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controls ,DDLs, and add-ins with Visual Basic 6 or buy them off shelf from a large number of
third –party software vendors.
Backend Description
SQL is a standard language for communicating with the RDBMS from any tool SQL
can be used by a range of users. It is non-procedural language which looks like English language.
When you enter an SQL statement , it is stored in SQL buffer and remains there until you enter a
new statement.
DDL:-DDL is the part of ESQL. it stands for Data Definition language. It provides
statement for creation and deletion of the database. The DDL statements insulate you from the
low level details of how data is physically stored in the database statement are: CREATE
TABLE,ALTER TABLE ,DROP TABLE etc.
DML:- DML is also the part of SQL .it stands for Data Manipulation Language . it
provides statements For manipulating the database. The DML statements can modify the data
stored in the database, but may cannot change its structure. It includes commands to insert
,delete and modify tuples in the database
Features of SQL
‣ Recovery and concurrency: Concurrency is concerned with the manner in which
multiple users operate the database. Each user can either reflect the updates of a
transaction or can cancel all the updates of a transaction.
‣ Security: The security can be maintained by view mechanism .A view is used to hide
sensitive information and defines only part of a table which should be visible.
‣ Integrity constraints: They are enforced by the system .For example, one can specify
that an attribute of a relation will not take on null values.
What SQL can do?
SQL can retrieve data from a database
SQL can insert records in a database
SQL can update records in a database