(c != null){
        		c.moveToFirst();
        		String date = c.getString(0);
        		return date;
        	} else {
        		Log.d("Error", "No record exists");
        	}
        	
        	
        	return null;
        }

But it doesn't get it to the catch block to display the toast.

What am I doing wrong in here?

public static boolean CheckIsDataAlreadyInDBorNot(String TableName,
		String dbfield, String fieldValue) {
	SQLiteDatabase sqldb = EGLifeStyleApplication.sqLiteDatabase;
	String Query = "Select * from " + TableName + " where " + dbfield + " = " + fieldValue;
	Cursor cursor = sqldb.rawQuery(Query, null);
        if(cursor.getCount() <= 0){
            cursor.close();
	        return false;
        }
    cursor.close();
    return true;
}

I hope this is useful to you... This function returns true if record already exists in db. Otherwise returns false.

These are all good answers, however many forget to close the cursor and database. If you don't close the cursor or database you may run in to memory leaks.

Additionally:
You can get an error when searching by String that contains non alpha/numeric characters. For example: "1a5f9ea3-ec4b-406b-a567-e6927640db40". Those dashes (-) will cause an unrecognized token error. You can overcome this by putting the string in an array. So make it a habit to query like this:

public boolean hasObject(String id) {
    SQLiteDatabase db = getWritableDatabase();
    String selectString = "SELECT * FROM " + _TABLE + " WHERE " + _ID + " =?";
    
    // Add the String you are searching by here. 
    // Put it in an array to avoid an unrecognized token error 
    Cursor cursor = db.rawQuery(selectString, new String[] {id}); 
   
    boolean hasObject = false;
    if(cursor.moveToFirst()){
        hasObject = true;
        
        //region if you had multiple records to check for, use this region. 
        
        int count = 0;
        while(cursor.moveToNext()){
          count++;
        }
        //here, count is records found
        Log.d(TAG, String.format("%d records found", count));
       
        //endregion

    } 

    cursor.close();          // Dont forget to close your cursor
    db.close();              //AND your Database!
    return hasObject;
}

you can also see this:

if (cursor.moveToFirst()) {
// record exists
} else {
// record not found
}

OR

You just check Cursor not null after that why you check count not 0.

So, that you try this...

DBHelper.getReadableDatabase();

Cursor mCursor = db.rawQuery("SELECT * FROM " + DATABASE_TABLE + " WHERE    yourKey=? AND yourKey1=?", new String[]{keyValue,keyvalue1});

if (mCursor != null)
{
            return true;
/* record exist */
 }
else
{
        return false;
/* record not exist */
}

Raw queries are more vulnerable to SQL Injection. I will suggest using query() method instead.

public boolean Exists(String searchItem) {

    String[] columns = { COLUMN_NAME };
    String selection = COLUMN_NAME + " =?";
    String[] selectionArgs = { searchItem };
    String limit = "1";

    Cursor cursor = db.query(TABLE_NAME, columns, selection, selectionArgs, null, null, null, limit);
    boolean exists = (cursor.getCount() > 0);
    cursor.close();
    return exists;
}

Source: here

You can use SELECT EXISTS command and execute it for a cursor using a rawQuery, from the documentation > The EXISTS operator always evaluates to one of the integer values 0 > and 1. If executing the SELECT statement specified as the right-hand > operand of the EXISTS operator would return one or more rows, then the > EXISTS operator evaluates to 1. If executing the SELECT would return > no rows at all, then the EXISTS operator evaluates to 0.

SELECT EXISTS with LIMIT 1 is much faster.

Query Ex: SELECT EXISTS (SELECT * FROM table_name WHERE column='value' LIMIT 1);

Code Ex:

public boolean columnExists(String value) {
    String sql = "SELECT EXISTS (SELECT * FROM table_name WHERE column='"+value+"' LIMIT 1)";
    Cursor cursor = database.rawQuery(sql, null);
    cursor.moveToFirst();

    // cursor.getInt(0) is 1 if column with value exists
    if (cursor.getInt(0) == 1) { 
        cursor.close();
        return true;
    } else {
        cursor.close();
        return false;
    }
}

I have tried all methods mentioned in this page, but only below method worked well for me.

