如何插入NULL long值？

Question

I have a database made up a single table with several fields, one of which is a phone number that is stored as a NUMERIC. Because the phone number is 10 digits, in my code I have captured the variable as a LONG.

My question is, in the insert statement, how do I pass a NULL value? Is this possible at all? I can't assign a null value to the LONG variable, so I'm wondering how to go about doing this...

Answer 1

Because the phone number is 10 digits, in my code I have captured the variable as a LONG.

Bad idea. Phone numbers might look like numbers, but they're not. They're strings of characters that happen to be mostly digits. But they can also contain symbols such as + .

Use a String instead.

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Update: If you are required to use a numeric type then make sure you use Long instead of long . The capitilazation is important. And by the way, there is no such type as LONG in standard Java.

Answer 2

If you desperately need to use numerics for the phone number, why not just code a non-existing phone number into something like 0L or -1L?

Edit: Btw, you say that the database is limited to numeric format. Does the same go for the java side?

long dbPhoneNumber = getTheLongFieldFromTheDatabase();
String internalPhoneNumberRepresentation = Long.toString(dbPhoneNumber);
doSomethingWithString();
dbPhoneNumber = internalPhoneNumberRepresentation == null ? 0L : internalPhoneNumberRepresentation;
storeLongFieldToDatabase(dbPhoneNumber);

Should more or less do all you need, right?

Answer 3

First of all, why do you store a phone number as a numeric field? In most cases you probably also want to store things like "+41 (52) 123 455", which you loose with numeric datatypes, but ok.

Then for inserting null values: What about:

INSERT INTO mytable (phone) VALUES (NULL);