MySQL: What's the difference between float and double?

mysql
janpio picture janpio · Jan 29, 2010 · Viewed 133k times · Source

Checking in the new database structure I saw that someone changed a field from float to double. Wondering why, I checked the mysql documentation, but honestly didn't understand what the difference is.

Can someone explain?

Answer

Daniel Vassallo picture Daniel Vassallo · Jan 29, 2010

They both represent floating point numbers. A FLOAT is for single-precision, while a DOUBLE is for double-precision numbers.

MySQL uses four bytes for single-precision values and eight bytes for double-precision values.

There is a big difference from floating point numbers and decimal (numeric) numbers, which you can use with the DECIMAL data type. This is used to store exact numeric data values, unlike floating point numbers, where it is important to preserve exact precision, for example with monetary data.

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