SQL Server Interview Topic 28: Temp Tables, Table Variables, and CTEs

This topic checks whether you can handle intermediate results in longer SQL queries.

🎯 Interview Goal

You should be able to explain CTEs, temp tables, and table variables in simple words and know when each one is useful.

Q175. What is a CTE?

Quick interview answer:

A CTE is a temporary named result used inside one query. It makes complex SQL easier to read. It is useful when a query has multiple logical steps.

Study in detail: CTEs - This article explains CTEs with examples.

Q176. What is a temp table?

Quick interview answer:

A temp table stores temporary data during a session or procedure. It is useful when intermediate data is reused many times or when a complex operation needs multiple steps.

Study in detail: Advanced Patterns - This lesson explains practical SQL patterns.

Q177. What is a table variable?

Quick interview answer:

A table variable stores a small temporary set of rows inside a batch or procedure. It is usually used for smaller data sets. For larger intermediate results, a temp table may be better.

Study in detail: Stored Procedures and Functions - This lesson connects temporary data to procedures.

Q178. CTE vs temp table: which one do you choose?

Quick interview answer:

Use a CTE when you only need a readable temporary result inside one query. Use a temp table when you need to reuse intermediate data, index it, or break a large process into steps.

Study in detail: Advanced Patterns - This article explains design choices.

Q179. Why can intermediate tables help debugging?

Quick interview answer:

Intermediate tables let you inspect each step of a complex query. This helps when report totals are wrong or when a long query is hard to understand.

Study in detail: Troubleshooting - This lesson explains step-by-step debugging.

💡 Interview Tip

Do not say one option is always best. Explain the situation and why you choose it.