Simple Databases

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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 Manager
Creating/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 Manager
Creating 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 Manager
Viewing Database
• Select a Table
• Select Structure tab
– Shows the corresponding Create statement
• Operations (also in the Structure tab)
– Drop
– Empty
– Rename
Using SQLite Manager
Adding 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 Manager
Searching 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 null
Birthdate Text NOT NULL)
CREATE TABLE Marriage (
MarriageId Integer Primary Key,
Husband Integer REFERENCES Person(PersonId), -- one way to specify foreign keys
Wife 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 GradeBook
WHERE Grade = “A”;
• SELECT * FROM GradeBook
WHERE Grade = “A” AND Section = 1;
• SELECT * FROM GradeBook
WHERE 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, Address
FROM 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
Queries
Cartesian Product
• SELECT * FROM Person CROSS JOIN Spouse;
Queries
Natural 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 …)
Queries
Inner Join
• SELECT
Customers.AcctNumber, Customers. Custname
FROM
Customers INNER JOIN cust_invoice
ON Customers.AcctNumber = cust_invoice.AcctNumber;
• SELECT
Customers.AcctNumber, Customers. Custname
FROM
Customers JOIN cust_invoice
ON Customers.AcctNumber = cust_invoice.AcctNumber;
• Join controlled by “ON” clause
Queries
Left Outer Join
•
•
SELECT
Customers.AcctNumber, Customers. Custname
FROM
Customers LEFT OUTER JOIN cust_invoice
ON Customers.AcctNumber = cust_invoice.AcctNumber;
SELECT
Customers.AcctNumber, Customers. Custname
FROM
Customers LEFT JOIN cust_invoice
ON 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 socalled generated “Default” tuple from the right table.
Queries
Right Out Joins
• There is NO Right Outer Join in SQLite
– If you wanted
Customers.AcctNumber, Customers. Custname
FROM
Customers RIGHT OUTER JOIN cust_invoice
ON Customers.AcctNumber = cust_invoice.AcctNumber;
– You would use
Customers.AcctNumber, Customers. Custname
FROM
cust_invoice LEFT OUTER JOIN Customers
ON Customers.AcctNumber = cust_invoice.AcctNumber;
Queries
Outer Joins
• There is NO Outer Join in SQLite
– If you wanted
Select Customers.AcctNumber, Customers. Custname
FROM
Customers OUTER JOIN cust_invoice
ON Customers.AcctNumber = cust_invoice.AcctNumber;
– You would use
Select Customers.AcctNumber, Customers. Custname
FROM
cust_invoice LEFT OUTER JOIN Customers
ON Customers.AcctNumber = cust_invoice.AcctNumber
UNION
Customers.AcctNumber, Customers. Custname
FROM
Customers LEFT OUTER JOIN cust_invoice
ON 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 For
Creating/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
Transactions
Autocommit or Atomic Transactions
• Autocommit or atomic transaction
UPDATE authors
SET au_fname = 'John‘
WHERE au_id = '172-32-1176'
Transactions
Multi-Statement Transactions
•
•
•
•
•
BEGIN TRANSACTION
UPDATE authors
SET au_fname = 'John'
WHERE au_id = '172-32-1176‘;
UPDATE authors
SET au_fname = 'Marg‘
WHERE au_id = '213-46-8915'
COMMIT TRANSACTION;
The word “COMMIT” may be replace by “END”
SavePoints
Rollbacks
IF statements
IF (…) BEGIN
ROLLBACK TRANSACTION [TO SAVEPOINT savepointName]
END ELSE BEGIN
COMMIT TRANSACTION
END
Using JDBC
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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

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