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example create a sequence named seqss that starts at 105 has a step of 1 and can take maximum value as 2000 create sequence seqss start with
sequencessequences automatically produce unique numbers are sharable are typically used to make a primary key value replace application code speed up
creating views with replace option this option is used to alter the definition of the view without recreating and dropping it or regranting object
creating views with read only option in the view definition this option is used to make sure that no dml operations can be done on the
creating views with check option this option limits those updates of data values that cause records to go off the view the following instance tells
creating a view a query can be embedded within the create view statement a query can have complex select statements containing join groups and sub-
type of views simple views and difficult viewsfeaturesimple viewscomplex viewsnumber of tablesoneone or morecontain functionsnoyescontain groups
benefits it limits data access it makes difficult queries look easy it permits data independence it presents dissimilar views of the similar
viewsa view is like a window by which data from tables can be changed or viewed the table on which a view is based is known as base table the view is
system level permissions with the use of data dictionary you can view them let us take the table name as usersysprivs used in
with the linear commit protocol sites are connected in a chain and the subtransaction at the left-hand end of the chain initiates the protocol
accessing information about permissions to all users-object level permissions with the use of data dictionary you can see the permissions to user let
the following variant of the primary copy asynchronous-update replication protocol has been proposed for totally replicated systemsa a
example revoke all on emp from example revoke all on emp from
example-grant create session to mca12this command gives system level permission on creating a session - not portablegrant select on emp to
a design a query plan for the following distributed query an application at site b wants to compute a join of student idstudid transcript where
create a new usercreate user lt user name gt identified by lt passwordgtexample create user mca12 identified by w123grant it is used to give database
a distributed transaction consists of subtransactions that execute at different sites and access local dbmss at those sites for example a distributed
data control the data control mostly refers to commands that permit system and data privileges to be passed to several users these commands are
consider a relation s over the attributes a and b with the following characteristics5000 tuples with 10 tuples per pagea 2-level b tree
sub query in the update commandexample double the commission for employees who have got at least 2
insert into command values can be inserted for all columns or for the selected columns values can be given by sub query in place of values parameter
having clause this clause is used for producing conditions on grouped informationexample find maximum salary and department number of those
group by clauses bull it is used to group database tuples on the basis of definite common attribute value like as employees of a department where