(2) What is the data type of this field now?

My guess: I think these zeros are very neat, and the digits after the decimal point are all the same, indicating that this zero is automatically supplemented. I checked your similar field earlier, and it is also 14 digits after the decimal point (counting digits that are not 0 after the decimal point), which means that I personally think your data type should be mysql Decimal, because it is the only one in the database I know (it is said that it is also available on DB2, but I don't have it).

That is, if your data type is decimal(xx, 14), this will happen. You can use alter to modify the field type of this field, and update can only modify the value of the field, but there is no way to modify the field type of the field. And because of the attribute of decimal(xx, 14), no matter how you update it, it will always be like this.