SQL made by IBM in the system R project.

includes relational algebra and tuple calculus

The data definition language includes:

• create table (define columns)
• alter table (add columns)
• create index (indexes relation based on attributes)
• create view (make virtual relation)

no deletion because you can always just do a projection

The data manipulation language is:

• insert into values -adds a tuple
• delete(relation) where(conditions on attributes) -removes tuples
• update set(new values) where(selects tuples) -modify tuples
• select from(relations) where(selection criteria) -subset (performs selection and join)

Also some aggregate operations (used with select)

• count
• min
• max
• avg
• sum

Set operations

• in
• exists (element contained)
• not exists
• contains (subset check)
• not contains
• union
• intersect
• minus

example:

who makes more than Jacque?

Select e1.Name, e1.PayRate

From EMPLOYEE e1, EMPLOYEE e2

where e1.PayRate e2.PayRate AND e2.Name=''Jacques''

Another example:

want itemized bills from employee #3

Relations:

• Bill - bill #, Employee #, date, total$
• Reciepts - bill#, item#, qty
• inventory - item#, item description, item cost

select receipt.item#, inventory.item_desc,qty,item_cost, qty*item_cost,bill.bill#

from bill, receipt, inventory

where employee#=3 and date=2/21/97

source psfile jl@crush.caltech.edu index relational_language QUEL QBE