Simple Databases

Setting Up SQLite in Eclipse

• Use SQLite – already installed on the linux machines

• Download one of the following two SQLite JDBC drivers– sqlitejdbc-v056.jar– sqlite-jdbc-3.7.2.jar

• Store it wherever you like

At Least Two Methods to Get it Working

• Both basically put the jar you just downloaded in the build path for your project.

• Technique 1:Right click on your project icon in the Package Explorer. In the menu select Build Path and then Add External Archives. Use the folder explorer that appears to find the jar file you downloaded and select “open” and it will be made part of your program’s build path.

At Least Two Methods to Get it Working

• Technique 2: – Select Run at the top of the page.– Select Run Configurations… about 5 lines down.– Select the Classpath tab in the row of tabs underneath the

name of your main routine.– In the Classpath window select User Entries– Select Add External Jars… from the right column– Now navigate to the folder where you stored your sqlite jdbc jar

file– Select the jar file– Hit the Open button– Then select Apply button

Installing SQLite3 on Linux

• Linux – Download the source file from (usually the second

file listed) http://www.sqlite.org/download.html– tar –xzvf the downloaded file– cd to the new folder– ./configure– make– make install

Installing SQLite3 on a Mac

• On a recent OS you don’t have to, it is already there

Installing SQLite3 on Windows

• Download the first two zip files from the section labeled Precompiled Binaries for Windows.

• Unzip them and place the three resulting files in C:\WINDOWS\system32 (or any directory on you PATH.– Alternative: I created a new directory called SQLite

in C:\Program Files (x86) and placed the three files in that location. I then extended the PATH variable to search that location

Adding the SQLite Manager to FireFox

• You can manage an SQLite database using the command line and text-based SQLite commands, but, it is easier to the SQLite Manager extension you can get for Firefox.

• First, start Firefox• Then go to

https://addons.mozilla.org/en-US/firefox/addon/sqlite-manager/

and hit the green “Add to Firefox” button and install the extension.

• After it is installed you can click on the “SQLite Manager” under the Tools tab at the very top.

Using SQLite ManagerCreating/Deleting/Closing/Connecting To a Database

• Creating a Database– Database Tab >> New Database

• Enter name (.sqlite will be appended to end)– Navigate to desired folder and click “Select Folder”

• Close a Database– Database >> Close Database

• Connect to Database– Database >> Connect Database

• Navigate to desired folder, select sqlite file, hit Open

• Delete Database– From command line , Windows Explorer, or Finder navigate to

appropriate folder and remove file containing database

Using SQLite ManagerCreating a Table

• Adding a simple Table– Table >> Create Table

• Fill in Table Name text box with the new table name• For each column (attribute)

– Fill in Column Name text box with column name unique to this table– Select Data Type

» Only real types are Text, Numeric, Integer, Real, None (Blob)– Select/Enter Constraint: Primary Key, Autoinc, Allow Null, Unique, Default Value

– Enter attributes or columns• Give it a name• Give it a data type• Identify it as having

– Enter a Column Name (e.g. Id)– Select a Data Type (e.g. Integer)– Select the appropriate check boxes

» Primary Key» Autoinc» Allow Null (Not NULL)» Unique» Default: Enter Value (rarely use one of possible selections)

– Hit OK Button

Using SQLite ManagerViewing Database

• Select a Table• Select Structure tab– Shows the corresponding Create statement

• Operations (also in the Structure tab)– Drop– Empty– Rename

Using SQLite ManagerAdding Data

• Select Table on Left >> Select Browse and Search tab– Add a tuple• Hit Add Button, Fill in values (default shown), hit OK

button• Notice SQL statement

– Update a tuple (Edit)• Select Row, Hit Edit Button, Modify Values, hit OK

– Delete a tuple• Select Row, Hit Delete Button (you better be sure)

Using SQLite ManagerSearching Database

• Select a Table• Select Browse & Search tab– Hit Search button– Enter operations and values for all attributes in

query– Hit OK Button

SQL Statements by Example

• Will be used in JDBC• Execute SQL button• All previous operations and much more can be

done with SQL Statements• SQL Manger used primarily for viewing

Create Table• CREATE TABLE Person (

PersonId Integer Primary Key AutoIncrement ,/* It must always be non-null.

Autoincrement only allowed on Integer Primary Key*/

PersonName Text, -- Notice it can be nullBirthdate Text NOT NULL)

• CREATE TABLE Marriage (MarriageId Integer Primary Key,Husband Integer REFERENCES Person(PersonId), -- one way to specify foreign keysWife Integer,FOREIGN KEY (Wife) REFERENCES Person(PersonId)) – another way to specify foreign keys

• There is a Default Primary Key if none specified– As if there were the attribute: ROWID Primary Key

• Turning on and off foreign key checking– PRAGMA foreign_keys = ON;– PRAGMA foreign_keys = OFF;

DROP, EMPTY, or RENAME Table

• DROP TABLE Person;• DELETE FROM Person;• ALTER TABLE Person RENAME TO Student; -- not used much

Adding Tuples To A Table• INSERT INTO Person VALUES(1, “William”, “Male”, “222 West Elm”, 27);

-- The order of values is important

• INSERT INTO Person (Id, Name, Gender, Address, Age)VALUES (2, “William”, “Male”, “222 West Elm”, 27);

• INSERT INTO Person (Age, Address, Gender, Name, Id)VALUES (27, “222 West Elm”, “Male”, “William”, 3);

• INSERT INTO Person (Id, Name)VALUES (4, “Bill”); -- other values become NULL

Modifying a Tuple

• UPDATE Person SET Name = “Bill”, Phone = “801-555-5555”WHERE Name = “William”;

