Bits of .NET

📊 Data Types = Performance

Wrong data types hurt performance. Choose the right data types — storage, speed, accuracy. Essential for database design.

📝 Numeric Data Types

# Integer Types
TINYINT   → 0 to 255 (1 byte)
SMALLINT  → -32,768 to 32,767 (2 bytes)
MEDIUMINT → -8,388,608 to 8,388,607 (3 bytes)
INT       → -2.1B to 2.1B (4 bytes)
BIGINT    → -9.2B to 9.2B (8 bytes)

# Decimal Types
DECIMAL(10,2) → 10 digits, 2 decimals
NUMERIC(10,2) → Same as DECIMAL
FLOAT         → Approximate, 4 bytes
DOUBLE        → Approximate, 8 bytes

# When to Use
INT          → Ids, counts
BIGINT       → Large numbers
DECIMAL(10,2) → Money
FLOAT        → Scientific, approximate

# Example
CREATE TABLE orders (
    id INT PRIMARY KEY AUTO_INCREMENT,
    total_amount DECIMAL(10,2) NOT NULL,
    quantity INT NOT NULL,
    discount_rate FLOAT
);

🎯 String and Date Types

# String Types
CHAR(n)       → Fixed length (1-255)
VARCHAR(n)    → Variable length (1-65535)
TEXT          → Max 65,535 bytes
MEDIUMTEXT    → Max 16,777,215 bytes
LONGTEXT      → Max 4,294,967,295 bytes

# Binary Types
BINARY(n)     → Fixed binary
VARBINARY(n)  → Variable binary
BLOB          → Max 65,535 bytes
MEDIUMBLOB    → Max 16,777,215 bytes
LONGBLOB      → Max 4,294,967,295 bytes

# Date Types
DATE          → YYYY-MM-DD
TIME          → HH:MM:SS
DATETIME      → YYYY-MM-DD HH:MM:SS
TIMESTAMP     → Unix timestamp
YEAR          → Year (4 digits)

# When to Use
VARCHAR(50)   → Short text (names, emails)
VARCHAR(255)  → Medium text
TEXT          → Long text (articles)
CHAR(1)       → Fixed values (gender: 'M','F')
DATETIME      → Creation date
TIMESTAMP     → Last updated

# Example
CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    email VARCHAR(255) UNIQUE NOT NULL,
    bio TEXT,
    gender CHAR(1),
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

# Data Type Tips
- Choose the smallest adequate type
- Use VARCHAR over TEXT when possible
- Use DECIMAL for money (avoid FLOAT)
- Use TIMESTAMP for last updated
- Index types affect performance

💡 Data Type Tips

• Choose the smallest adequate type
• Use VARCHAR over TEXT when possible
• Use DECIMAL for money (avoid FLOAT)
• Use TIMESTAMP for last updated
• Index types affect performance