Questions tagged sql · medium
Write an SQL query to find the second-highest salary from an employee table.
Explain the differences between Data Warehouse, Data Lake, and Delta Lake
Can you explain the difference between OLTP and OLAP?
Describe a time when you had to optimize a slow SQL query. What steps did you take?
How do you handle NULL values in SQL? Mention functions like COALESCE and NULLIF.
What is the difference between WHERE and HAVING clauses in SQL?
Explain the concept of Broadcast Join in Spark. When should it be used?
What is the difference between SQL and NoSQL databases?
Explain SQL Window Functions with examples.
Explain the use of the MERGE statement in SQL.
How do you handle NULL values in SQL? Mention functions like COALESCE and ISNULL.
How would you handle duplicate records in an SQL table?
SQL query to find the second highest salary from each department.
Write an SQL query to find duplicate emails in a users table.
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