ORDER BY in SQL
Structured Query Language (SQL) is a powerful tool for managing and manipulating data in relational databases. One of the key aspects of SQL is sorting and organizing query results, and the ORDER BY clause plays a crucial role in this process.
The ORDER BY clause is used to sort the result set of a query in ascending or descending order based on one or more columns. It is typically placed at the end of a SELECT statement, just before the optional LIMIT or OFFSET clauses.
In the below PDF we discuss about SQL ORDER BY in detail in simple language, Hope this will help in better understanding.
Syntax and Examples :
The basic syntax for the ORDER BY clause is as follows:
SELECT column1, column2, ...
ORDER BY column1 [ASC | DESC], column2 [ASC | DESC], ...;
- column1, column2, …: The columns you want to retrieve in the result set.
- FROM table: The table from which you are retrieving the data.
- ORDER BY: Keyword indicating the start of the sorting specification.
- column1 [ASC | DESC], column2 [ASC | DESC], …: The columns by which you want to sort the result set. ASC (ascending) is the default order, but you can use DESC (descending) for reverse sorting.
Let’s delve into a few examples to illustrate the use of the ORDER BY clause:
1. Sorting with a Single Column:
The simplest use case of ORDER BY involves sorting the result set based on a single column. For instance, if you have a table of products and want to retrieve them in alphabetical order by name, the query would look like this:
SELECT product_name, price
ORDER BY product_name ASC;
In this example, the result set will be sorted in ascending order based on the product_name column.
2. Sorting with Multiple Columns:
The real power of ORDER BY becomes evident when you need to sort by multiple columns. This is useful for scenarios where you want a primary sort on one column and a secondary sort on another. Consider a scenario where you have a table of employees, and you want to sort them first by department and then by salary:
SELECT employee_name, department, salary
ORDER BY department ASC, salary DESC;
In this case, the result set will be sorted in ascending order based on the department column, and within each department, the salary will be sorted in descending order.
3. Sorting NULL Values:
Dealing with NULL values requires special attention when using ORDER BY. By default, NULL values are treated as the highest possible value when sorting in ascending order and the lowest possible value when sorting in descending order. However, you can customize this behavior using the NULLS FIRST or NULLS LAST options:
SELECT column1, column2, ...
ORDER BY column1 [ASC | DESC] NULLS FIRST | NULLS LAST, ...;
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.
The “ORDER BY” clause is typically placed at the end of a SQL query and followed by the column or columns by which you want to sort the result set.
Yes, you can specify multiple columns in the “ORDER BY” clause to sort the result set first by the first column, then by the second column, and so on.
The default sorting order is ascending (ASC) if not explicitly specified. If you want to sort in descending order, you need to use the “DESC” keyword.
Yes, you can combine the “ORDER BY” clause with other clauses like “WHERE” and “GROUP BY” in a SQL query to filter and group data before applying the sorting. The order of clauses in a query is essential for obtaining the desired result.