android sqlite

Let us work with Sqlite
Table of contents
SNO Name Of Content
1 History Of SQLite Database
2 Why SQLite Only???
3 Features Of SQLite
4 Disadvantages Of SQLite
5 Architecture Of SQLite
6 Examples To Do

History
• SQlite is an open source embedded database. The original
implementation was designed by D. Richard Hipp.
• Hipp was designing software used on board guided
missile systems and thus had limited resources to work
with.
• The resulting design goals of SQLite were to allow the
program to be operated without a database installation
or administration.

Why Sqlite Only????
• In android we will use Sqlite database only . Because it is
in built DB in Android SDK more over it is lite weighted
relation DB suitable for Mobile Devices.
• We need not to load any drivers and we need not to
install the Sqlite separately.
• The queries also simple to understand and easy to
implement.

Feature of SQLite
• Application file format – Transactions guarantee ACID
[Atomicity, Consistency , Isolation, Durability] even after
system crashes and power failures.
• Temporary data analysis – Command line client, import
CSV files and use sql to analyze & generate reports .
• Embedded devices – Applicable to small, reliable and
portable like mobiles.
• Portable - uses only ANSI-standard C and VFS, file format
is cross platform (little vs. big endian, 32 vs. 64 bit)

Feature of SQLite
• Reliable – has 100% test coverage, open source code and
bug database, transactions are ACID even if power fails.
• Small – 300 kb library, runs in 16kb stack and 100kb heap.
• Single Database File – An SQLite database is a single
ordinary disk file that can be located anywhere in the
directory hierarchy.
• Readable source code – The source code to SQLite is
designed to be readable and accessible to the average
programmer.

Disadvantages
• High concurrency – reader/writer locks on the entire file.
• Huge datasets – DB file can’t exceed file system limit or
2TB.
• Access control – we don’t have any user interface to
operate Sqlite database objects as in MYSQL / SQL Server
/Oracle. All the objects are virtual. However there are
fewq third party UI are available in the market.
[http://www.sqlabs.net/sqlitemanager.php]

Architecture of Sqlite
The SQL Command Processor will read the SQL Commands from
Interface and it will forward that SQL Query Strings to the
Tokenizer of SQL Compiler
This Virtual Machine will read the code what ever the code generated by the code
generator of the SQL Compiler
This interface will read the SQL queries what ever it is
generated by the user and it will pass this SQL Commands to
the SQL Command Processor

When a string containing SQL statements is to be executed, the
interface passes that string to the tokenizer. The job of the
tokenizer is to break the original string up into tokens and pass
those tokens one by one to the parser. The tokenizer is hand-
coded in C in the file tokenize.c.
The parser is the piece that assigns meaning to tokens based on
their context, it does not leak memory when syntax errors are
encountered, parser assembles tokens into complete SQL
statements
the code generator to produce virtual machine code that will do the work that the SQL
statements request. Ex: vacuum.c and where.c in which where.c handles code generation
for WHERE clauses on SELECT, UPDATE and DELETE statements

The B-tree module requests information from the disk in fixed-
size chunks. The default chunk size is 1024 bytes but can vary
between 512 and 65536 bytes. The page cache is responsible for
reading, writing, and caching these chunks. The page cache also
provides the rollback and atomic commit abstraction and takes
care of locking of the database file.
In order to provide portability between POSIX (Portable Operating System Interface (for
Unix))and Win32 operating systems, SQLite uses an abstraction layer to interface with the
operating system. The interface to the OS abstraction layer is defined in os.h.
An SQLite database is maintained on disk using a B-tree
implementation found in the btree.c source file. A separate B-tree
is used for each table and index in the database. All B-trees are
stored in the same disk file. Details of the file format are recorded
in a large comment at the beginning of btree.c.

Memory allocation and ceaseless string comparison routines are
located in util.c
If you count regression test scripts, more than half the total code
base of SQLite is devoted to testing. There are many assert()
statements in the main code files

Examples To Do
Let us do some coding
Steps in working with Sqlite database:
 Creating Sqlite Object
 Creating Database
 Creating Table
 Working with Tables

Examples To Do
Step:1 Importing package
“android.database.sqlite.SQLiteDatabase”.
Step:2 Creating object
SQLiteDatabase object name=null;

Examples To Do
mydb=openOrCreateDatabase("DatabaseName5",
MODE_PRIVATE,null);
EX:
//mydb is sqlite object name .
//DatabaseName5 is nothing but database name
//MODE_PRIVATE is permissions of a table accessing

Examples To Do
mydb.execSQL("CREATE TABLE IF NOT EXISTS “
+TableName+" (ColumnName DataType);");

Examples To Do
Create:
mydb.execSQL("CREATE TABLE IF NOT EXISTS “
+TableName+" (ColumnName DataType);");
Alter:
ALTER TABLE TableName RENAME TO new-table-name
Drop:
DROP TABLE TableName
(View Source)

Examples To Do
Select:
Cursor c=mydb.rawQuery("SELECT * FROM "+TableName+"
where Name='"+city+"'",null);
Insert:
mydb.execSQL("INSERT INTO "+TableName+“ (Name, Area)“ +
"VALUES ('RedFort','40.8 acres‘);");
Delete:
mydb.execSQL(“Delete"+TableName);
(View Source)

SQLite OpenHelper
• SQLite OpenHelper is a class to manage database creation
and version management.
• This class take care of opening the database if it exists,
creating it if it does not, and upgrading it as necessary.
• This is for creating db “onCreate(SQLiteDataBase)”.
• when the database needs to be upgraded
“onUpgrade (SQLiteDataBase db, int oldVersion, int
newVersion)”.
• when the database has been opened
“onOpen (SQLiteDataBase db)”.

Examples To Do
The below are few kind of applications that we can develop using Sqlite in Android.
Ex:1. Find the registration
form in a Android application
given here.
Functional Description:
Once the user enters all the
details given and click on
Submit Button we need to
SAVE the entire data in
Sqllite using queries.

Examples To Do
Ex:2. Find the List View in a
Android application given here.
Functional Description: Once
the user Stores The data ,You
have to read that data and show
In list view. Example if we have
all country names in the
Database then we can show as
here.

Examples To Do
Ex:3. Find the Tab View in a
Android application given here.
Functional Description: Once
the user Stores The data ,You
have to read that data and show
In Tab View.

android sqlite

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android sqlite