The ROW_NUMBER() function in SQLite is a window function that assigns a unique sequential number to each row within a specified result set. This function is often used to generate row numbers or rankings for a particular set of data.
The syntax for using the ROW_NUMBER() function in SQLite is as follows:
SELECT ROW_NUMBER() OVER (ORDER BY column_name) as row_num, column1, column2, ... FROM table_name;
In this syntax, ROW_NUMBER() is the function call that generates the row numbers, while OVER (ORDER BY column_name) defines the window for the function, where column_name specifies the column used for ordering the rows. The AS row_num clause is used to assign a name to the generated column.
It is important to note that the ROW_NUMBER() function does not modify the original data in any way, but rather adds a new column to the result set with the assigned row numbers.
Here’s an example of how the ROW_NUMBER() function can be used in SQLite:
Suppose we have a table named “employees” with columns “employee_id”, “employee_name”, and “salary”. We can use the ROW_NUMBER() function to generate row numbers based on the employee’s salary in descending order as follows:
SELECT ROW_NUMBER() OVER (ORDER BY salary DESC) as row_num, employee_name, salary FROM employees;
The above query will generate a result set that assigns a unique row number to each employee based on their salary, where the employee with the highest salary will be assigned a row number of 1, the employee with the second-highest salary will be assigned a row number of 2, and so on.
In summary, the ROW_NUMBER() function is a powerful tool for generating row numbers or rankings in SQLite, and can be easily used in combination with other SQL functions to manipulate and analyze data.