   FLOAT(p) [UNSIGNED] [ZEROFILL]

A floating-point number.  p represents the precision. It can be from
0 to 24 for a single-precision floating-point number and from 25 to 53 for a
double-precision floating-point number. These types are like the FLOAT
and DOUBLE types described immediately following.  FLOAT(p)
has the same range as the corresponding FLOAT and DOUBLE
types, but the display width and number of decimals are undefined.

As of MySQL 3.23, this is a true floating-point value.  In
earlier MySQL versions, FLOAT(p) always has two decimals.

This syntax is provided for ODBC compatibility.

Using FLOAT might give you some unexpected problems because
all calculations in MySQL are done with double precision.
See also : [No matching rows].

   FLOAT[(M,D)] [UNSIGNED] [ZEROFILL]

A small (single-precision) floating-point number.  Allowable values are
-3.402823466E+38 to -1.175494351E-38, 0,
and 1.175494351E-38 to 3.402823466E+38.  If UNSIGNED is
specified, negative values are disallowed.  M is the display width and
D is the number of significant digits. FLOAT without arguments or
FLOAT(p) (where p is in the range from 0 to 24) stands for a
single-precision floating-point number.
