Chapter 3.pptx Oracle SQL or local Android database setup SQL, SQL-Lite, coding the database class, building and executing queries

Database in Android
Android Data Managenent using
SQL Lite

What is SQL lite..?
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SQLite is a relational database management system
contained in a C programming library. In contrast to many
other database management systems, SQLite is not a
client–server database engine. Rather, it is embedded into
the end program.
SQLite is ACID-compliant and implements most of the SQL
standard, using a dynamically and weakly typed SQL
syntax

Origins of sql lite
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D. Richard Hipp designed SQLite in the spring of 2000
while working for General Dynamics on contract with the
United States Navy. Hipp was designing software used
aboard guided missile destroyers, which were originally
based on HP-UX with an IBM Informix database back-end.
SQLite began as a Tcl extension.
The design goals of SQLite were to allow the program to
be operated without installing a database management
system or requiring a database administrator.

Why sql lite
●
●
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No server is required
Object(document) based design
Reqire Zero(less) Configration
One machine database
Multitasking database

Using SQL databases in Android
Android (as well as iPhone OS) uses an embedded standalone
program called sqlite3 which can be used to
create a database,
indices,
views,
Insert rows,
change rows,
define SQL tables,
queries,
triggers
delete rows,
run queries and
administer a SQLite database file.

How to create a SQLitedatabase
Open the database according to the flags OPEN_READWRITE OPEN_READONLY
CREATE_IF_NECESSARY . Sets the locale of the database to the thesystem's current
locale.
public static SQLiteDatabase.openDatabase(
Stringpath, SQLiteDatabase.CursorFactory factory, int flags )
Parameters
path to database file to open and/or create
factory an optional factory class that is called to instantiate a cursor when
query is called, or null for default
flags to control database access mode
Returns the newly opened database
Throws SQLiteException if the database cannot be opened

How to create a SQLitedatabase
SQLiteDatabase db=this.openOrCreateDatabase
( "myfriendsDB",MODE_PRIVATE, null);
where the assumed prefix for the database stored in the devices ram is:
"/data/data/<CURRENT_namespace>/databases/". For instance if this app is
created in a namespace called “cis493.sql1”, the full name of the newly created
database will be: “/data/data/cis493.sql1/databases/myfriendsDB”.
MODEcould be: MODE_PRIVATE, MODE_WORLD_READABLE, and
MODE_WORLD_WRITEABLE. Meaningful for apps consisting of multiples
activities

no Method & Description
1 openDatabase(String path, SQLiteDatabase.CursorFactory factory, int
flags, DatabaseErrorHandler errorHandler)
This method only opens the existing database with the appropriate
flag mode. The common flags mode could be OPEN_READWRITE
OPEN_READONLY
2 openDatabase(String path, SQLiteDatabase.CursorFactory factory, int
flags)
It is similar to the above method as it also opens the existing database but it
does not define any handler to handle the errors of databases

no Method & Description
3 openOrCreateDatabase(String path,
SQLiteDatabase.CursorFactory factory)
It not only opens but create the database if it not exists. This method
is equivalent to openDatabase method
4 openOrCreateDatabase(File
file,SQLiteDatabase.CursorFactory factory)
It is similar to the above method as it also opens the existing database but it
does not define any handler to handle the errors of databases

Executing SQL commands on the
Database
Action queries and Retrieval queries represent the most common operations
against the database
Retrieval query : typically a SQL-Select command in which a table holding a
number of fields and rows is produced as an answer to a data request.
Action query : usually performs maintenance and administrative tasks such as
manipulating tables, users, environment, etc.

Transection Processing
The transaction is defined between the methods: beginTransaction and
endTransaction. You need to issue the setTransactionSuccessful() call
to commit any changes. the absence of it provokes an implicit rollback;
consequently the database is reset to the state previous to the beginning
of the transaction

Creating a Table
We will use the execSQL(…)method to manipulate SQL action queries.
db.execSQL("create table tblAMIGO(" + " recIDinteger PRIMARY KEY autoincrement,
" + " name text,
"+ " phone text );
" );

Create table
The database data types are very simple, for instance we will use: text,varchar,
integer, float, numeric, date, time, timestamp, blob, boolean, and so on.
1.In general, any well-formed SQL action command (insert, delete, update,
create, drop, alter, etc.) could be framed inside an execSQL(…) method.
2.You should make the call to execSQLinside of a try-catch-finally block. Be
aware of potential SQLiteExceptionsituations thrown by the method.

