Recall & Review
beginner
What is a union in Tableau?
A union combines rows from two or more tables with the same columns into one table, stacking data vertically.
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beginner
What is a join in Tableau?
A join combines columns from two tables based on a related key, merging data horizontally.
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beginner
Name the four common types of joins in Tableau.
Inner join, Left join, Right join, and Full outer join.
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beginner
When should you use a union instead of a join?
Use a union when you want to add more rows from similar tables, like combining monthly sales data from different files.
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intermediate
What happens if you join tables on a key that has no matching values?
Depending on join type, unmatched rows may be excluded (inner join) or included with nulls (left, right, full outer joins).
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Which operation stacks data vertically in Tableau?
✗ Incorrect
A union stacks rows from tables with the same columns vertically.
Which join type returns only matching rows from both tables?
✗ Incorrect
Inner join returns only rows with matching keys in both tables.
If you want to combine sales data from January and February files, which should you use?
✗ Incorrect
Union combines rows from similar tables, perfect for monthly sales files.
What does a full outer join do?
✗ Incorrect
Full outer join returns all rows from both tables, with nulls where no match exists.
Which is NOT true about joins in Tableau?
✗ Incorrect
Joins combine columns horizontally; stacking rows vertically is done by unions.
Explain the difference between a union and a join in Tableau.
Think about how data is combined: rows vs columns.
You got /4 concepts.
Describe a real-life example when you would use a union and when you would use a join.
Consider data from different files vs related data in tables.
You got /4 concepts.