What is query optimization in SQL
· SQL & Databases
Improve SQL query performance using execution plans, indexing strategies, and query rewriting techniques.
Category: SQL & Databases
50 questions in SQL & Databases.
How to use self joins
· SQL & Databases
Query hierarchical and relational data within a single table using self joins in SQL.
What are views in SQL
· SQL & Databases
Simplify complex queries and encapsulate logic using SQL views that present virtual tables.
How to use CASE expressions in SQL
· SQL & Databases
Add conditional logic to SQL queries using CASE expressions for computed columns and conditional aggregation.
What is the difference between UNION and UNION ALL
· SQL & Databases
Compare UNION and UNION ALL to decide when to remove duplicates and when to combine result sets quickly.
How to use transactions in SQL
· SQL & Databases
Ensure data integrity by grouping multiple SQL operations into atomic transactions with commit and rollback.
What are database indexes and how to create them
· SQL & Databases
Speed up query performance by understanding and creating indexes on database tables.
How to use Common Table Expressions CTEs
· SQL & Databases
Simplify complex queries and improve readability with named temporary result sets using CTEs.
What are window functions in SQL
· SQL & Databases
Perform advanced analytics across related rows without collapsing groups using SQL window functions.
How to write subqueries in SQL
· SQL & Databases
Nest queries inside SELECT, FROM, and WHERE clauses to perform multi-step data retrieval with subqueries.