TCS Technical Interview Questions [ Part 4]
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16) What is the difference between the foreign key and the reference key?
Reference Key is the primary key that is referenced in the other table (linked via the other tables Foreign Key). Foreign Key is how you connect the second table to the primary tables Primary Key (or Reference Key).
17) What is the difference and similarity between C and C++?
- C++ has classes whereas C did not have classes.
- C does not support function overloading. In C, for input or output, we use functions like gets(), puts(), scanf(), printf(), etc
- C does not support exception handling.
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18) The structural difference between bitmap and b-tree index?
- Btree
It is made of branch nodes and leaf nodes. Branch nodes hold prefix key value along with the link to the leaf node and the leaf nodes contain the indexed value and rowed. - Bitmap
It consists merely of bits for every single distinct value. It uses a string of bits to locate rows in a table quickly. It is used to index low cardinality columns.
19) What is the difference between a Clustered index and a non-clustered index?
- Clustered Index
o Only one per table
o Faster to read than non clustered as data is physically stored in index order - Non-Clustered Index
o Can be used a lot of times per table
o Quicker for insert and update operations than a clustered index
20) Differentiate between socket and session?
- The socket is the combination of IP address and Port Number (in pairs)
- The session is a Logical Connectivity between the source and destination.
