Informatics Practices
Consider the following query :
SELECT name FROM class WHERE subject ............... NULL;
Which comparison operator may be used to fill the blank space in above query ?
- =
- LIKE
- IS
- IS NOT
SQL Queries
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Answer
IS, IS NOT
Reason — In SQL, to check for NULL values, we must use the IS NULL or IS NOT NULL comparison operators. The "=" operator cannot be used for NULL because NULL represents an unknown value, and comparisons using = (equal to) will not work as expected. The LIKE operator is used for pattern matching with strings.
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