## SQL Server SUM() Function and Syntax

Whether you are a seasoned SQL Server professional or a beginner, you must be familiar with the SUM() function. As the name suggests, the SUM() function is used to calculate the sum of values.

It is an aggregate function that is widely used in many databases, including SQL Server.

## Syntax of the SUM() function

The basic syntax of the SUM() function is quite simple:

`SELECT SUM(column_name) FROM table_name;`

Here, the `column_name`

is the name of the column for which you want to calculate the sum, and `table_name`

is the name of the table that contains that column. While this basic syntax works fine in most cases, you may need to use additional options to customize the SUM() function.

### ALL option in SUM() function

The ALL option is used to include all the rows in the calculation, regardless of their values. In other words, if you use the ALL option, the SUM() function will consider all the rows, including the duplicates and the null values.

The syntax of the SUM() function with the ALL option is as follows:

`SELECT SUM(ALL column_name) FROM table_name;`

Let’s take an example to understand this better. Suppose you have a table that contains the following data:

ID | Value |
---|---|

1 | 100 |

2 | 50 |

3 | NULL |

1 | 150 |

If you want to calculate the sum of the Value column, including all the values (including the duplicates and null values), you can use the following query:

`SELECT SUM(ALL Value) FROM Table1;`

The output of this query will be 300, as it considers all the values in the Value column, including the duplicates and null values.

### DISTINCT option in SUM() function

The DISTINCT option is used to include only the unique values in the calculation. In other words, if you use the DISTINCT option, the SUM() function will consider only the distinct values in the column.

The syntax of the SUM() function with the DISTINCT option is as follows:

`SELECT SUM(DISTINCT column_name) FROM table_name;`

Let’s take the same example as before, but suppose you want to calculate the sum of the Value column, including only the unique values (excluding the duplicates and null values). You can use the following query:

`SELECT SUM(DISTINCT Value) FROM Table1;`

The output of this query will be 150, as it considers only the distinct values in the Value column, which are 100 and 50.

### Difference between ALL and DISTINCT options

The main difference between the ALL and DISTINCT options is in how they treat duplicate and null values. The ALL option considers all the values in the column, including the duplicates and null values, while the DISTINCT option considers only the distinct values in the column, excluding the duplicates and null values.

### When to use ALL and DISTINCT options

The decision to use the ALL or DISTINCT option in the SUM() function depends on your data and what you are trying to accomplish. If you are interested in the total value of all the values in the column, including duplicates and null values, then you should use the ALL option.

On the other hand, if you are interested in the total value of only the unique values in the column, then you should use the DISTINCT option.

## Conclusion

In summary, the SUM() function in SQL Server is a powerful tool that helps you calculate the sum of values. By using the ALL and DISTINCT options in the SUM() function, you can customize your calculations to include or exclude duplicates and null values, depending on your data and your needs.

Knowing how to use the SUM() function, along with its options, is an essential skill for any SQL Server developer or DBA.

## Examples of SQL Server SUM() Function

The SUM() function in SQL Server is a powerful tool that helps you calculate the sum of values in a table. In this article, we will cover some examples of how to use the SUM() function, including simple and complex examples that use group by, having clause, and expressions.

### Example 1: Simple Sum

Let’s start with a simple example of how to use the SUM() function to calculate the total stock of a product. Suppose we have a table named ProductStock that contains the following data:

ProductID | ProductName | Stock |
---|---|---|

1 | Product A | 10 |

2 | Product B | 20 |

3 | Product C | 30 |

4 | Product D | 40 |

5 | Product E | 50 |

To calculate the total stock of all the products in the table, we can use the following query:

`SELECT SUM(Stock) AS TotalStock FROM ProductStock;`

The command would return a single value, which is the sum of all the values in the Stock column, the total stock of all the products in the table.

### Example 2: Group By

Now let’s see how to use the GROUP BY clause with the SUM() function to calculate the total stock of all the products by store. For this example, we will use a table named ProductSales that contains the following data:

Store | ProductID | Quantity |
---|---|---|

A | 1 | 10 |

A | 2 | 20 |

A | 3 | 30 |

B | 1 | 40 |

B | 2 | 50 |

B | 3 | 60 |

To calculate the total stock of all the products by store, we can use the following query:

`SELECT Store, SUM(Quantity) AS TotalStock FROM ProductSales GROUP BY Store;`

The command would return two rows, one for each store, and the total stock of all the products sold in each store.

### Example 3: Having Clause

Now let’s see how to use the HAVING clause with the SUM() function to filter results based on the sum of the values. For this example, we will use the same table as in Example 2, but we want to find only the stores that have sold more than 100 units in total.

To filter the results based on the total sum, we can use the following query:

`SELECT Store, SUM(Quantity) AS TotalStock FROM ProductSales GROUP BY Store HAVING SUM(Quantity) > 100;`

The command would return a single row, which is the store that has sold more than 100 units in total. Example 4: Expression

### Example 4: Expression

Lastly, let’s see how to use expression with the SUM() function to calculate the total net value of sales orders.

For this example, we will use a table named OrderDetails that contains the following data:

OrderID | ProductID | Quantity | Price |
---|---|---|---|

1 | 1 | 4 | 10.00 |

2 | 2 | 3 | 5.00 |

3 | 1 | 2 | 10.00 |

4 | 3 | 1 | 20.00 |

5 | 1 | 3 | 10.00 |

To calculate the net value of all the sales orders, we need to multiply the quantity by the price and then sum up all the values. We can achieve this by using an expression with the SUM() function, as shown below:

`SELECT SUM(Quantity * Price) AS NetValue FROM OrderDetails;`

The command would return a single value, which is the net value of all the sales orders in the table.

## Conclusion

In conclusion, The SUM() function is a useful tool in SQL Server that helps you calculate the sum of values in a table. In the examples above, we explored how to use the SUM() function in various scenarios, including simple and complex examples.

By mastering the SUM() function and its various options, you can easily analyze your data and obtain valuable insights. In this article, we explored examples of how to use the SUM() function in SQL Server to calculate the total value of data.

We learned how to use the function to calculate the total stock of the product, the total stock of all products by store, and how to filter results based on total values using the GROUP BY and HAVING clauses. We also looked at how to use an expression to calculate the net value of sales orders.

The examples illustrated the importance of the SUM() function in analyzing data and its flexibility to adapt to various scenarios. By mastering the function and its options, you can easily analyze your data and obtain valuable insights.