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Structured Query Language, better known as SQL, has continually established itself as a staple in the world of data sciences. This article focuses on providing hands-on examples highlighting some fundamental SQL functions applicable in Databricks.
1. SELECT Function
The SELECT function is among the most basic, yet essential, SQL operations. It permits data extraction based on specific criteria from a database. A simple SELECT statement looks like this:
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SELECT * FROM Employees |
This SQL snippet retrieves all records from the ‘Employees’ table.
2. WHERE Clause
The WHERE clause is used to filter records meeting particular conditions. For instance, here’s a query that selects entries where ‘Employee_ID’ is 123:
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SELECT * FROM Employees WHERE Employee_ID = 123 |
3. COUNT Function
Perhaps you’re curious about the total number of employees in the company. In that case, you’d use the COUNT function:
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SELECT COUNT(*) FROM Employees |
This will yield the total count of rows present in the ‘Employees’ table, essentially giving the total number of employees.
4. NULL Functions
SQL NULL functions allow you to handle NULL values in expressions. Here is an example of the ISNULL function:
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SELECT ProductName, UnitPrice * (UnitsInStock + ISNULL(UnitsOnOrder, 0)) FROM Products |
In this snippet, ISNULL(UnitsOnOrder, 0) function replaces NULL with 0 if ‘UnitsOnOrder’ is NULL.
Conclusion
These are just a few basic examples of SQL functions and their usage. Databricks offers much more functionality and flexibility in managing and manipulating data using SQL. So, it’s worth experimenting to grasp SQL’s full power within Databricks and adjust it to your needs.
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