What common mistake do developers make with Grouping, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Grouping, why does the mistake cause problems, and what is the safer approach? One recurring problem with grouping is applying it without understanding the boundary it protects. Concatenating request parameters into raw SQL expressions instead of passing values through the query builder bindings. In addition, Group-by queries aggregate rows by one or more columns. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.