Overview
In databases, empty and null values may look similar but have different meanings. An empty value means an empty string ('') is stored in a column, especially in string-type fields. Understanding this difference is crucial, as the concept is used in Blanks and Value Range Rule checks. A null means no value has been stored—you'll see it NULL explicitly written in the database.
1. Understanding the concept of Empty Strings
Before jumping into the application, let's try to understand the concept directly from the database. Here, we have a column named "capital", and we can see that empty strings are stored in it—these are empty values:
Now, if we check the same column in the application, we can see that the "capital" column has some empty values.
If we apply the Blanks Rule with the "Empty" checkbox selected, 4 exceptions are expected. Navigate to the Blanks Rule and apply this check.
Note: Selecting at least one of the checkboxes is necessary to save the Blanks Rule.
After saving and running the rule, the number of exceptions will be 4, which is the expected result.
This same check for empty strings can also be used in the Value Range Rule, and the concept remains the same as explained above.
2. Understanding the concept of Nulls
Now, let’s consider the same "capital" column. In the database, we can see entries where it [NULL] is mentioned—these are the null values.
From the profiling information in the application, we can see that the "capital" column also has some null values.
If we apply the Blanks Rule with the "Null" checkbox selected, the expected number of exceptions will be 284.
As shown earlier, the same check is available in the Value Range Rule, and the concept is identical. In the Ruleset Rule, both Blanks and Value Range checks are available, and the logic remains the same.
Additional Resources
To better understand the context of this article, it’s essential to be familiar with the following rules, as they are used when applying blank and null checks:
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