Description
When working with SQL queries, can you discuss a situation where you had to choose between using UNION and UNION ALL? What was your decision-making process, and how did it impact the performance of your query?
1. Technical knowledge : Understanding of SQL query commands and their performance implications.
2. Analytical thinking : Ability to analyze the requirements and data to make informed decisions on query optimization.
3. Decision making : Capability to choose the most effective approach to querying data based on specific needs.
4. Problem-solving : Finding the most efficient solutions for data retrieval and manipulation.
1. Assess technical expertise : Gauge the depth of your SQL knowledge and understanding of query optimization.
2. Understand thought process : Learn how you approach and solve technical problems, particularly regarding database management.
3. Evaluate performance consideration : Determine if you consider performance impacts when making technical decisions.
4. Check practical experience : Verify if you have hands-on experience with database querying and optimization.
1. Explain the difference : Clarify the difference between UNION and UNION ALL commands in your answer.
2. Mention real scenarios : Discuss any real-life scenarios where you had to choose one over the other.
3. Talk about performance : Detail how the choice between UNION and UNION ALL can affect the performance of a query.