Which join type in Tableau will keep all rows from the left table and only matching rows from the right table?
Think about which join keeps everything from the first table regardless of matches.
A Left Join keeps all rows from the left table and matches rows from the right table where possible. If no match exists, the right side columns are null.
Given two tables in Tableau: Customers with 5 rows and Orders with 8 rows. If you perform an inner join on CustomerID, and 3 customers have orders, how many rows will the joined table have?
Inner join keeps only matching rows. Each order belongs to one customer.
Since 3 customers have orders, and there are 8 orders total, the inner join will have 8 rows (one per order matching a customer).
You joined two tables in Tableau using an inner join on ProductID. However, some rows in the result have nulls in the right table's columns. What is the most likely cause?
Check if the keys you join on have the same data type in both tables.
If the join keys have different data types (e.g., string vs number), Tableau cannot match them properly, causing nulls in joined columns even with an inner join.
You want to create a dashboard showing total sales by customer after joining Customers and Sales tables. Which visualization best shows this?
Think about showing total sales per customer clearly.
A bar chart with Customer Name on the X-axis and Total Sales on the Y-axis clearly shows sales per customer after joining the tables.
You have two tables: Employees and Projects. Some employees are not assigned to any projects yet, and some projects have no employees assigned. You want a view that shows all employees and all projects, matching where possible, and showing nulls where no match exists. Which join type should you use in Tableau?
Think about including all rows from both tables, even if no match exists.
A Full Outer Join includes all rows from both tables, matching where possible and filling with nulls where no match exists, which fits this scenario.