Re: counting days in a query

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Date: Fri, 26 Dec 2003 22:00:04 +0100

"Ike" wrote...
> How can I make a query such that in the "WHERE" part
> of my clause, I want to put something to the effect
> that, say, X days have elapsed since a given date.

This is not a Java-related question, and you should try to ask such
questions in a database-specific group.

> For example, suppose in my table, I have a boolean
> field and a date field. I want to create a query
> asking for those rows where X days have elapsed
> from the date field in a row and the boolean, say, is false.

Most databases has built-in-functions to compare dates, but in most cases
they are database-specific. When you ask such questions, please also make a
note on which database you're using. If the database conforms to SQL99, I
don't even think that you need special date-functions.

> Do I need to create a third field, called, say "X"
> for how many days have elapsed between the date field
> and today, and update every row in the table
> every day?

No, this should in most cases not be necessary, but you'll have to look up
in the documentation for the specific database how the Date- and
Boolean-types are implemented, and which functions you need for the query.

Just an example, not db-specific and probably wrong for most databases:

  SELECT *
  FROM myTable
  WHERE (CURRENT_DATE - myDateField) >= 10
  AND myBooleanField = TRUE;

// Bjorn A

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