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# ORDER BY Clause in SQL

The `ORDER BY` clause in SQL is used to sort the result set of a query in ascending or descending order based on one or more columns. It is often used to organize data in a meaningful way, such as sorting names alphabetically or numbers numerically.

## Key Points

1. **Sorting Data**: The `ORDER BY` clause sorts the result set in ascending (`ASC`) or descending (`DESC`) order.
2. **Multiple Columns**: You can sort by multiple columns, with the primary sort column listed first.
3. **Default Order**: If no order is specified, the default is ascending (`ASC`).
4. The `ORDER BY` clause is used with the `SELECT` statement.

## Syntax

```sql theme={"system"}
SELECT column1, column2, ...
FROM table_name
ORDER BY column1 [ASC|DESC], column2 [ASC|DESC], ...;
```

* `column1, column2, ...`: The columns you want to retrieve.
* `table_name`: The table from which to retrieve data.
* `ASC`: Sorts the result set in ascending order (default).
* `DESC`: Sorts the result set in descending order.

## Examples

Suppose you have a table named `Employees` that stores employee details.

Table: Employees

| EmployeeID | Name    | City       | State      | Salary |
| ---------- | ------- | ---------- | ---------- | ------ |
| 1          | Anand   | Chennai    | Tamil Nadu | 50000  |
| 2          | Bala    | Coimbatore | Tamil Nadu | 60000  |
| 3          | Kavitha | Karaikal   | Puducherry | 55000  |
| 4          | Raj     | Madurai    | Tamil Nadu | 70000  |
| 5          | Kumar   | Trichy     | Tamil Nadu | 45000  |

To retrieve employees sorted by their names in ascending order:

```sql theme={"system"}
SELECT Name, City, Salary
FROM Employees
ORDER BY Name ASC;
```

| Name    | City       | Salary |
| ------- | ---------- | ------ |
| Anand   | Chennai    | 50000  |
| Bala    | Coimbatore | 60000  |
| Kavitha | Karaikal   | 55000  |
| Kumar   | Trichy     | 45000  |
| Raj     | Madurai    | 70000  |

### Sorting in Descending Order

To sort the employees by their salary in descending order:

```sql theme={"system"}
SELECT Name, City, Salary
FROM Employees
ORDER BY Salary DESC;
```

| Name    | City       | Salary |
| ------- | ---------- | ------ |
| Raj     | Madurai    | 70000  |
| Bala    | Coimbatore | 60000  |
| Kavitha | Karaikal   | 55000  |
| Anand   | Chennai    | 50000  |
| Kumar   | Trichy     | 45000  |

### Sorting by Multiple Columns

You can sort by multiple columns. For example, sort employees first by their state in ascending order and then by their salary in descending order.

```sql theme={"system"}
SELECT Name, City, State, Salary
FROM Employees
ORDER BY State ASC, Salary DESC;
```

| Name    | City       | State      | Salary |
| ------- | ---------- | ---------- | ------ |
| Kavitha | Karaikal   | Puducherry | 55000  |
| Raj     | Madurai    | Tamil Nadu | 70000  |
| Bala    | Coimbatore | Tamil Nadu | 60000  |
| Anand   | Chennai    | Tamil Nadu | 50000  |
| Kumar   | Trichy     | Tamil Nadu | 45000  |

### Using ORDER BY with WHERE Clause

You can combine the `ORDER BY` clause with the `WHERE` clause to filter and sort data. For example, retrieve employees from Tamil Nadu and sort them by salary in descending order.

```sql theme={"system"}
SELECT Name, City, Salary
FROM Employees
WHERE State = 'Tamil Nadu'
ORDER BY Salary DESC;
```

| Name  | City       | Salary |
| ----- | ---------- | ------ |
| Raj   | Madurai    | 70000  |
| Bala  | Coimbatore | 60000  |
| Anand | Chennai    | 50000  |
| Kumar | Trichy     | 45000  |

## Practical Use Case

Suppose you have a table named `Students` that stores student details, and you want to retrieve students sorted by their percentage in descending order.

**Table: Students**

| StudentID | Name    | City       | State      | Percentage |
| --------- | ------- | ---------- | ---------- | ---------- |
| 1         | Ram     | Chennai    | Tamil Nadu | 92         |
| 2         | Karthik | Coimbatore | Tamil Nadu | 88         |
| 3         | David   | Bangalore  | Karnataka  | 95         |
| 4         | Kannan  | Karaikal   | Puducherry | 91         |
| 5         | Siva    | Madurai    | Tamil Nadu | 89         |

```sql theme={"system"}
SELECT Name, City, Percentage
FROM Students
ORDER BY Percentage DESC;
```

| Name    | City       | Percentage |
| ------- | ---------- | ---------- |
| David   | Bangalore  | 95         |
| Ram     | Chennai    | 92         |
| Kannan  | Karaikal   | 91         |
| Siva    | Madurai    | 89         |
| Karthik | Coimbatore | 88         |

## Key Takeaways

1. The `ORDER BY` clause is used to sort the result set in ascending (`ASC`) or descending (`DESC`) order.
2. You can sort by one or more columns, with the primary sort column listed first.
3. The default sorting order is ascending (`ASC`).
4. The `ORDER BY` clause can be combined with the `WHERE` clause to filter and sort data.
5. Sorting data makes it easier to analyze and interpret query results.