Bits of .NET

Storing 2-letter country codes as VARCHAR(50)? Use CHAR for fixed-length data to optimize storage.

When to Use CHAR:

-- Always exactly 2 characters
CountryCode CHAR(2)  -- 'US', 'UK', 'FR'

-- Always exactly 1 character  
IsActive CHAR(1)  -- 'Y' or 'N'

-- Fixed format
PhoneArea CHAR(3)  -- '555', '212', '415'

When to Use VARCHAR:

-- Variable length
Name VARCHAR(100)  -- Could be 'John' (4 chars) or 'Alexander' (9 chars)
Email VARCHAR(255)
Description VARCHAR(MAX)

Storage Difference:

-- 1 million rows storing 'US'
VARCHAR(50): 1M × 50 bytes = 50 MB
CHAR(2): 1M × 2 bytes = 2 MB

-- 25x less space with CHAR!