SQL Server Interview Topic 21: Query Test Round Practice
This topic helps you prepare for live SQL query-writing rounds. Interviewers may give a table structure and ask you to write queries.
You should be able to read a requirement, choose the right SQL feature, and write the query step by step.
Q140. How do you approach a SQL query test?
Quick interview answer:
First understand the required output. Then identify tables, join columns, filters, grouping, sorting, and expected row count. Write a simple query first, test it mentally, then improve it.
Study in detail: Real-World SMS Scenarios - This article gives practice scenarios.
Q141. How would you find students who have no marks?
Quick interview answer:
Use LEFT JOIN from Student to ExamMarks and filter rows where the marks table id is NULL. This shows students without matching marks records.
Study in detail: LEFT and RIGHT JOIN - This lesson explains missing related data.
Q142. How would you find duplicate mobile numbers?
Quick interview answer:
Use GROUP BY MobileNumber and HAVING COUNT(*) > 1. This shows mobile numbers used by more than one student.
Study in detail: GROUP BY and HAVING - This article explains duplicate checks.
Q143. How would you find the top student in each class?
Quick interview answer:
Use a window function such as ROW_NUMBER partitioned by class and ordered by marks descending. Then select rows where row number is 1.
Study in detail: Window Functions - This lesson explains ranking per group.
Q144. How would you safely update one student's mobile number?
Quick interview answer:
Use UPDATE with a WHERE condition on the primary key, such as StudentId. Before updating, run a SELECT with the same WHERE condition to verify the row.
Study in detail: Update and Delete - This article explains safe updates.
In query tests, speak your thought process. Interviewers value clear problem solving, not only the final SQL.