How to apply Group on multiple columns in SQL?

Question

Aryan Kumar · Answer

To apply a GROUP BY clause on multiple columns in SQL, you simply list the column names separated by commas after the GROUP BY keyword. Here's an example: In this example, we have a table called table_name with columns column1, column2, and column3. We want to group the data by values in column1 and column2, and get the sum of values in column3 for each group. The GROUP BY clause includes both column1 and column2, separated by a comma. The SUM function is used to add up the values in column3 for each group. When you run this query, you'll get a result set that shows the values of column1 and column2, and the sum of values in column3 for each group of unique combinations of values in column1 and column2

Krishnapriya Rajeev · Answer

To apply GROUP BY on multiple columns in SQL, we have to include the names of those columns we need, to be separated by commas in the GROUP BY clause. Here's an example SQL query that demonstrates how to use GROUP BY on multiple columns:

SELECT column1, column2, COUNT(*)
FROM table_name
GROUP BY column1, column2;

In this example, column1 and column2 are the names of the columns on which we want to group the data, and table_name is the name of the table from which we want to retrieve the data. The COUNT(*) function is used to count the number of rows that match each combination of values in column1 and column2.

By using GROUP BY with multiple columns, we can get more granular information about the data than we could with a single column.

For example:

We have a table named orders as shown below:

Customer	Month	Amount
John	May	20
Alfiya	June	30
John	May	25
John	August	30
Alfiya	June	10

We might want to know the total amount spent by each customer each month. In this case, we would use GROUP BY on both the customer and month columns:

SELECT customer, month, SUM(amount)
FROM orders
GROUP BY customer, month;

This query would return a table showing the total amount spent by placed by each customer in each month as shown below.

customer	month	SUM(amount)
John	May	45
Alfiya	June	40
John	August	30

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How to apply Group on multiple columns in SQL?

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