SQL Clean Code in SQL Indenting
Example
There is no widely accepted standard. What everyone agrees on is that squeezing everything into a single line is bad:
SELECT d.Name, COUNT(*) AS Employees FROM Departments AS d JOIN Employees AS e ON d.ID = e.DepartmentID WHERE d.Name != 'HR' HAVING COUNT(*) > 10 ORDER BY COUNT(*) DESC;
At the minimum, put every clause into a new line, and split lines if they would become too long otherwise:
SELECT d.Name,
COUNT(*) AS Employees
FROM Departments AS d
JOIN Employees AS e ON d.ID = e.DepartmentID
WHERE d.Name != 'HR'
HAVING COUNT(*) > 10
ORDER BY COUNT(*) DESC;
Sometimes, everything after the SQL keyword introducing a clause is indented to the same column:
SELECT d.Name,
COUNT(*) AS Employees
FROM Departments AS d
JOIN Employees AS e ON d.ID = e.DepartmentID
WHERE d.Name != 'HR'
HAVING COUNT(*) > 10
ORDER BY COUNT(*) DESC;
(This can also be done while aligning the SQL keywords right.)
Another common style is to put important keywords on their own lines:
SELECT
d.Name,
COUNT(*) AS Employees
FROM
Departments AS d
JOIN
Employees AS e
ON d.ID = e.DepartmentID
WHERE
d.Name != 'HR'
HAVING
COUNT(*) > 10
ORDER BY
COUNT(*) DESC;
Vertically aligning multiple similar expressions improves readability:
SELECT Model,
EmployeeID
FROM Cars
WHERE CustomerID = 42
AND Status = 'READY';
Using multiple lines makes it harder to embed SQL commands into other programming languages.
However, many languages have a mechanism for multi-line strings, e.g., @"..." in C#, """...""" in Python, or R"(...)" in C++.
