I believe the answer is that Oracle is very, very old. Back in the olden days before there was a SQL standard, Oracle made the design decision that empty strings in VARCHAR/VARCHAR2 columns were NULL and that there was only one sense of NULL (there are relational theorists that would differentiate between data that has … Read more
In this particular example, I think @Tagir is 100% correct get it into one filter and do the two checks. I wouldn’t use Optional.ofNullable the Optional stuff is really for return types not to be doing logic… but really neither here nor there. I wanted to point out that java.util.Objects has a nice method for … Read more
You should use the Time.IsZero() function instead: func (Time) IsZero or func (t Time) IsZero() bool IsZero reports whether t represents the zero time instant, January 1, year 1, 00:00:00 UTC.
You can use a type predicate function in the .filter to avoid opting out of strict type checking: function notEmpty<TValue>(value: TValue | null | undefined): value is TValue { return value !== null && value !== undefined; } const array: (string | null)[] = [‘foo’, ‘bar’, null, ‘zoo’, null]; const filteredArray: string[] = array.filter(notEmpty); Alternatively … Read more
The expression stringexpression = ” yields: TRUE .. for ” (or for any string consisting of only spaces with the data type char(n)) NULL .. for NULL FALSE .. for anything else So to check for: “stringexpression is either NULL or empty”: (stringexpression = ”) IS NOT FALSE Or the reverse approach (may … Read more
Is null an instance of anything? No, there is no type which null is an instanceof. 15.20.2 Type Comparison Operator instanceof RelationalExpression: RelationalExpression instanceof ReferenceType At run time, the result of the instanceof operator is true if the value of the RelationalExpression is not null and the reference could be cast to the ReferenceType without … Read more
Query A is the same as: select ‘true’ where 3 = 1 or 3 = 2 or 3 = 3 or 3 = null Since 3 = 3 is true, you get a result. Query B is the same as: select ‘true’ where 3 <> 1 and 3 <> 2 and 3 <> null When … Read more
It’s not data that is null, but dataList. You need to create one with public List<Object> dataList = new List<Object>(); Even better: since it’s a field, make it private. And if there’s nothing preventing you, make it also readonly. Just good practice. Aside The correct way to check for nullity is if(data != null). This … Read more
SELECT CASE WHEN field IS NULL THEN ‘Empty’ ELSE field END AS field_alias Or more idiomatic: SELECT coalesce(field, ‘Empty’) AS field_alias
Your question is based on assumption that the code which may throw NullPointerException is worse than the code which may not. This assumption is wrong. If you expect that your foobar is never null due to the program logic, it’s much better to use Optional.of(foobar) as you will see a NullPointerException which will indicate that … Read more