I need to make a manual test plan (black box testing) to see whether a value is hard coded in a drop down list (its' the acceptance criteria). Can anybody give me any suggestions on that?

We're in the designing phase. We are extracting the date using API calls and storing the extracted data in Azure SQL Server and i wanted to test whether the exact data is loading in azure or not.

Create a script for them too?

One is enough for a start. At least for a start.

Maybe I'm doing something wrong?

You are doing everything right. Only in the Controller module you need to set the number of virtual users.

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))