How can I check with a SQL query that a field has a given rounding?

[jules]

What query to check that the values in a column are rounded, for example, to 3 decimal places? Or Inverse query that there are no values other than three-digit rounding.

[Analeea]

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))