# Basics of Sets and Relations #7

# Basics of Sets and Relations #7

Najeeb_ur_Rehman + 1 comment In which language these queries have written..? 1) Student ⊳⊲(Number=ID) Teaching Assistants 2) π(Name, Number)(Student)

codertoaster + 0 comments These aren't queries, these are notations to represent database operations. Queries are written according to these equations.

But lets be real, nobody cares about these. :P

ahujamayank28aug + 0 comments i dont understand the ques-7 please can u elaborate

Sposibo + 0 comments Does it mean that ⊳⊲ means inner join? I put 2 as answer and it is correct.

Beriljeni + 1 comment please comment that query and please explain that

sathappan + 0 comments We Join the tables using two columns Number and ID.The Join would bring the values which are present in both the tables where the values in Number column matches with the value in ID column.In our case,we have two matching values(3412 and 2341) and so the final output would contain 2 rows with all the columns from both these tables.Since they have asked the count the answer is 2.

sankalp341 + 0 comments but the answer is 2

manetsus + 2 comments First thing is what is the meaning of

`Num`

? There is no attribute like this in the second table. However, I assumed that it meant`ID`

attribute. If it is, then the answer should be`2`

as there are two field matched(`3412`

,`2341`

). But the Accepted answer is`1`

. Am I missing something?PRASHANTB1984Asked to answerChallenge Author + 0 comments **Endorsed by manetsus**Edited as appropriate -- thanks for pointing out

vittadavid8 + 0 comments Confusing for me.

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