How to Calculate the Total Count of Grouped Data in SQL?

Calculating SUM of Grouped Counts in SQL

In a table where data is grouped by a specific field, such as name, it can be useful to calculate the total count across all groups. This can be achieved using the SUM function and window functions.

To implement this, consider the following SQL query:

SELECT name, COUNT(name) AS count, SUM(COUNT(name)) OVER() AS total_count
FROM Table
GROUP BY name;

• SELECT: This clause specifies which columns to retrieve in the resulting table. In this case, it selects the 'name' column, the 'COUNT(name)' column, and a column named 'total_count'.
• COUNT(name): This function counts the number of occurrences of the 'name' column for each distinct name. It returns a column with the count for each row.
• SUM(COUNT(name)) OVER(): This expression uses the SUM function with a window function to calculate the sum of the 'COUNT(name)' values across all groups. The OVER() clause specifies the window of rows to sum over. In this case, it is the entire table, so it calculates the sum of counts for all rows.
• FROM Table: This clause specifies the table from which to retrieve the data.
• GROUP BY name: This clause groups the rows in the table by the 'name' column. This ensures that the count is performed for each distinct name.

The output of this query will include a new column named 'total_count', which contains the sum of the counts for all groups. This provides a quick and easy way to calculate the total count of records in the table.

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