Develop Reference

android sql how to handle large Query 200000 lines database?

i use this code to give suggestions to the user when typing. but one query takes lot of time. is there a way to speed up?
String cnql = "SELECT DISTINCT sinhala FROM jgd WHERE sinhala LIKE '"+gg+"%' LIMIT 0,4";
Cursor cg=cn.rawQuery(cnql, null);

You can create a virtual table for full text searching on Android which provides a very quick way to retrieve matching strings. However, it does require you set up and maintain a separate FTS virtual table and populate it with the strings you want to search. As its focus is full text search, it does not support a 'starts with' type of operator, although you can gg + "*" to search for words prefixed with your search query.

How to write contains query in SQLite fts3 fulltext search

I want to make fulltext search in my index table which is sqlite fts3.
For example;
the data set is { "David Luiz", "David Villa", "Diego Costa", "Diego Ribas", "Diego Milito","Gabriel Milito", }
When I type "vid i" I want to get {"David Luiz", "David Villa"}
In documentation of SQLite I found this
http://www.sqlite.org/fts3.html#section_3
but it contains just startswith query.
my query is:
SELECT *FROM Table WHERE Table MATCH "*vid* *i*"
I dont know it is possible or not. If it is possible to make search in sqlite fts3, any help will be appreciated

The FTS index is optimized for word searches, and supports word prefix searches.
There is no index that can help with searches inside words.
You have to use LIKE '%vid%' (which scans the entire table).

Change your query from
SELECT * FROM Table WHERE Table MATCH "*vid* *i*"
To
SELECT * FROM SOME_TABLE WHERE some_column LIKE '%vid%'

SQLite Fts select query

I am making a dictionary of over 20,000 words in it. So, to make it work faster when search data, i am using fts3 table to do it.
my select query:
Cursor c=db.rawQuery("Select * from data where Word MATCH '"+word+"*'", null);
Using this query, it will show all the word that contain 'word' , but what i want is to get only the word that contain the beginning of the searching word.
Mean that i want it work like this query:
Cursor c=db.rawQuery("Select * from data where Word like '"+word+"%'", null);
Ex: I have : apple, app, and, book, bad, cat, car.
when I type 'a': i want it to show only: apple, app, and
What can i solve with this?

table(_id primary key not null autoincrement, word text)
FTS table does not use the above attributes. It ignores data type. It does not auto increment columns other than the hidden rowid column. "_id" will not act as a primary key here. Please verify that you are implementing an FTS table
https://www.sqlite.org/fts3.html
a datatype name may be optionally specified for each column. This is
pure syntactic sugar, the supplied typenames are not used by FTS or
the SQLite core for any purpose. The same applies to any constraints
specified along with an FTS column name - they are parsed but not used
or recorded by the system in any way.
As for your original question, match "abc*" already searches from the beginning of the word. For instance match "man*" will not match "woman".

FTS supports searching for the beginning of a string with ^:
SELECT * FROM FtsTable WHERE Word MATCH '^word*'
However, the full-text search index is designed to find words inside larger texts.
If your Word column contains only a single word, your query is more efficient if you use LIKE 'a%' and rely on a normal index.
To allow an index to be used with LIKE, the table column must have TEXT affinity, and the index must be declared as COLLATE NOCASE (because LIKE is not case sensitive):
CREATE TABLE data (
...
Word TEXT,
...
);
CREATE INDEX data_Word_index ON data(Word COLLATE NOCASE);
If you were to use GLOB instead, the index would have to be case sensitive (the default).
You can use EXPLAIN QUERY PLAN to check whether the query uses the index:
sqlite> EXPLAIN QUERY PLAN SELECT * FROM data WHERE Word LIKE 'a%';
0|0|0|SEARCH TABLE data USING INDEX data_Word_index (Word>? AND Word<?)

Search data from sqlite3 database in android

I have a Sqlite3 database in android, with data are sentences like: "good afternoon" or "have a nice day", now I want to have a search box, to search between them, I use something like this :
Cursor cursor = sqliteDB.rawQuery("SELECT id FROM category WHERE sentences LIKE '"+ s.toString().toLowerCase()+ "%' LIMIT 10", null);
But it only show "good afternoon" as result if user start searching with first "g" or "go" or "goo" or etc, how can I retrieve "good afternoon" as results, if user search like "a" or "af" or "afternoon".
I mean I want to show "good afternoon" result, if user search from middle of a data in sqlite3 db, not only if user searches from beginning.
thanks!

Just put the percent sign in front of your query string: LIKE '%afternoon%'. However, your approach has two flaws:
It is susceptible to SQL injection attacks because you just insert unfiltered user input into your SQL query string. Use the query parameter syntax instead by re-writing your query as follows:
SELECT id FROM category WHERE sentences LIKE ? LIMIT 10. Add the user input string as selection argument to your query method call
It will be dead slow the bigger your database grows because LIKE queries are not optimized for quick string matching and lookups.
In order to solve number 2 you should use SQLite's FTS3 extension which greatly speeds up any text-related searches. Instead of LIKE you would be using the MATCH operator that uses a different query syntax:
SELECT id FROM category WHERE sentences MATCH 'afternoon' LIMIT 10
As you can see the MATCH operator does not need percent signs. It just tries to find any occurrence of a word in the whole text that is being searched (in your case the sentences column). Read through the documentation of FTS3 I've linked to. The MATCH query syntax provides some more pretty handy and powerful options for finding text in your database table which are pretty similar to early search engine query syntax such as:
MATCH 'afternoon OR evening'
The only (minor) downside to the FTS3 extension is that it blows up the database file size by creating additional search index tables and meta-data. But I think it's well worth it for this use case.

Best way to search sqlite database

In my application ,am work with a large database.Nearly 75000 records present in a table(totally 6 tables are there).i want to get a data from three different table at a time.i completed that.but the search process was slow.how can i optimise the searching process?

You might want to consider using the full-text search engine and issuing SELECT...MATCH queries instead. Note that you need to enable the FTS engine (it's disabled by default) and create virtual tables instead of regular tables. You can read more about it here.

Without being able to see the table structure (or query) the first thing I'd suggest is adding some indexes to the tables.
Lets say you have a few tables like:
Author
id
last_name
first_name
Subject
id
name
Book
id
title
author_id
subject_id
and you're wanting to get all the information about each of the books that an author with last_name="Smith" and first_name="John" wrote. Your query might look something like this:
SELECT * FROM Book b
LEFT JOIN Subject s
ON s.id=b.subject_id
LEFT JOIN Author a
ON a.id=b.author_id
WHERE a.last_name='Smith'
AND a.first_name='John';
There you'd want the last_name column in the Author table to have an index (and maybe first_name too).