Zenoti Data Migration Consultant Interview Questions and Answers

SQL query order of execution determines the sequence in which different parts of a query are processed.

• SQL query is parsed and checked for syntax errors

• Query optimizer creates an execution plan

• Data is retrieved from tables based on the execution plan

• Filters and joins are applied to the retrieved data

• Aggregations and calculations are performed on the filtered data

Null data values in joins can be handled using COALESCE function or LEFT JOIN with IS NULL condition.

• Use COALESCE function to replace null values with a specified default value

• Use LEFT JOIN with IS NULL condition to include rows with null values in the result set

• Consider using CASE statements to handle null values based on specific conditions