# Select Data Types
__*ABC Principles*__
+ `ABC` Principles:
  + `Appropriate`: Appropriate
  + `Brief`: Minimal resource consumption
  + `Complete`: Data cannot be lost
+ Design and consideration of primary keys

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- Ensure that the data type of the column is appropriate, short, and complete:
  - Appropriate: Select the most appropriate data type for the data contained in the column.
  - Short: Select the type of data that uses the least amount of storage space. This saves resources and improves performance.
  - Complete: Ensures that the data type can store as large a value as possible for each column without losing data.

Each table should have a primary key so that each row can be uniquely identified later. Integers are the most efficient for processing as primary keys.

Within each data type, there are many subtypes that consume varying amounts of memory and disk space and affect performance. This is important for large databases. Make the right decisions early in the design process to avoid performance issues later on.