Question

If the PIPES_AS_CONCAT is disabled, ‘abc’ || ‘xyz’ results in ____________

(a) 1

(b) 0

(c) error

(d) -1

I have been asked this question by my school teacher while I was bunking the class.

This intriguing question comes from Expression Evaluation and Type Conversion topic in portion Data Types of MySQL

Answer 1

Correct choice is (b) 0

Explanation: When the SQL mode PIPES_AS_CONCAT is disabled, the SQL standard ‘||’ operation for string concatenation is not valid in MySQL. Both operands are converted to zero. So the result is zero.