It’s always important to know the fundamentals of SQL before writing or executing any SQL query. So, you must familiarize with the concepts covered in this chapter.

• 1.3.1 Schema Objects
• 1.3.2 Data Types
• 1.3.3 Operators
• 1.3.4 Literals
• 1.3.5 Variables
• 1.3.6 Constants
• 1.3.7 Substitution Variables
• 1.3.8 NULL in Oracle