SQL Style Guide

— by Dat Le on 23th Feb 2017

Consistent SQL style would help a lot in code review and development process, especially when SQL is the main language we use in the data team at honestbee.

Below are all the rules and conventions:

Formatting

• All keywords need to be capitalized, it helps with readability, even if no syntax highlighting available.
• Proper indentation is also important for code readability
• Table references should always be used when more than one table is referred in a query
• Avoid using alias unless absolutely necessary, naming should be underscore-separated

JOINS

• Always specify which JOIN function to use, either LEFT JOIN, RIGHT JOIN,INNER JOIN, and so on…
• LEFT JOIN should mainly be used when applicable
• Starts with the deepest level of data (i.e with the most number of rows)

Sub Queries & Aggregations

• Common Table Expressions (CTEs) or Temporary Tables should be used instead of Sub Queries
• Aggregation functions should only be used on columns that are necessary