design
method of database initially,and build new database and simple application with database
system.
SQL is a kind of coumputer language for database only,it can not only query database
but
selection also can be done on the database, add or delete, update, and jump
and other various operations.
SQL include DDL,DML,DCL,with the same language style and all of activities of
life cycle of database can be done.
Users dont have to know about access path,the selection of it and the operation of
SQL
are
automatic
done
by
system.It
reduces
users
’
pressure
and
improve
the
independence of data
It
adopt
operation
mode
of
collection
,it
is
a
self-contained
and
embedded
language,and supply two different operarion way with a same grammer structure,it makes
users feel flexible and convenient.
SQL is a language which is similar to oral English , it
is easy to be studied and
used.