Trying to help a friend out here. I'm not a Microsoft programmer.
public abstract class Foo {}
public class Bar : Foo {}
public class Baz : Foo {}
This seems to work pretty well then in another class he can instantiate arrays of Bar, and Baz like this
public class MyClass {
Bar[] Bars = new...
As the title suggests, is possible to concatenate the 2 without converting the the data types...
DECLARE @test VARCHAR(50) = 'Hello World!'
DECLARE @testvb VARBINARY(256)
SET @testvb = CAST(@test AS VARBINARY(256));
SELECT @test + @testvb --dont want to cast this back to var char
SQL Server instances on dbfiddle create a new database for every execution, could they just use tempdb instead? I mean is there anything (useful) you can't do in tempdb that you can do in a dedicated database?
@JackDouglas maybe the database could be created once at the beginning of a user session, then dropped after some timeout? That would decrease the I/O requirement, and speed up each execution. Just a thought.
It says here: "Any user can create temporary objects in tempdb. Users can only access their own objects, unless they receive additional permissions." — I assumed that meant each session effectively gets it's own tempdb namespace
correct. the name of the #temp table is scoped to your session, whereas the name of any constraints where you define the name of the constraint must be unique across all sessions.
you'd have to uniquify them manually; which would be a nightmare.
the standard way around that is to not explicitly name constraints for objects in tempdb. If you don't specify a constraint name, SQL Server generates one automatically, and it's unique.
This can only happen if the same client connection instantiation (which equals one SPID or connection in SQL Server) is being re-used for 2 different calls. Two parallel calls should have different connection instantiations and separate SPIDs
SPIDs are completely isolated from each other with lo...
when I complained about use master throwing the weird error message
I wanted a proper error message
not for it to work
Msg 916 Level 14 State 1 Line 1 The server principal "fiddle_401cd1359db24148a13fbfecaab29641" is not able to access the database "model" under the current security context.
imo that is what should happen with the other three
I didn't answer your question because I'm pretty unknowledgeable when it comes to security
I'm not sure if this is a known issue: dbfiddle.uk/… returns "22P02ERROR: invalid input syntax for type json DETAIL: The input string ended unexpectedly. CONTEXT: JSON data, line 1: "
@JoeObbish thanks, 'fixed' in that I'm now returning something rather than crashing. If the driver thinks the return type is 'unknown' I return it as hex now. I think the Windows SQL Server instances are going to work better than the Linux version simply because the drivers are better — I might add a vNext Windows variant at some point.
@Marcus nice analysis. I've edited the answer - just a bit - and reverted my vote ;)
To @mods. Can I delete my comments from the question now - that they are in the chat room? I'm always hesitant, fearing they might be deleted from the chat, too.
@ypercubeᵀᴹ I don't believe there's any link between comments and their chat room copies like that. Mods often move long discussions to chat by creating a chat room containing all the comments and removing the (original) comments.
@Philᵀᴹ I don't think it's possible — all I can do is secure the central VM, not the DB backends. Oracle XE gets no patches at all as you no doubt know.
If you have a table with a composite key, where one column is a Type to ensure that only entities of the right type are in the table, do you just put the FK relationship with the composite key, or do you also do an FK for the Type to the Type table? For example...
I guess I should ask the question, but it's kind of subjective perhaps
CREATE TABLE WidgetType(WidgetTypeId int identity(1,1) NOT NULL PK, WidgetType varchar(100));
CREATE TABLE Widget(
WidgetId int identity(1,1) NOT NULL PK,
WidgetTypeId int NOT NULL CONSTRAINT FK_Widget_WidgetType FOREIGN KEY REFERENCES WidgetType(WidgetTypeId),
WidgetName varchar(100)
)
CREATE TABLE WidgetRel(
ParentWidgetTypeId int NOT NULL,
ParentWidgetId int NOT NULL,
ChildWidgetTypeId int NOT NULL,
ChildWidgetId int NOT NULL,
CONSTRAINT FK_Widget_Parent FOREIGN KEY (ParentWidgetTypeId, ParentWidgetId) REFERENCES Widget (WidgetTypeId, WidgetId),
CONSTRAINT FK_Widget_Child FOREIGN KEY (ChildWidgetTypeId, ChildWidgetId) REFERENCES Widget (WidgetTypeId, WidgetId),
CONSTRAINT CK_ParentWidgetTypeIsFrob CHECK (ParentWidgetTypeId = 1),
CONSTRAINT CK_ChildWidgetTypeIsGlob CHECK (ChildWidgetTypeId = 2)
In table WidgetRel, would you also make an FK from ParentWidgetTypeId to WidgetType (and for Child as well) or simply trust that because of the chained FK relationship there is no need?
For completeness:
SET IDENTITY_INSERT WidgetType ON;
INSERT WidgetType(WidgetTypeId, WidgetType) VALUES (1, 'Frob'), (2, 'Glob');
SET IDENTITY_INSERT WidgetType OFF;
Feel free to recommend I ask the question as a real question
As the title suggests, is possible to concatenate the 2 without converting the the data types...
DECLARE @test VARCHAR(50) = 'Hello World!'
DECLARE @testvb VARBINARY(256)
SET @testvb = CAST(@test AS VARBINARY(256));
SELECT @test + @testvb --dont want to cast this back to var char
So basically I was wondering how are queries optimized through the use of Relational Algebra and/or Relational Calculus.
Please be clear :)
