Merging queries (joins) in Excel - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a 'join' when merging queries in Excel?

A join combines rows from two tables based on a related column, like matching names or IDs, to create a single table with combined information.

beginner

Name the four common types of joins used in merging queries.

The four common join types are:<br>1. Inner Join - keeps only matching rows.<br>2. Left Join - keeps all rows from the left table and matching rows from the right.<br>3. Right Join - keeps all rows from the right table and matching rows from the left.<br>4. Full Outer Join - keeps all rows from both tables, matching where possible.

beginner

How do you perform a merge (join) in Excel using Power Query?

In Power Query:<br>1. Load both tables.<br>2. Click 'Merge Queries'.<br>3. Select the matching columns in each table.<br>4. Choose the join type (e.g., Inner, Left).<br>5. Click OK to create the merged table.

beginner

What happens if you use an Inner Join but some rows don't have matches?

Rows without matches in either table are excluded from the result. Only rows with matching keys in both tables appear.

beginner

Why might you use a Left Join instead of an Inner Join?

Use a Left Join when you want to keep all rows from the first (left) table, even if there is no matching data in the second (right) table. This helps keep all your main data and add extra info where available.

Which join type keeps all rows from both tables, matching where possible?

A Full Outer Join

B Left Join

C Right Join

D Inner Join

A Full Outer Join keeps all rows from both tables, matching rows where possible and filling gaps with blanks.

In Excel Power Query, what is the first step to merge two tables?

A Click 'Merge Queries' after loading tables

B Sort the tables alphabetically

C Create a Pivot Table

D Use VLOOKUP formula

You first load both tables into Power Query, then click 'Merge Queries' to start joining them.

What does an Inner Join do with rows that don't have matching keys?

A Moves them to the bottom

B Includes them with blanks

C Duplicates them

D Excludes them

Inner Join excludes rows without matching keys in both tables.

Which join type keeps all rows from the left table and adds matching rows from the right?

A Right Join

B Left Join

C Inner Join

D Full Outer Join

Left Join keeps all rows from the left table and adds matching rows from the right table.

When merging queries, what is the key column used for?

A To sort the data alphabetically

B To format the output

C To match rows between tables

D To calculate totals

The key column is used to find matching rows between the two tables.

Explain how you would merge two tables in Excel using Power Query and describe the difference between Inner Join and Left Join.

Think about which rows stay or go when you pick each join type.

Describe a real-life situation where merging queries with a join would be useful and which join type you would choose.

Imagine you have two lists and want to combine them based on a common ID.