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Explain the difference between using functions along with and without grouping attributes in relational algebra. Give examples.
Ans: Group functions are used to group data of similar type. GAMMA = grouping and aggregation Applying GAMMAL(R)• Group R according to all the grouping attributes on list L.1. That is: form one group for each distinct list of values for those attributes in R.• Within each group, compute AGG(A ) for each aggregation on list L.• Result has one tuple for each group:1. The grouping attributes and2. Their group's aggregations. Example: Grouping /Aggregation R = ( A B C ) 1 2 3 4 5 6 1 2 5 GAMMAA,B,AVG(C) (R) = ? First, group R by A and B : A B C 1 2 3 1 2 5 4 5 6 Then, average C within groups: A B AVG(C) 1 2 4 4 5 6
A relation instance indicates as r is a collection of tuples for a given relational schema at a exact point of time. A relation state r of the relation schema R (A 1 ,A 2 ,.....
a project based on normalization with first, second and third normalization. There need to be a diagram also
The users who use easy-to-use menu are called ? The users who use easy to use menu are called as Naïve users.
Consider the table student and list names of students in the departments other than maths and computer. SELECT std_name FRM student WHERE dept_name NOT IN (‘Maths','Computer);
Develop C# schoolproject ASAP Helping me with schoolproject. The project is prepared in C# and haves a database connection. We have some small issues asking up data from t
Storage Of Database On Hard Disks At this point, it is worthwhile to note the difference among the terms file Organisation and the access method. A file organisation shows to t
Define the basic operations of the relational algebra? Ans: Basic operators of relational algebra are: 1. Union (∪) - Selects tuples which are in either P or Q or in bot
(a) Differentiate between information and data . (b) List and briefly explain five potential benefits of the database approach compared to conventional file systems. (c) Diff
definition and its work
Describe sequential file organization. Explain the rules for (i) Inserting a new record. (ii) Deleting an existing record. Ans:A sequential f
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