If we mean a table field, then
SELECT column_name,
data_type,
numeric_precision,
numeric_scale
FROM information_schema.columns
WHERE table_schema = 'database'
AND table_name = 'table'
AND data_type IN ('decimal','float','double');
If we are talking about a field in a certain data set, then in the general case, no way
How using a query you can parse a string and count the characters after the decimal point
(LOCATE(SUBSTRING(1.1 FROM 2 FOR 1), field) > 0) * LENGTH(SUBSTRING_INDEX(field, SUBSTRING(1.1 FROM 2 FOR 1), -1))
If you are convinced that tricks with a decimal separator are not expected, then simply do the following:
(LOCATE('.', field) > 0) * LENGTH(SUBSTRING_INDEX(field, '.', -1))
