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What is the database?
The database is a computer file that be used to store the data
instructured way, this database file can be managed by software to
make itaccessible to application and to manage the data
What are kinds of database?
a flat database : the database without any relations between its
tablesand this kind is useless in the big project with bid
dataRelational database : that eliminating the repeating in data
and Retrievethis data more efficient
Why we using software like SQL not store the data in text
file?
Because of these reasons1-data integrity2- over data3-outdated
data4-retriving, filtering, searching5-protect data from
unauthorized
What is a SQL?
Structure Query Language (SQL) is an application that allows you
tocreate and manage database
RDBMS
RDBMS stands for Relational Database Management System.RDBMS is
the basis for SQL, and for all modern database systems like MSSQL
Server, IBM DB2, Oracle, MySQL, and Microsoft Access.this system
makes managing data easy by taking care of many of themost
difficult tasks , and save effort and duplicate the data more
thanoncethe data integrity is the main job of the RDBMSThe data in
RDBMS is stored in database objects called tables.A table is a
collections of related data entries and it consists of columnsand
rows.
What Can SQL do?
SQL can execute queries against a databaseSQL can retrieve data
from a databaseSQL can insert records in a databaseSQL can update
records in a databaseSQL can delete records from a databaseSQL can
create new databasesSQL can create new tables in a databaseSQL can
create stored procedures in a databaseSQL can create views in a
databaseSQL can set permissions on tables, procedures, and
views
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Types of Transact-SQL Statements
1-Data Definition Language statements (DDL)2-Data Manipulation
Language statements (DML)3- Data Control Language statements
(DCL)
DDL
Define the data objectCREATE object nameTo create a new object
like new database , new table,..ALTER object nameTo make any update
in an existing objectDROP object nameTo delete any existing object
like database, table, .
DML
TO deal with the data inside these objectSELECTTo retrieve
existing data and can filter this data in retrievingINSERTTo insert
new data in tableUPDATETo update information in existing
dataDELETETo delete any data
DCL
SET or change permissions1-GRANT
Allow user to work with data2-DENY
Prevent the user from inheriting the permission through its
group3-REVOKE
Remove granted or denied permission
