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Introduction
Simple CASE WHEN
Searched CASE WHEN
CASE WHEN with aggregates
15. CASE WHEN with SUM continued
CASE WHEN with GROUP BY
Summary

## Instruction

Great! The use of CASE WHEN together with SUM is actually so important that we should do one more exercise here. Are you ready?

## Exercise

Count the number of candidates with preferred_contact set to:

• mobile (mobile_sum).
• e-mail (email_sum).
• mail (mail_sum).
• with NULL (null_sum).

Only count candidates whose score in math and score in language are both greater than or equal to 30.

### Stuck? Here's a hint!

SELECT