Statements and structure
A SQL program is a list of statements that the computer executes one after another. The language has strict rules — called syntax — about how those statements must be written. Get the syntax slightly wrong and the program will refuse to run. The good news is the rules are small and consistent: once you have learned the basic shape of a statement you can read almost any SQL program.
Comments
Comments are notes for humans that the computer ignores. Use them generously to explain why your code does something, not what it does. Future-you (and your teammates) will thank you.
SELECT 'Hello, World!' AS greeting;Case sensitivity and whitespace
SQL is case sensitive — Total and total are two different names. Indentation makes code readable; in some languages it is purely cosmetic and in others (like Python) it is part of the syntax. Always indent the body of a block.