MySQL Manual
6 MySQL Language Reference
- 6.2 Column Types
- 6.2.1 Numeric Types
- 6.2.2 Date and Time Types
- 6.2.3 String Types
- 6.2.4 Choosing the Right Type for a Column
- 6.2.5 Using Column Types from Other Database Engines
- 6.2.6 Column Type Storage Requirements
6.2.4 Choosing the Right Type for a Column
For the most efficient use of storage, try to use the most precise type in
all cases. For example, if an integer column will be used for values in the
range between 1 and 99999, MEDIUMINT UNSIGNED is the
best type.
Accurate representation of monetary values is a common problem. In
MySQL, you should use the DECIMAL type. This is stored as
a string, so no loss of accuracy should occur. If accuracy is not
too important, the DOUBLE type may also be good enough.
For high precision, you can always convert to a fixed-point type stored
in a BIGINT. This allows you to do all calculations with integers
and convert results back to floating-point values only when necessary.
