restriction

How would I define a column in PostgreSQL such that each value must be in a sequence, not the sequence you get when using type serial but one such that a value 2 cannot be inserted unless there exists a value 1 already in the column? Theoretically, you could use a constraint that worked like this. (But it won't work in practice.) Count the rows. Evaluate max(column) - min(column) + 1 . Compare the results. You'd probably have to insert one row before creating the CHECK constraint. If you didn't, max(column) would return NULL. With one row, Count the rows (1). Evaluate max(column) - min(column)

I'm using NSOpenPanel to allow a user to select a folder to save documents into. I would like to restrict what folder (in terms of hierarchy) they can save into. Essentially, I want to prevent them from choosing any folder above: /Users/username/ So the folder /Users/username/cats/ would be acceptable but /Users/username/ /Applications/cats/ would not be allowed. I was wondering how to implement this restriction. Thanks. Note that NSOpenPanel inherits from NSSavePanel , which in turn defines a delegate and a corresponding delegate protocol NSOpenSavePanelDelegate . You can use the delegate to

I would like to validate that an element 'Test' should Have its content restricted (for example, using a pattern restriction), and Contain certain attributes (for example, 'id', 'class' and 'name'). The XSD I'm writing looks like this: <xsd:element name="Test" minOccurs="0" maxOccurs="unbounded"> <xsd:complexType mixed="true"> <xsd:simpleContent> <xsd:restriction> <xsd:pattern value="xyz"/> </xsd:restriction> </xsd:simpleContent> <xsd:attribute name="id" type="xsd:string"></xsd:attribute> <xsd:attribute name="class" type="xsd:string"></xsd:attribute> <xsd:attribute name="name" type="xsd:string

Note: This is basically the same question as another one I've posted on Stackoverflow yesterday. However, I figured that I used a poor example in that question that didn't quite boil it down to the essence of what I had in mind. As all replies to that original post refer to that first question I thought it might be a better idea to put the new example in a separate question — no duplication intended. Model Game Characters That Can Move Let's define an enum of directions for use in a simple game: enum Direction { case up case down case left case right } Now in the game I need two kinds of

I have problem with CROSS APPLY with parametrised table valued function. Here is simplified pseudo code example: SELECT * FROM ( SELECT lor.* FROM LOT_OF_ROWS_TABLE lor WHERE ... ) AS lor CROSS APPLY dbo.HeavyTableValuedFunction(lor.ID) AS htvf INNER JOIN ANOTHER_TABLE AS at ON lor.ID = at.ID WHERE ... Inner select on table LOT_OF_ROWS_TABLE is returning many rows. Joining tables LOT_OF_ROWS_TABLE and ANOTHER_TABLE returns only one or few rows. Table valued function is very time consuming and when calling for a lot of rows the select lasts very long time. My problem: The function is called for