SQL and BI Developer Interview Questions and Answers

Tableau blend is combining data from different data sources, while join is combining data from the same data source.

• Tableau blend is used to combine data from different data sources in a single view.

• Join is used to combine data from the same data source based on a common key.

• Blending is done at the visualization level, while joining is done at the data source level.

• Blending allows for combining data that may not have a direct relationship, while joining requires a common key ...read more

Use GROUP BY clause to count sum of sales by customer in MySQL.

• Use GROUP BY customer_id to group sales by customer

• Use SUM(sales_amount) to calculate total sales for each customer

Use SQL query to count the maximum sales by customer.

• Use GROUP BY clause to group the sales by customer.

• Use MAX() function to find the maximum sales for each customer.

• Use COUNT() function to count the maximum sales for each customer.

Filters in SQL are used to restrict the result set based on specified criteria.

• Filters are used in the WHERE clause of a SQL query to specify conditions that must be met for a row to be included in the result set.

• Filters can be used to restrict the result set based on one or more columns, using comparison operators such as =, <>, >, <, >=, <=, etc.

• Filters can also be combined using logical operators such as AND, OR, and NOT to create complex conditions.

• Examples: WHERE age > 1...read more

Different types of joining in SQL include inner join, outer join, left join, right join, and full join.

• Inner join: Returns rows when there is a match in both tables

• Outer join: Returns all rows when there is a match in one of the tables

• Left join: Returns all rows from the left table and the matched rows from the right table

• Right join: Returns all rows from the right table and the matched rows from the left table

• Full join: Returns rows when there is a match in one of the tables