MYSQL FLOAT

[uaoleg]

Perhaps this example could explain.

CREATE TABLE test(fla FLOAT,flb FLOAT,dba DOUBLE(10,2),dbb DOUBLE(10,2));
We have a table like this:

+-------+-------------+
| Field | Type |
+-------+-------------+
| fla | float |
| flb | float |
| dba | double(10,2)|
| dbb | double(10,2)|
+-------+-------------+
For first difference, we try to insert a record with '1.2' to each field:

INSERT INTO test values (1.2,1.2,1.2,1.2);
The table showing like this:

SELECT * FROM test;

+------+------+------+------+
| fla | flb | dba | dbb |
+------+------+------+------+
| 1.2 | 1.2 | 1.20 | 1.20 |
+------+------+------+------+
See the difference?

We try to next example:

SELECT fla+flb, dba+dbb FROM test;
Hola! We can find the difference like this:

+--------------------+---------+
| fla+flb | dba+dbb |
+--------------------+---------+
| 2.4000000953674316 | 2.40 |
+--------------------+---------+

Source: https://stackoverflow.com/a/28511784/676479