To sum and group by in SQL in Oracle, you can use the "GROUP BY" clause along with the "SUM" function. This allows you to perform calculations on a specific column while grouping the results based on another column or columns.

Here is an example query:

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SELECT column1, SUM(column2) FROM table_name GROUP BY column1; |

In this query, "column1" represents the column you want to group the results by, while "column2" represents the column you want to sum.

The "SUM" function calculates the total sum of the values in "column2" for each unique value in "column1". The result will be a set of grouped rows, where each row represents a unique value in "column1" along with the sum of "column2" for that particular group.

You can also include additional columns (non-aggregate columns) in the "SELECT" clause to get more detailed information about each grouped row.

This technique is useful when you want to perform calculations on specific groups of data, such as finding the total sales for each product or the sum of salaries for each department in a company.

## How to calculate the sum of a column excluding null values in Oracle SQL?

You can calculate the sum of a column excluding null values in Oracle SQL by using the following query:

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SELECT SUM(column_name) FROM table_name WHERE column_name IS NOT NULL; |

Replace `column_name`

with the actual name of the column you want to calculate the sum of, and `table_name`

with the actual name of the table that contains the column.

The `WHERE column_name IS NOT NULL`

condition ensures that only non-null values are included in the sum calculation.

## What is the difference between the SUM and TOTAL functions in Oracle SQL?

In Oracle SQL, both SUM and TOTAL functions are used to calculate the total of a given column or expression. However, there are some key differences between them:

SUM function:

- The SUM function is an aggregate function that computes the sum of all the values in a column or expression.
- It is typically used to find the total sum of numeric values, such as integers or decimals.
- NULL values in the column or expression are ignored by the SUM function.
- The SUM function can be combined with the GROUP BY clause to calculate the sum for each group.

TOTAL function:

- The TOTAL function is a window or analytic function that calculates the running total or cumulative sum of a column or expression.
- It is used to calculate the sum for each row based on the rows that precede it.
- Unlike the SUM function, the TOTAL function includes NULL values in the calculation.
- The TOTAL function requires an ORDER BY clause to define the order in which the rows are processed for the cumulative sum.

In summary, while the SUM function calculates the total sum of a column or expression, the TOTAL function calculates the cumulative sum of a column or expression based on the order of the rows.

## How to calculate the average of a specific column in Oracle SQL?

To calculate the average of a specific column in Oracle SQL, you can use the AVG function. The syntax to calculate the average of a column is as follows:

```
1
``` |
```
SELECT AVG(column_name) FROM table_name;
``` |

Replace `column_name`

with the name of the column for which you want to calculate the average, and `table_name`

with the name of the table from which you want to retrieve the data.

For example, let's say you have a table named "employees" with columns "name" and "salary", and you want to calculate the average salary of all the employees. The query would be:

```
1
``` |
```
SELECT AVG(salary) FROM employees;
``` |

This will return the average salary of all employees.

## How to calculate the sum of values in a specific column for each group using the GROUP BY clause in Oracle SQL?

To calculate the sum of values in a specific column for each group using the GROUP BY clause in Oracle SQL, you can follow these steps:

- Write a SELECT statement to retrieve the required column and the column that you want to calculate the sum on.
- Use the GROUP BY clause to group the data based on the column you want to group by.
- Use the SUM function to calculate the sum of values in the specified column.
- Run the SQL query to get the desired result.

Here's an example illustrating how to calculate the sum of the "sales" column for each "category" in a table called "products":

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SELECT category, SUM(sales) AS total_sales FROM products GROUP BY category; |

In this example, we are calculating the sum of the "sales" column for each unique value in the "category" column. The result will display the "category" and the corresponding sum as "total_sales" for each group.

Note: Replace "products" with your actual table name, "category" with the column you want to group by, and "sales" with the column you want to calculate the sum on.