Cursor c=db.rawQuery("SELECT * FROM user WHERE idno='"+txtID.getText()+"'", null);
if(c.moveToFirst())
{
 showMessage("Error", "Record exist");
}
else
{
 // Inserting record
}

One thing the top voted answer did not mention was that you need single quotes, 'like this', around your search value if it is a text value like so:

public boolean checkIfMyTitleExists(String title) {
    String Query = "Select * from " + TABLE_NAME + " where " + COL1 + " = " + "'" + title + "'";
    Cursor cursor = database.rawQuery(Query, null);
    if(cursor.getCount() <= 0){
        cursor.close();
        return false;
    }
    cursor.close();

    return true;
}

Otherwise, you will get a "SQL(query) error or missing database" error like I did without the single quotes around the title field.

If it is a numeric value, it does not need single quotes.

Refer to this SQL post for more details

SQLiteDatabase sqldb = MyProvider.db;
String Query = "Select * from " + TABLE_NAME ;
Cursor cursor = sqldb.rawQuery(Query, null);
cursor.moveToLast(); //if you not place this cursor.getCount() always give same integer (1) or current position of cursor.

if(cursor.getCount()<=0){
	Log.v("tag","if 1 "+cursor.getCount());
	return false;
}
Log.v("tag","2 else  "+cursor.getCount());

return true;

if you not use cursor.moveToLast();

cursor.getCount() always give same integer (1) or current position of cursor.

Code :

private String[] allPushColumns = { MySQLiteHelper.COLUMN_PUSH_ID,
        MySQLiteHelper.COLUMN_PUSH_TITLE, MySQLiteHelper.COLUMN_PUSH_CONTENT, MySQLiteHelper.COLUMN_PUSH_TIME,
        MySQLiteHelper.COLUMN_PUSH_TYPE, MySQLiteHelper.COLUMN_PUSH_MSG_ID}; 
 
public boolean checkUniqueId(String msg_id){
 
    Cursor cursor = database.query(MySQLiteHelper.TABLE_PUSH,
            allPushColumns, MySQLiteHelper.COLUMN_PUSH_MSG_ID + "=?", new String [] { msg_id }, null, null, MySQLiteHelper.COLUMN_PUSH_ID +" DESC");

    if(cursor.getCount() <= 0){
        return false;
    }
    return true;
}

Here's a simple solution based on a combination of what dipali and Piyush Gupta posted:

  public boolean dbHasData(String searchTable, String searchColumn, String searchKey) {
    String query = "Select * from " + searchTable + " where " + searchColumn + " = ?";
    return getReadableDatabase().rawQuery(query, new String[]{searchKey}).moveToFirst();
  }

because of possible data leaks best solution via cursor:

 Cursor cursor = null;
    try {
          cursor =  .... some query (raw or not your choice)
          return cursor.moveToNext();
    } finally {
        if (cursor != null) {
            cursor.close();
        }
    }

1. From API KITKAT u can use resources try()

   try (cursor = ...some query)

2. if u query against VARCHAR TYPE use '...' eg. COLUMN_NAME='string_to_search'

3. dont use moveToFirst() is used when you need to start iterating from beggining

4. avoid getCount() is expensive - it iterates over many records to count them. It doesn't return a stored variable. There may be some caching on a second call, but the first call doesn't know the answer until it is counted.

Try to use cursor.isNull method. Example:

song.isFavorite = cursor.isNull(cursor.getColumnIndex("favorite"));

You can use like this:

String Query = "Select * from " + TABLE_NAME + " where " + Cust_id + " = " + cust_no;

Cursor cursorr = db.rawQuery(Query, null);
if(cursor.getCount() <= 0){
cursorr.close();
}
cursor.close();

private boolean checkDataExistOrNot(String columnName, String value) {
    SQLiteDatabase sqLiteDatabase = getReadableDatabase();
    String query = "SELECT * FROM" + TABLE_NAME + " WHERE " + columnName + " = " + value;
    Cursor cursor = sqLiteDatabase.rawQuery(query, null);
    if (cursor.getCount() <= 0) {
        cursor.close();
        return false;  // return false if value not exists in database
    }
    cursor.close();
    return true;  // return true if value exists in database
}