Simple Search

• SELECT * FROM GradeBookWHERE Grade = “A”;

• SELECT * FROM GradeBookWHERE Grade = “A” AND Section = 1;

• SELECT * FROM GradeBookWHERE MidTerm1 IS NULL;

Deleting a Tuple

• DELETE FROM Class List WHERE Section = 2;

236 Review or Project, or Select, or Rename

• or Project – Select Execute SQL Tab– Sample SQL statements

• SELECT x,z FROM Person;• SELECT * FROM Person;

– Semi colon not needed in SQL Manger but is needed in JDBC• or Select

– Select Execute SQL Tab– Sample SQL statements

• SELECT * FROM T WHERE x = y;

• or Rename – renames column in resulting table– Used primarily to control Join– Select Execute SQL Tab

• SELECT X AS A, Y, Z FROM T;– Multi-word names should be quoted

Queries“Union”

• SELECT Name, AddressFROM ClassList

UNION SELECT Name, Address

FROM FacultyList;• Doesn’t have to be Union compatible– The names from the second table are “renamed”

to the names of the first table

Queries“Difference”

• SELECT Name, Address FROM Staff

EXCEPT SELECT Name, Addr

FROM Students

Queries“Intersection”

• SELECT Name, Address FROM Staff

INTERSECT SELECT Name, Addr

FROM Students

QueriesCartesian Product

• SELECT * FROM Person CROSS JOIN Spouse;

QueriesNatural Join

• SELECT * FROM Person NATURAL JOIN Spouse;• To rename before natural joins use nested queries or

sub queries– CREATE TABLE Person (Id Integer Primary Key, Name TEXT);– CREATE TABLE Spouse(Id Integer Primary Key, Spouse Integer);– SELECT Spouse1, Name AS Spouse2

FROM Person NATURAL JOIN(SELECT Spouse AS Id, Name AS Spouse1

FROM Person NATURAL JOIN Spouse);

– Any place you can put a Table name in a query you can put: (SELECT …)

QueriesInner Join

• SELECT Customers.AcctNumber, Customers. CustnameFROM

Customers INNER JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

• SELECT Customers.AcctNumber, Customers. CustnameFROM

Customers JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

• Join controlled by “ON” clause

QueriesLeft Outer Join

• SELECT Customers.AcctNumber, Customers. CustnameFROM

Customers LEFT OUTER JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

• SELECT Customers.AcctNumber, Customers. CustnameFROM

Customers LEFT JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

• All tuples in Left table of the join that do not match tuples from the right table according to the “ON” clause are preserved by appending a so-called generated “Default” tuple from the right table.

QueriesRight Out Joins

• There is NO Right Outer Join in SQLite– If you wanted

Customers.AcctNumber, Customers. CustnameFROM

Customers RIGHT OUTER JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

– You would useCustomers.AcctNumber, Customers. Custname

FROM cust_invoice LEFT OUTER JOIN Customers ON Customers.AcctNumber = cust_invoice.AcctNumber;

QueriesOuter Joins

• There is NO Outer Join in SQLite– If you wanted

Select Customers.AcctNumber, Customers. CustnameFROM

Customers OUTER JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

– You would useSelect Customers.AcctNumber, Customers. Custname

FROM cust_invoice LEFT OUTER JOIN Customers ON Customers.AcctNumber = cust_invoice.AcctNumber

UNIONCustomers.AcctNumber, Customers. Custname

FROM Customers LEFT OUTER JOIN cust_invoiceON Customers.AcctNumber = cust_invoice.AcctNumber;

Views --Giving a Query a Name

• CREATE VIEW TableName AS SELECT …• CREATE VIEW ParentsChildren AS SELECT PersonName AS ParentName, ChildName FROM Person JOIN (SELECT ParentId, PersonName AS ChildName FROM Person JOIN Children WHERE Person.PersonId = Children.ChildId )

WHERE Person.PersonId = ParentId;

• You cannot edit (delete, insert, or update) a view• Also an example of nested queries

Using The Command Line ForCreating/Deleting/Closing/Connecting To a Database

• Creating a Database– sqlite3 newDBName.sqlite

• If the file newDBName.sqlite does not exist it will create a new database with that name for you

• Close a Database– While in sqlite3 type .quit at the prompt

• Connect to Database– Assuming there is an existing “DB.sqlite” database

Sqlite3 DB.sqlite

• Delete Database from the command line– In Windows type: del DB.sqlite– In Unix or a Mac type : rm DB.sqlite

Transactions

• Treat sequence of 2 or more SQL statements as if it were a single statement.

• Constraints not checked until the end of the transaction

• ACID: Atomic Consistent, Isolated, and Durable

TransactionsAutocommit or Atomic Transactions

• Autocommit or atomic transactionUPDATE authors

SET au_fname = 'John‘WHERE au_id = '172-32-1176'

TransactionsMulti-Statement Transactions

• BEGIN TRANSACTIONUPDATE authors

SET au_fname = 'John' WHERE au_id = '172-32-1176‘;

UPDATE authorsSET au_fname = 'Marg‘WHERE au_id = '213-46-8915'

COMMIT TRANSACTION;• The word “COMMIT” may be replace by “END”• SavePoints• Rollbacks• IF statements

IF (…) BEGINROLLBACK TRANSACTION [TO SAVEPOINT savepointName]END ELSE BEGINCOMMIT TRANSACTIONEND

Using JDBC• Sample.java• Sample2.java – Shows drop table and insert• Empty Table and Rename Table• Update (Modify)• Simple Select• Deleting a Tuple• Select, Project, Rename• Union, Intersection, Difference• Joins• Transactions• Views• Support Classes:

SetUp.java SetUp4.java

SetUp2.java Table.java

SetUp3.java QueryResult.java