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58 lines
1.4 KiB
58 lines
1.4 KiB
# SUM |
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The `SUM()` function in SQL is used to calculate the sum of a column. This function allows you to add up a column of numbers in an SQL table. |
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The syntax for SUM is as follows: |
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```sql |
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SELECT SUM(column_name) FROM table_name; |
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``` |
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Where `column_name` is the name of the column you want to calculate the sum of, and `table_name` is the name of the table where the column is. |
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For example, consider the following `ORDER` table: |
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``` |
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| OrderID | Company | Quantity | |
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|------------|---------|----------| |
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| 1 | A | 30 | |
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| 2 | B | 15 | |
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| 3 | A | 20 | |
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``` |
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If you want to find the total quantity, you can use `SUM()`: |
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```sql |
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SELECT SUM(Quantity) AS TotalQuantity FROM Order; |
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``` |
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Output will be: |
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``` |
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| TotalQuantity | |
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|---------------| |
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| 65 | |
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``` |
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**Note:** The `SUM()` function skips NULL values. |
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One of the common use cases of `SUM()` function is in conjunction with `GROUP BY` to get the sum for each group of rows. |
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Example: |
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```sql |
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SELECT Company, SUM(Quantity) AS TotalQuantity |
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FROM Order |
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GROUP BY Company; |
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``` |
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This will give us the sum of `Quantity` for each `Company` in the `Order` table. |
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``` |
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| Company | TotalQuantity | |
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|-----------|----------------| |
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| A | 50 | |
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| B | 15 | |
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``` |
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Notably, in all databases, including MySQL, PostgreSQL, and SQLite, the `SUM()` function operates the same way.
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