Sql calculate percentage group by

Calculating percentages is a common task when dealing with data analysis.

Percentage in sql w3schools

In SQL, the process of calculating percentage may differ based on the database management system being used. In this article, we will discuss various ways to calculate percentages in SQL using different database management systems like MySQL, SQL Server, and PostgreSQL.

1.

MySQL:

In MySQL, you can use the following query to calculate the percentage for each item relative to the total.

“`sql

SELECT item_name,

(item_count / (SELECT SUM(item_count) FROM items)) * 100 as percentage

FROM items;

“`

Here, `item_name` refers to the name of the item and `item_count` refers to the count of each item in the items table.

The query calculates the sum of all item counts and divides that by the individual count for each item, then multiplies by 100 to get the percentage.

2. SQL Server:

In SQL Server, you can use window functions like `SUM()` along with a Common Table Expression (CTE) to calculate percentages.

“`sql

WITH TotalCount AS (

SELECT SUM(item_count) as sum_items

FROM item

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