Develop Reference

Queries in SQLite

I have the following insert statement in my app which work.
Before the insert I want to first check the database if the value name does not exist in the name column.
If it does not exists I want to continue with the insert, else display an error message.
How do I incorporate it into my existing statement below?
public void insert(HashMap<String, String> queryValues){
SQLiteDatabase database = this.getWritableDatabase();
ContentValues values = new ContentValues();
Cursor c = database.query("SELECT * FROM user_details where" + "name=?", new String[] {values.put("name") });
if (c.getCount() > 0) {
// don't do it
return;
}
else {
values.put("name", queryValues.get("name"));
values.put("age", queryValues.get("age"));
database.insert("user", null, values);
}
database.close();
}

The correct way to do this is to add a unique constraint on the name field, and then use insertWithOnConflict() with a last argument of CONFLICT_FAIL. That's actually the default behavior. Your insert will fail if it would otherwise cause a constraint violation (insert() will return -1).
If you don't want to do that, there's no magic. Query your DB for a row with the given name field. If you are returned >0 rows, don't perform the insert.
Cursor c = db.query(..., "name=?", new String[] {theName}, ...);
if (c.getCount > 0) {
// don't do it
return;
}

Sqlite Insert or Update

I wanted to update my existing table with new values but some of them are fresh. I have written code for updating the table, but how can I do both operations(update & insert) simultaneously.

Just use replace() method in SQLiteDatabase. Its simply insert a new row if no row with same key is not exists in database. Otherwise it replaces the existing row.. Its simple than other ways.. For more info refer the documentation..
http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html

Try something like this:
String username="xyzName";
Cursor cur_user = my_db.rawQuery("SELECT _id from user_info where user_name ='"
+ username + "'", null);
if (cur_user.getCount() > 0) {
// User exists. Update information in database.
ContentValues cvUserInfo = new ContentValues();
cvUserInfo.put("status", status_id);
String whereClause = "user_name = '" + username + "'";
try {
my_db.update("user_info", cvUserInfo, whereClause, null);
} catch (Exception e) {
e.printStackTrace();
}
} else {
// Insert the information in database.
ContentValues cvUserInfo = new ContentValues();
cvUserInfo.put("status", status_id);
cvUserInfo.put("user_name", username);
my_db.insert("user_info", null, cvUserInfo);
}
You will need to have one column except id, on which you can check. I had user name as a unique column to check for existing record.
Hope this helps.

Android SqlLite update last inserted row

This is what i am using for insert:
public long insert(String content, Date startAt, Date endAt) {
if (content == null || startAt == null) {
return 0;
}
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_CONTENT, content);
contentValues.put(KEY_START_AT, startAt.getTime());
if (endAt == null) {
contentValues.putNull(KEY_END_AT);
} else {
contentValues.put(KEY_END_AT, endAt.getTime());
}
return sqLiteDatabase.insert(TABLE_NAME, null, contentValues);
}
now i want to create update method which will update last inserted row. How can i get last inserted row?

If you have an id attribute that works as a primary key, you can do a raw database query on SqlLite.
Cursor cc = this.mDb.rawQuery("SELECT *" + " FROM " + "<Your DATABASE_NAME> " +
"ORDER BY id " + "DESC LIMIT 1", null);
return cc;
Here,
1. It returns a cursor.
2. mDb is a SQLiteDatabase class instance.
3. ORDER BY id allows the query to sort by id number. As I said, if you have an id as primary key in your table, your latest entry will have the maximum id number.
4. DESC allows to sort by descending order.
5. LIMIT 1 allows to return only 1 row.
6. Always be careful when writing raw queries, white spaces inside the query can be a lot of pain when you do not handle them carefully.
For further queries you can see this tutorial. And obviously Divya's answer is also a good one.

You can use a cursor to retrieve rows and say :
cursor.moveToLast();
OR
cursor.moveToPosition(cursor.getCount() - 1);

When you insert a row in to your table the insert query returns the key of the last inserted row. You can now use this key to update this row.
for example
int newInsertedKey = sqLiteDatabase.insert(TABLE_NAME, null, contentValues);
update table_name set column_name = 'Change 2' where columnID = newInsertedKey
An efficient method would be to avoid anymore database queries to get the last updated row.

Maybe he should use something like this
public long getLastId() {
Cursor c = mDb.query(currentTableName, new String[] { "MAX(_id)" },
null, null, null, null, null, null);
try{
c.moveToFirst();
long id = c.getLong(0);
return id;
}catch(Exception e){
return 0;
}
}
where _id is column by which you identify rows

Before inserting a record in the database to validate that there is

Before inserting a record in the database to validate that there is, for example I have a table that has two fields, table fields VA with Customer, First, I want to validate the field if there is no customer registration and if there insert
That i want to do in android using Sqlite

String sql = "SELECT * FROM TABLE WHERE id = '" + id + "'";
Cursor data = database.rawQuery(sql, null);
After this check by following code
if (cursor.moveToFirst()) {
// record exists
} else {
// record not found
}

Look at SQLite constraints. This really isn't Android-specific; it's a feature of SQLite.

