Recent questions tagged databases

How aggrigate functions in query will behave in data contains NULL values.I think answer should be D as all aggrigatre functions EXCEPT count will ignore NULL values. so,...

Maximum number of nodes in B+ tree possible with order 4 and height 6 is ___________.Is the answer should be 1365 or 5461.

Given the following functional dependencies$\left\{X \rightarrow W, X \rightarrow Y, Y \rightarrow Z, Z \rightarrow PQ\right\}$Consider the $FD$ set implied using above $...

THE DIFFERENCE BETWEEN FOLLOWING 2 EXPRESSIONS?a. (selection)year≥2009(takes) NATURAL JOIN  studentb. (selection)year≥2009(takes NATURAL JOIN student)

Consider the following Two Transactions.A) How many recoverable schedules can be formed over $T_{1}$ & $T_{2}$ ?$51$$52$$55$$56$ B) How many cascadeless recoverable s...

Suppose we have a relation $R(X, Y, Z, W)$ with the FD's:$$X \to Y, Y \to Z, Z \to W$$Which one of the following decompositions is not lossless (i.e., for some instance o...

Consider a relation R(A B C) with attribute size of A as 8 bytes. Disk block size is 512 bytes and block pointer is 8 bytes. The best choice for degree (maximum value) fo...

Given R(ABCD) andAB → C ;ABD → C ;ABC → D ;AC → Dwhich the highest possible normal form for the above relation ?

Given a relation R (ABCD), and the following FDs- A->BCDBC->ADD->B.which is the highest normal form the table is in.a) 1NFb) 2NFc)3NFd) BCNF

________ index is denseA) Primary indexB) clustered indexC) secondary index on candidate keyD) all

Use the following tables for the below queries wherever table $1$ and table $2$ are used:Select *From Table 1Where not exists (Select $T_{2}B$ From Table 2 where $T_{2}B ...

I am confused about this problem:Relation A - m tuplesRelation B - n tuplesWhat is the maximum and minimum size of natural join?According to this, maximum can be - min(m...

Given answer: DPlease explain

ABC52110NULL21523In the above relation T the output of query:select * from T group by B;ABC10NULL2521Can anyone explain why this is the output?

Given answer is 2, but I think that for each multivalue attribute we need a relation and one for the main entity, therefore 3 should be the answer. Please correct me if I...