PL/SQL, like SQL, is case insensitive. The general guidelines here are as follows:
Use uppercase for keywords (BEGIN, EXCEPTION, END, IF THEN ELSE, LOOP, END LOOP, etc.), datatypes (VARCHAR2, NUMBER), built-in functions (LEAST, SUBSTR, etc.), and user-defined subroutines (procedures, functions, packages).
Use lowercase for variable names as well as column and table names in SQL.
White space (extra lines and spaces) is as important in PL/SQL as it is in SQL. It is a main factor in providing readability. In other words, you can reveal the logical structure of the program by using indentation in your code. Here are some suggestions:
Put spaces on both sides of an equality ...