TweetFollow Us on Twitter

Life with SQLite

Volume Number: 21 (2005)
Issue Number: 6
Column Tag: Programming

Tips From Big Nerd Ranch

Life with SQLite

by Aaron Hillegass, Chris Campbell, Marquis Logan

With Tiger, Apple has started using SQLite in many ways. Most notably, SQLite is the recommended store for Core Data applications.

What is SQLite?

A database server, for example Oracle or PostgreSQL, is a daemon that responds to requests from client applications. The clients make requests of the server using Structured Query Language (SQL) via some client library. The server takes care of the security, concurrency, and distribution issues. The server stores tables of data that can be indexed for quick random access.

    SQLite is not a database server.

SQLite is an open-source C library written by Dr. Richard Hipp. It creates a file that holds tables of data that can be indexed for quick random access. You read and write to this file using SQL. The main advantage of SQLite over archiving is that the data can be read and updated incrementally. (An archive is read in one big piece, and must be completely rewritten if the resulting object graph is edited.) The performance and scalability of SQLite is excellent -- Dr. Hipp's mother has every right to be very proud of him.

You can learn all about SQLite at the website:

http://www.sqlite.org/

Looking at SQLite files

SQLite comes with a command-line tool called sqlite3. The tool is installed automatically with Tiger. Using sqlite3, you can interactively inspect and edit any SQLite file. If you are curious about how Core Data structures the file, sqlite3 is a great way to explore it. sqlite3 has several non-SQL commands that start with a dot. .schema will show you the create statements for all the tables and indices in the file:

% sqlite3 test.eventsq 
sqlite> .schema
CREATE TABLE ZLOCATION 
    (Z_ENT INTEGER, Z_PK INTEGER PRIMARY KEY, Z_OPT INTEGER, 
    ZDETAILDESCRIPTION VARCHAR, ZNAME VARCHAR );
CREATE TABLE ZPERSON 
    (Z_ENT INTEGER, Z_PK INTEGER PRIMARY KEY, Z_OPT INTEGER, 
    ZNOTES VARCHAR, ZFIRSTNAME VARCHAR, ZLASTNAME VARCHAR );
...
CREATE INDEX ZEVENT_ZOCCASION_INDEX ON ZEVENT (ZOCCASION);
sqlite>  select * from zperson;
 5 | 1 | 1 | Bride  | Laura | Smith
 5 | 2 | 1 | Groom  | Craig | Adams

Watching the SQL executed by Core Data

This tip requires that you use some API that Apple has not yet exposed, and I would not use it in a shipping application. It is, however, a great way to understand exactly what Core Data is doing with SQLite. To log every SQL command sent to SQLite, execute the following code early in your application:

Class privateClass;
privateClass = NSClassFromString(@"NSSQLConnection");
// The compiler will give a warning here
[privateClass setDebugDefault:YES];

Using SQLite in non-Core Data applications

There are a couple of reasons why you might want to write an application that works with SQLite files, but doesn't use Core Data:

1) Backwards compatibility: Core Data is only available on Tiger.

2) Performance: While Core Data is very clever about which rows to fetch from a sqlite file, it fetches all the columns for those rows. If you know that you only need one or two columns, you may get a significant performance win from writing an explicit SELECT statement.

QuickLite is an Objective-C wrapper for SQLite by Tito Ciuro. It is an open source framework, and you can download it at:

http://www.webbotech.com/

One of the QuickLite example programs is SQLiteManagerX, a very useful Cocoa application for browsing and editing SQLite files.


Figure 1. SQLiteManagerX browsing a SQLite file

SQLite is not a database server

Before we end this, let us remind you that SQLite is not a database server. If more than one user is going to be accessing the data, you need a database server to take care of security, distribution, and concurrency issues. (There are, for example, many stories of companies trying to use Microsoft Access as a networked datastore. Most of the stories end with tears and a massive rewrite.) If your data is accessed by only one user, SQLite is an elegant and efficient solution.


