State the output of the following query: \[ \text{SELECT LENGTH(MID('INFORMATICS PRACTICES',5,-5));} \]

Question

Given table 'StudAtt' with structure as (Rno, Attdate, Attendance). Identify the suitable command to add a primary key to the table after creation.
Note: We want to make both Rno and Attdate columns as primary key.

Answer 1

Step 1: Function understanding.
- MID(string, start, length) extracts a substring from \textit{string}, beginning at \textit{start}, with a length of \textit{length}.
- LENGTH(string) returns the character count of the string.
Step 2: Query Issue.
In this query: \texttt{MID('INFORMATICS PRACTICES', 5, -5)}. The length argument in SQL cannot be negative. Therefore, this query is invalid.
Step 3: Outcome.
Instead of generating a substring, the database will produce an error.
Final Answer: \[\boxed{\text{ERROR}}\]

ENO	SALARY
A101	4000
B109	NULL
C508	6000
A305	2000

List-I (Aggregate function)	List-II (Description)
(A) `count(marks)`	(III) Count all non null values of marks column
(B) `count()`	(I) Count all rows
(C) `avg(marks)`	(II) Finding average of non null values of marks
(D) `sum(marks)`	(IV) Finding sum of all marks

State the output of the following query: \[ \text{SELECT LENGTH(MID('INFORMATICS PRACTICES',5,-5));} \]

Show Hint

The Correct Option is D

Solution and Explanation

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