L&T Company Programming Program

What is the difference between primary key and unique key?
A)Primary Key is used to identify a column (record) in a table, whereas Unique-key is to prevent duplicate values in a row (with the exception of a null entry) B)By default SQL-engine creates Non-Clustered Index on primary-key if not exists and Clustered Index on Unique-key C)Primary key does not include Null values, whereas Unique-key can
D)Table can have multiple primary key but can have single Unique-key E)You can change or delete primary values, but Unique-key values can not be changed

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c)Primary key does not include Null values, whereas Unique-key can
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A is the right Solution
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L&T Other Question

Eight people J, K, L, M, N, O, P and Q are sitting around a circular table, facing the centre, not necessarily in the same order. O is sitting third to the right of M. There is only one person sitting between M and J. There are only three people between J and K. P is an immediate neighbour of J. There are only three people between P and L. N is second to the right of P. What is position of N with respect to K?
A.Second to the left B.Second to the right C. Third to the left D.Third to the right E.Fourth to the left Two same glasses are respectively 2/3rd and 3/4th full of milk. They are then filled with water and the contents is mixed in a tumbler. The ratio of milk and water in the tumbler is?
A. 17:7 B 8:3 C. 21:11 D. 27:10