SQL Support Engineer Interview Questions and Answers

DROP removes a table, TRUNCATE clears data without logging, and DELETE removes specific rows with logging.

• DROP: Completely removes a table and its structure. Example: DROP TABLE employees;

• TRUNCATE: Deletes all rows in a table but keeps the structure. Example: TRUNCATE TABLE employees;

• DELETE: Removes specific rows based on a condition. Example: DELETE FROM employees WHERE id = 1;

• TRUNCATE is faster than DELETE as it doesn't log individual row deletions.

• DROP cannot be rolled bac...read more

SQL is a programming language used to manage and manipulate relational databases.

• Joins are used to combine data from two or more tables based on a related column

• Aggregate functions perform calculations on a set of values and return a single value

• Create table is used to create a new table in a database

• Update is used to modify existing data in a table

• Truncate is used to delete all data from a table

• Delete is used to remove specific rows from a table

SQL supports several types of joins to combine records from two or more tables based on related columns.

• INNER JOIN: Returns records with matching values in both tables. Example: SELECT * FROM A INNER JOIN B ON A.id = B.id;

• LEFT JOIN (or LEFT OUTER JOIN): Returns all records from the left table and matched records from the right table. Example: SELECT * FROM A LEFT JOIN B ON A.id = B.id;

• RIGHT JOIN (or RIGHT OUTER JOIN): Returns all records from the right table and matched recor...read more

I worked on a data migration project, optimizing SQL queries for a healthcare application to enhance performance and reliability.

• Led a team of 4 in migrating a legacy database to a new SQL Server environment.

• Optimized complex SQL queries, reducing execution time by 30%.

• Implemented data validation checks to ensure data integrity during migration.

• Collaborated with developers to troubleshoot and resolve SQL-related issues.

• Conducted training sessions for team members on best SQL ...read more