There is already a separate entry for “FLOAT, DOUBLE, and DECIMAL” and “ENUM”. A single page on datatypes is likely to be unwieldy – I suggest “Field types” (or should it be called “Datatypes”?) be an overview, then split into these topic pages:

• INTs
• FLOAT, DOUBLE, and DECIMAL
• Strings (CHARs, TEXT, etc)
• BINARY and BLOB
• DATETIME, TIMESTAMP, and friends
• ENUM and SET
• Spatial data
• JSON type (MySQL 5.7.8+)
• How to represent Money, and other common ‘types’ that need shoehorning into existing datatypes

Where appropriate, each topic page should include, in addition to syntax and examples:

• Considerations when ALTERing
• Size (bytes)
• Contrast with non-MySQL engines (low priority)
• Considerations when using the datatype in a PRIMARY KEY or secondary key
• other Best Practice
• other Performance issues

(I assume this “example” will self-distruct when my suggestions have been satisfied or vetoed.)