Try this, it works for me.
String[] args = { myDataToCheck };
c = ourDatabase.query(DATABASE_TABLE, columns,
myColumnToCheck + "=?", args, null, null, null);
if (c.getCount() == 0) {
// doesn't exists
}else{
//exists
}

You have 2 possibilities :
1)make a select to check if there is the same key in database, then insert or update.
2)make directly an update. update will return the number of row updated, if the number is 0, so you can do an insert.

Fastest way to search through strings stored in sqlite database

I have large number of strings, approximately 15,000 that I stored in a SQLite database using the following code:
void addKey(String key, String value, String table) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_KEY, key); // Contact Name
values.put(KEY_VALUE, value); // Contact Phone
// Inserting Row
db.insert(table, null, values);
db.close(); // Closing database connection
}
And then i search through that database using the following method in order to pick out any strings that match the key im looking for:
public String searchKeyString(String key, String table){
String rtn = "";
Log.d("searchKeyString",table);
// Select All Query
String selectQuery = "SELECT * FROM " + table;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Log.d("searchKeyString","searching");
if(cursor.getString(1).equals(key))
rtn = rtn + "," + cursor.getString(2);
} while (cursor.moveToNext());
}
cursor.close();
db.close();
Log.d("searchKeyString","finish search");
return rtn;
}
The goal is to do this in real time as the user is typing on the keep board so response time is key and the way it stands now it takes over a second to run through the search.
I considered reading all of the items into an array list initially and sorting through that which might be faster, but i thought an array list of that size might cause memory issues. What is the best way to search through these entries in my database?

A couple of things you can do...
Change the return to a StringBuilder until the end.
Only use a readable version of the database (that's probably not making much difference though)
Do not get a new instance of the database every time, keep it opened until you don't need it anymore
Query for only what you need with the "WHERE" argument in the SQL query.
See the code below with some changes:
// move this somewhere else in your Activity or such
SQLiteDatabase db = this.getReadableDatabase();
public String searchKeyString(String key, String table){
StringBuilder rtn = new StringBuilder();
Log.d("searchKeyString",table);
// Select All Query
String selectQuery = "SELECT * FROM " + table + " WHERE KEY_KEY=?";
Cursor cursor = db.rawQuery(selectQuery, new String[] {key});
// you can change it to
// db.rawQuery("SELECT * FROM "+table+" WHERE KEY_KEY LIKE ?", new String[] {key+"%"});
// if you want to get everything starting with that key value
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Log.d("searchKeyString","searching");
rtn.append(",").append(cursor.getString(2));
} while (cursor.moveToNext());
}
cursor.close();
Log.d("searchKeyString","finish search");
return rtn.toString();
}
Note even if you want this to happen in "real-time" for the user, you will still need to move this to a separate Thread or ASyncTask or you are going to run into problems....

You should consider using SELECT * FROM your-table LIMIT 50, for example. And you can put two buttons "Back", "Next" on your view. If every page has max 50 items, the user is at page 1, and he taps "Next", then you can use this query:
SELECT * FROM your-table LIMIT 50 OFFSET 50
If your table contains most of text-data, and you want to integrate search deeply into your app, consider using virtual table with FTS.

Let sqlite do the hard lifting.
First off, add an index to the field you're searching for, if you don't have one already. Secondly, don't do a SELECT all with manual table scan, but rather use a query in the form
SELECT column_value
FROM my_table
WHERE column_key LIKE "ABC%"
This returns the least amount of data, and the sql engine uses the index.

i dunno about better but maybe it'd be faster to make queries for the selected strings one by one.
public String searchKeyString(String key, String table){
String rtn = "";
Log.d("searchKeyString",table);
// Select All Query
String selectQuery = "SELECT * FROM " + table + "WHERE column_1 = " + key;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
rtn = rtn + "," + cursor.getString(2);
}
cursor.close();
db.close();
Log.d("searchKeyString","finish search");
return rtn;
}
EDIT:
Well i dunno how those custom keyboard apps do it, but those AutoCompleteTextViews are hooked up to adapters. you could just as easily make a cursorAdapter and hook your auto-complete view to it.
http://www.outofwhatbox.com/blog/2010/11/android-autocompletetextview-sqlite-and-dependent-fields/
http://www.opgenorth.net/blog/2011/09/06/using-autocompletetextview-and-simplecursoradapter-2/