DBMS Lesson 5 SQL Part 2

Today our Lesson is about DML.අද අපි කතාකරන්නේ DML ගැන.If you haven't gone through previous Lessons click below links.

Lesson 1,Lesson 2,Lesson 3,Lesson 4 part 1,Lesson 4 part 2,Lesson 5 part 1

What is DML?? DML කියන්නේ මොකක්ද??
Data Manipulation Language(DML) that provides set of operations to support basic data manipulation from a database.
DB එකක මූලික දත්ත මෙහෙයවීම් කිරීම සදහා ලබා දී ඇති  ක්‍රියාවලීන්

Operations like/ක්‍රියාවලීන්

• Retrieval of data/දත්ත ගැනීම්
• Insertion of data/දත්ත ඇතුලත් කිරීම්
• Modification of data/දත්ත වෙනස් කිරීම්
• Deletion of data in a database/දත්ත ඉවත් කිරීම්

Lets talk about how retrieve data from a created database.දත්ත ගැනීම් ගැන අප දැන් කතා කරමු.

There are several clauses used to do that.
DB එකක දත්ත ගැනීම සදහා clauses භාවිතා වේ.

• Select < attribute > From < relation > [ Where < condition > ]

Above written statement is called a QUERY and words like select,from,where etc are the CLAUSES.

ඉහත ලියා ඇති වගන්තිය Query වන අතර select,from,where  යන ඒවා Clauses වේ.

Let's learn those clauses through examples....

Example 1:

Q:Display Supplier details

Example 2:
Q:Display Cities of Suppliers

Example 3:

Q:Display details of suppliers whose status more than 20

Example 4:
Q:Display number and names of suppliers who live in Jaffna

Example 5:
Q:Display details of Suppliers who live in Colombo or whose status equal to 20

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A1:Select SNo,Name,Status,City From Supplier    

A2:Select City from Supplier

      or

     Select * From Supplier

Clause like Distinct can be used to remove duplication

A2:Select Distinct City from Supplier

A3:Select * from Supplier Where Status > 20

A4:Select SNo,Name from Supplier Where City='Jaffna'

A5:Select * from Supplier Where City='Colombo' or Status=20

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Answer 1---> 

Answer 2--->

Answer 2 with distinct->

Answer 3--->

Answer 4--->

Answer 5--->

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Note:Answers are given try them and go through the answers provided..

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