The size of each data type in a database can vary depending on the database system you’re using (e.g., MySQL, PostgreSQL, SQL Server, etc.) and the specific data type definitions within that system. Below is a general overview of common data types and their sizes:

1. Integer Types

• TINYINT:
  • Size: 1 byte
  • Range: -128 to 127 (signed), 0 to 255 (unsigned)
• SMALLINT:
  • Size: 2 bytes
  • Range: -32,768 to 32,767 (signed), 0 to 65,535 (unsigned)
• MEDIUMINT (MySQL-specific):
  • Size: 3 bytes
  • Range: -8,388,608 to 8,388,607 (signed), 0 to 16,777,215 (unsigned)
• INT / INTEGER:
  • Size: 4 bytes
  • Range: -2,147,483,648 to 2,147,483,647 (signed), 0 to 4,294,967,295 (unsigned)
• BIGINT:
  • Size: 8 bytes
  • Range: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 (signed), 0 to 18,446,744,073,709,551,615 (unsigned)

2. Floating-Point Types

• FLOAT:
  • Size: 4 bytes
  • Precision: 6-7 decimal digits
• DOUBLE:
  • Size: 8 bytes
  • Precision: 15-16 decimal digits
• REAL:
  • Often an alias for FLOAT or DOUBLE depending on the database system.
  • Size: Depends on the specific implementation.

3. Fixed-Point Types

• DECIMAL / NUMERIC:
  • Size: Varies based on the precision and scale.
  • For example, DECIMAL(10,2) requires approximately 5 bytes.

4. Character Types

• CHAR(n):
  • Size: n bytes (fixed-length)
• VARCHAR(n):
  • Size: Varies based on the actual length of the stored string, plus 1 or 2 bytes for length information.
  • Example: If you store a string of length 10 in VARCHAR(255), the storage requirement is 10 bytes + 1 byte for length = 11 bytes.
• TEXT:
  • Size: Varies depending on the database system.
  • Typically larger, often stored in a different storage area with a reference in the main table.

5. Binary Types

• BINARY(n):
  • Size: n bytes (fixed-length)
• VARBINARY(n):
  • Size: Varies based on the actual length of the stored binary data, plus 1 or 2 bytes for length information.
• BLOB:
  • Size: Varies, depending on the database system.
  • Used for large binary objects, like images or files.

6. Date and Time Types

• DATE:
  • Size: 3 bytes
• TIME:
  • Size: 3 bytes
• DATETIME:
  • Size: 8 bytes
• TIMESTAMP:
  • Size: 4 bytes (in some systems, it might be 8 bytes)
• YEAR (MySQL-specific):
  • Size: 1 byte

7. Boolean Type

• BOOLEAN / BOOL:
  • Size: Typically 1 byte (often stored as TINYINT(1) in MySQL).

8. Other Data Types

• ENUM (MySQL-specific):
  • Size: 1 or 2 bytes, depending on the number of enumeration values.
• SET (MySQL-specific):
  • Size: 1, 2, 3, 4, or 8 bytes, depending on the number of set members.

9. UUID

• UUID:
  • Size: 16 bytes (128 bits)

Notes:

• Database Specifics: The exact size can vary depending on the database system’s internal representation and any additional overhead or optimizations.
• Overhead: Storage sizes mentioned above are for the data itself. Database systems may add additional overhead for indexing, record headers, and other metadata.
• Nullability: If a column allows NULL, some databases add additional storage (e.g., 1 byte) to store the NULL status.