Database Fundamentals, and SQL Language Elements

SQL Tutorial 4: Database Fundamentals

i) Database Fundamentals

ii) SQL Language Elements
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i) Database Fundamentals

• Database Server instance contains multiple databases
• Database contains multiple Tables
• Table contains multiple records (rows and columns)

What is a Database?

• A Database is a systematic collection of data.
• Databases support storage and manipulation of data
• Databases make data management easy.

Table and Record

• A Table in a Relational Database is a predefined format of rows and columns that define an entity.
• Each column contains a differnt type of attribute and each ror coresponds to a single record
• Each Table is provided with a name.

Example: Table name: Students

SID        Name   Address    ContactNo
10001      abcd   errtt,ttt    9878787878
10002      xyz   fwew,er    8786767676

What is DBMS?

• A Database management System is software designed to assist in maintaining and utilizing large collection of data.

• The alternative to use a DBMS is to store the data in files and write application specific code to manage it.

Using a DBMS to manage data has many advantages:

• Data Independence
• Efficient Data Access
• Data Integrity and security
• Data Administration
• Concurrent Access and Data Recovery
etc...

Types of Database Management System

1) Hierarchical DBMS
2) Network DBMS
3) Relational Database Management System (RDBMS)
Ex: Oracle, MS SQL Server, MySQL, DB2 etc...
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ii) SQL Language Elements

1) Identifiers: 
Names of Database Objects such as Tables, Views, Columns etc...

2) Data Types:
Define the type of data that is contained by a Column

3) Constants:
Symbols that represent specific data types

4) Operators:
Perform Arithmetic, Comparison, and Logical Operations

5) Functions: Built-in Functions to perform specific operations

6) Clauses: 
Constituent components of statements and queries.

7) Expressions:
Produce scalar values, or tables containing of columns and rows of data.

8) Queries: 
Retrieve the data based on specific criteria, this an important element of SQL.

9) Statements Etc...
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Create - It is a Command

Create Database gcreddyabc - It is a Statement

Oracle

Create Database gcreddyabc - It create a Database called gcreddyabc in Oracle RDBMS

MS SQL Server

Create Database gcreddyabc - It create a Database called gcreddyabc in MS SQL Server RDBMS
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Use / Practice SQL 

SQL is used to communicate with databases, it is the Standard Language for
Relational Database management Systems.

Database Engine is required to use/practice SQL Commands/Queries, we can use any
Database Engine either Oracle, MySQL or MS SQL Server etc...

MS SQL Server:
MS SQL Server is a Commercial Software but Microsoft providing Free Edition also.

Microsoft SQL Server Express Edition

Download and Install MS SQL Server Express Edition
(Windows 7 - MS SQL Server 2014 Express Edition, 
Windows 10 - 2014 or 2016 Express Edition)

After In Editor, 
Write SQL statements and Execute.
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