Aaron Hillegass, Chris Campbell, Marquis Logan

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Six fantastic ways to spend National Vid...
As if anyone needed an excuse to play games today, I am about to give you one: it is National Video Games Day. A day for us to play games, like we no doubt do every day. Let’s not look a gift horse in the mouth. Instead, feast your eyes on this... | Read more »
Old School RuneScape players turn out in...
The sheer leap in technological advancements in our lifetime has been mind-blowing. We went from Commodore 64s to VR glasses in what feels like a heartbeat, but more importantly, the internet. It can be a dark mess, but it also brought hundreds of... | Read more »
Today's Best Mobile Game Discounts...
Every day, we pick out a curated list of the best mobile discounts on the App Store and post them here. This list won't be comprehensive, but it every game on it is recommended. Feel free to check out the coverage we did on them in the links below... | Read more »
Nintendo and The Pokémon Company's...
Unless you have been living under a rock, you know that Nintendo has been locked in an epic battle with Pocketpair, creator of the obvious Pokémon rip-off Palworld. Nintendo often resorts to legal retaliation at the drop of a hat, but it seems this... | Read more »
Apple exclusive mobile games don’t make...
If you are a gamer on phones, no doubt you have been as distressed as I am on one huge sticking point: exclusivity. For years, Xbox and PlayStation have done battle, and before this was the Sega Genesis and the Nintendo NES. On console, it makes... | Read more »
Regionally exclusive events make no sens...
Last week, over on our sister site AppSpy, I babbled excitedly about the Pokémon GO Safari Days event. You can get nine Eevees with an explorer hat per day. Or, can you? Specifically, you, reader. Do you have the time or funds to possibly fly for... | Read more »
As Jon Bellamy defends his choice to can...
Back in March, Jagex announced the appointment of a new CEO, Jon Bellamy. Mr Bellamy then decided to almost immediately paint a huge target on his back by cancelling the Runescapes Pride event. This led to widespread condemnation about his perceived... | Read more »
Marvel Contest of Champions adds two mor...
When I saw the latest two Marvel Contest of Champions characters, I scoffed. Mr Knight and Silver Samurai, thought I, they are running out of good choices. Then I realised no, I was being far too cynical. This is one of the things that games do best... | Read more »
Grass is green, and water is wet: Pokémo...
It must be a day that ends in Y, because Pokémon Trading Card Game Pocket has kicked off its Zoroark Drop Event. Here you can get a promo version of another card, and look forward to the next Wonder Pick Event and the next Mass Outbreak that will be... | Read more »
Enter the Gungeon review
It took me a minute to get around to reviewing this game for a couple of very good reasons. The first is that Enter the Gungeon's style of roguelike bullet-hell action is teetering on the edge of being straight-up malicious, which made getting... | Read more »

Price Scanner via MacPrices.net

Take $150 off every Apple 11-inch M3 iPad Air
Amazon is offering a $150 discount on 11-inch M3 WiFi iPad Airs right now. Shipping is free: – 11″ 128GB M3 WiFi iPad Air: $449, $150 off – 11″ 256GB M3 WiFi iPad Air: $549, $150 off – 11″ 512GB M3... Read more
Apple iPad minis back on sale for $100 off MS...
Amazon is offering $100 discounts (up to 20% off) on Apple’s newest 2024 WiFi iPad minis, each with free shipping. These are the lowest prices available for new minis among the Apple retailers we... Read more
Apple’s 16-inch M4 Max MacBook Pros are on sa...
Amazon has 16-inch M4 Max MacBook Pros (Silver and Black colors) on sale for up to $410 off Apple’s MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather than a third-party... Read more
Red Pocket Mobile is offering a $150 rebate o...
Red Pocket Mobile has new Apple iPhone 17’s on sale for $150 off MSRP when you switch and open up a new line of service. Red Pocket Mobile is a nationwide MVNO using all the major wireless carrier... Read more
Switch to Verizon, and get any iPhone 16 for...
With yesterday’s introduction of the new iPhone 17 models, Verizon responded by running “on us” promos across much of the iPhone 16 lineup: iPhone 16 and 16 Plus show as $0/mo for 36 months with bill... Read more
Here is a summary of the new features in Appl...
Apple’s September 2025 event introduced major updates across its most popular product lines, focusing on health, performance, and design breakthroughs. The AirPods Pro 3 now feature best-in-class... Read more
Apple’s Smartphone Lineup Could Use A Touch o...
COMMENTARY – Whatever happened to the old adage, “less is more”? Apple’s smartphone lineup. — which is due for its annual refresh either this month or next (possibly at an Apple Event on September 9... Read more
Take $50 off every 11th-generation A16 WiFi i...
Amazon has Apple’s 11th-generation A16 WiFi iPads in stock on sale for $50 off MSRP right now. Shipping is free: – 11″ 11th-generation 128GB WiFi iPads: $299 $50 off MSRP – 11″ 11th-generation 256GB... Read more
Sunday Sale: 14-inch M4 MacBook Pros for up t...
Don’t pay full price! Amazon has Apple’s 14-inch M4 MacBook Pros (Silver and Black colors) on sale for up to $220 off MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather... Read more
Mac mini with M4 Pro CPU back on sale for $12...
B&H Photo has Apple’s Mac mini with the M4 Pro CPU back on sale for $1259, $140 off MSRP. B&H offers free 1-2 day shipping to most US addresses: – Mac mini M4 Pro CPU (24GB/512GB): $1259, $... Read more

Jobs Board

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.