14.1 Understanding SQL Data Types

Every column in a database table must be assigned a Data Type. This tells the DBMS what kind of data is allowed in that column and how much space to allocate.

Common Data Types Category-wise

14.2 Literals in SQL

Literals are the actual constant values used in SQL statements.

1. String Literals: Enclosed in single quotes (e.g., 'Rahul', 'New York').
2. Numeric Literals: Numbers written without quotes (e.g., 100, 3.14, -45).
3. Date Literals: Usually strings in a specific format (e.g., '2023-12-31').
4. NULL Literal: Represents the absence of a value. It is NOT zero or an empty string.

14.3 Choosing the Right Type

• Use VARCHAR instead of CHAR unless the data is ALWAYS the same length (like a Country Code or Gender).
• Use DECIMAL for financial calculations to avoid rounding errors common with FLOAT.