Sql Interview Fundamentals Recruiters Expect (2025

Everyone says “I know SQL”… until the interview starts.

This is where most Data Analyst candidates get exposed — not because SQL is hard, but because they learned how to write queries, not why databases work the way they do.

𝐏𝐚𝐲 𝐀𝐟𝐭𝐞𝐫 𝐏𝐥𝐚𝐜𝐞𝐦𝐞𝐧𝐭 𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐏𝐫𝐨𝐠𝐫𝐚𝐦- 𝐆𝐞𝐭 𝐏𝐥𝐚𝐜𝐞𝐝 𝐈𝐧 𝐓𝐨𝐩 𝐌𝐍𝐂'𝐬

Recruiters quietly expect clarity on fundamentals that go beyond SELECT statements. These concepts show whether you can actually work with real business data.

Why SQL Interviews Feel Harder Than Practice

In interviews, you’re tested on:

How you think about data
How tables relate to each other
How databases behave at scale
Whether your logic holds in real-world scenarios

Not memorized syntax. Understanding.

Core SQL Concepts You’re Expected to Know

1. Joins (Not Just Syntax)

INNER vs LEFT vs RIGHT vs FULL joins
When joins change row counts
How joins affect NULL values
Real use cases (customers without orders, missing data)

2. Keys & Relationships

Primary key vs Foreign key
Composite keys
Why keys matter for joins and data integrity
What breaks when keys are missing

3. Normalization & Denormalization

Why databases are normalized
1NF, 2NF, 3NF (conceptual understanding)
When denormalization is actually preferred

4. Triggers & Stored Logic

What triggers are
When they’re used
Why analysts should understand them (even if they don’t write them)

5. OLTP vs OLAP

Transactional vs analytical databases
Why queries behave differently
Why reporting systems are designed separately

6. Analytics & BI Logic (Tableau / Reporting)

How aggregations really work
Row-level vs aggregate-level logic
Why dashboards sometimes show “wrong” numbers

7. Real-World Data Scenarios

Duplicate records
Missing values
Slowly changing data
Performance considerations

The Interview Reality

Most candidates:

Can write queries
Freeze when asked why
Struggle with follow-up questions

Strong candidates:

Explain trade-offs
Talk through assumptions
Connect SQL logic to business impact

That’s the difference.

Use This as a Revision Checklist

Don’t rush this. Save it. Revise slowly. Explain concepts out loud.

This single habit can upgrade how interviewers see you.

📎 Reference Document: https://docs.google.com/document/d/1pl8kSlQ81j1xSOv1GNmgt1yo1fbOpEPm/edit?usp=drivesdk&ouid=111775972531446461704&rtpof=true&sd=true

If you’re aiming for Data Analyst roles in 2025–2026, understanding SQL at this level is not optional anymore.

It’s expected.

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