Retrieval queries
Retrieval queries are SQL-select statements.
Android offers two mechanisms for phrasing SQL-select statements:
1.Raw queries take for input a syntactically correct SQL-select statement. The
select query could be as complex as needed and involve any number of tables
(remember that outer joins are not supported).
2.Simple queries are compact parametized select statements that operate on a
single table (for developers who prefer not to use SQL).

RawQuery
Cursor c1 = db.rawQuery(
"select count(*) as Total from Student",
null);
The rawQuery contains a select-statement that counts the rows in the table
Student.
2.The result of this count is held in a table having only one row and one column.
The column is called “Total”.
3.The cursor c1will be used to traverse the rows (one!) of the resulting table.
4.Fetching a row using cursor c1 requires advancing to the next record in the
answer set.
5.Later the (singleton) field total must be bound to a local Java variable

Cursors
Android cursor s are used to gain (random) access to tables produced by SQL
select statements.
Cursors primarily provide one row-at-the-time operations on a table. Cursors
include several types of operator
1.Positional awareness operators (isFirst(), isLast(), isBeforeFirst(),
isAfterLast()),
2.Record Navigation (moveToFirst(), moveToLast(), moveToNext(),
moveToPrevious(), move(n))
3. Field extraction (getInt, getString, getFloat, getBlob, getDate, etc.)
4.Schema inspection (getColumnName, getColumnNames, getColumnIndex,
getColumnCount, getCount)

Chapter 3.pptx Oracle SQL or local Android database setup SQL, SQL-Lite, coding the database class, building and executing queries

Cursors provide READ_ONLYaccess to records.
2.Early versions of the Android SDK included cursor commands to
sequentially modify records. Those operators have been deprecated in
Release 1.0.
3.Methods such as cursor.updateInt(...)and cursor.deleteRow(...)are not valid
anymore.
4.Instead use an action SQL command in an execSQL(...)method .

ParametizedRawQuery
String mySQL= "select count(*) as Total "
+ " from Student"
+ " where recID> ?"
+ " and name = ?";
String [] args= {"114337", "Dipak"};
Cursor c1 = db.rawQuery (mySQL, args);

Simple Querie
Simple queries can only retrieve data from a single table.(non-joining ) it is an
template
The method’s signature has a fixed sequence of seven arguments representing:
1.the table name,
2.the columns to be retrieved,
3.the search condition (where-clause),
4.arguments for the where-clause,
5.the group-by clause,
6.having-clause, and
7.the order-by clause.

SQL Action Queries
insert into student values ( ‘Macarena’, ‘555-1234’);
update student set name = ‘Maria Macarena’ where phone = ‘555-1234’;
delete from where phone = ‘555-1234’;
create table Temp ( column1 int, column2 text, column3 date );
drop table Temp;

Insert Operator
public long insert (String table, String nullColumnHack, ContentValues values)

Insertion
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execSQL(String sql, Object[ ] bindArgs)
This method not only insert data , but also used to update
or modify already existing data in database using bind
arguments

update Operator
public int update ( String table,
ContentValues values,
String whereClause, String[ ] whereArgs)
Parameters
table :
values :
the table to update in
a map <name,value> from column names to new column values.
null is a valid value that will be translated to NULL.
whereClause : the optional WHERE clause to apply when updating.
Passing null will update all rows.
Returns : the number of rows affected

delete Operator
public int delete( String table, String whereClause , String[ ] whereArgs)
Parameters
table the table to delete from
whereClause the optional WHERE clause to apply when deleting. Passing
null will delete all rows.
Returns the number of rows affected if a whereClauseis passed in,
0 otherwise.
To remove all rows and get a count pass "1" as the whereClause

Chapter 3.pptx Oracle SQL or local Android database setup SQL, SQL-Lite, coding the database class, building and executing queries

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