SQL, Advance Java, Corporate Java, Rays Technologies, SunilOS, Rays Indore, Rays Pune, Rays Delhi

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SQL

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SQL
It stands for Structured Query Language.
Query to add/update/delete/read records from
database.

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Sales System Tables
Order
id date part_id qty
1 2/12/2006 1 100
2 3/15/2006 2 200
3 3/15/2006 3 100
4 4/5/2006 2 300
5 4/15/2006 3 200
6 6/15/2006 1 400
7 8/1/2006 1 100
Part
id name color unit_id
1 Nut Grey 2
2 Bolt Grey 3
3 Screw Silver 2
Unit
id city Capacity
1 New York 1000
2 London 2000
3 Paris 3000
Primary Key
Foreign Key
Foreign Key
Primary
Key

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SQL Statements
 DDL data definition language
o Statement for defining tables
 Create & Alter Tables
o Statement for deleting tables
 Drop table
 DML data manipulation language
o Statement for Queries
 SELECT * FROM part;
o Statement for Inserting and Updating data
 INSERT into part VALUES(4,'plat','Green',1);
 UPDATE part SET color = 'Green', unit_id = 1 where id=4;
o Statement for deleting rows
 DELETE FROM part WHERE id=4;
 DCL – Data Control Language
o Commit : Saves data changes
o Rollback : Reverts data changes
o Savepoint : transaction demarcation.

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DDL Statements
CREATE TABLE `part` (
`id` int(11) NOT NULL,
`name` text,
`color` text,
`unit_id` int(11) default NULL,
PRIMARY KEY (`id`)
)
ALTER TABLE `part`
ADD `color` text/

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DML Statements
 Statement to insert all columns into part table.
INSERT INTO part VALUES (4,'plat','Green',1);
 Statement to insert id and name columns into part table.
INSERT INTO part (id,name) VALUES (4,'plat');
 Statement to update color and unit_id into part table.
UPDATE part SET color = 'Green', unit_id = 1 WHERE id=4;
 Statement to delete record from part table.
DELETE FROM part WHERE id=4;

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DML - Select
 Get all parts
o SELECT * FROM part;
 Get all parts’ ids, names and colors
o SELECT id, name, color FROM part;
 Get all grey color parts
o SELECT * FROM part WHERE color = ‘Grey’
 Get all parts sorted by name
o SELECT * FROM part ORDER BY name
 Get all parts those name starts with “N”
o SELECT * FROM part WHERE name LIKE ‘N%’

8. Pagination
Get parts record number 11 to 20 sorted by name
o SELECT * FROM part LIMIT 10,10 ORDER BY name
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DML – Aggregate Functions
How many parts are there?
o SELECT count(*) from part;
o SELECT count(id) from part;
How many parts have been sold?
o SELECT sum(qty) from order
Which is the biggest deal so far?
o SELECT max(qty) from order;
Which is the minimum deal so far?
o SELECT min(qty) from order;

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Joins
 Get parts with their cities of units.
o Columns :part.id, name, color, unit.city
o Tables :part & unit
o Condition :part.unit_id = unit.id;
 SELECT part.id, name, color, unit.city FROM part, unit
WHERE part.unit_id = unit.id;

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Aliases
 SELECT p.id PartID, name, color, u.city FROM part p,
unit u WHERE p.unit_id = u.id
 Or
 SELECT p.id as PartID, name, color, u.city FROM part as
p, unit as u WHERE p.unit_id = u.id

12. SQL IN/BETWEEN
 Get the list of all Silver and Grey parts.
o SELECT * FROM part WHERE color IN ('Grey','Silver')
 Get orders those ordered quantities are between 100 to 200.
o SELECT * from orders WHERE qty BETWEEN 100 AND 200
 Get part counts for each color.
o SELECT color, count (*) part FROM part GROUP BY color
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Nested Query
A Query can be nested in another query.
Get part ids those are ordered more than 100.
o SELECT part_id FROM orders WHERE qty > 100
Get part names those are ordered more than 100.
o SELECT name FROM part
o WHERE id IN
o ( SELECT part_id FROM orders WHERE qty > 100)

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Joins
Outer Join
Inner Join
Left Join
Right Join

15. Joins
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SELECT * from TableA A
LEFT JOIN TableB B
ON A.Key = B.Key
SELECT * from TableA A
RIGHT JOIN TableB B
ON A.Key = B.Key
SELECT * from TableA A
OUTER JOIN TableB B
ON A.Key = B.Key
SELECT * from TableA A
INNER JOIN TableB B
ON A.Key = B.Key

16. Database elements
 Index
o Pointer to records. Makes searching faster.
o One table may have multiple indexes.
o Index can be created on single or multiple columns.
 Views
o Logical Tables.
 Triggers
o Before or After of INSERT/UPDATE/DELETE.
 Stored Procedure
o Do not return a value. Like a void method.
 Stored Function
o Returns a value.
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17. Disclaimer
This is an educational presentation to enhance the skill
of computer science students.
This presentation is available for free to computer
science students.
Some internet images from different URLs are used in
this presentation to simplify technical examples and
correlate examples with the real world.
We are grateful to owners of these URLs and pictures.
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18. Thank You!
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