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  • SQL SERVER – Validating Spatial Object as NULL using IsNULL

    - by pinaldave
    Follow up questions are the most fun part of writing a blog post. Earlier I wrote about SQL SERVER – Validating Spatial Object with IsValidDetailed Function and today I received a follow up question on the same subject. The question was mainly about how NULL is handled by spatial functions. Well, NULL is NULL. It is very easy to work with NULL. There are two different ways to validate if the passed in the value is NULL or not. 1) Using IsNULL Function IsNULL function validates if the object is null or not, if object is not null it will return you value 0 and if object is NULL it will return you the value NULL. DECLARE @p GEOMETRY = 'Polygon((2 2, 3 3, 4 4, 5 5, 6 6, 2 2))' SELECT @p.ISNULL ObjIsNull GO DECLARE @p GEOMETRY = NULL SELECT @p.ISNULL ObjIsNull GO 2) Using IsValidDetailed Function IsValidateDetails function validates if the object is valid or not. If the object is valid it will return 24400: Valid but if the object is not valid it will give message with the error number. In case object is NULL it will return the value as NULL. DECLARE @p GEOMETRY = 'Polygon((2 2, 3 3, 4 4, 5 5, 6 6, 2 2))' SELECT @p.IsValidDetailed() IsValid GO DECLARE @p GEOMETRY = NULL SELECT @p.IsValidDetailed() IsValid GO When to use what? Now you can see that there are two different ways to validate the NULL values. I personally have no preference about using one over another. However, there is one clear difference between them. In case of the IsValidDetailed Function the return value is nvarchar(max) and it is not always possible to compare the value with nvarchar(max). Whereas the ISNULL function returns the bit value of 0 when the object is null and it is easy to determine if the object is null or not in the case of ISNULL function. Additionally, ISNULL function does not check if the object is valid or not and will return the value 0 if the object is not NULL. Now you know even though either of the function can be used in place of each other both have very specific use case. Use the one which fits your business case. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Spatial Database, SQL Spatial

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  • Matt Asay on Partisanship

    <b>The-Source.com:</b> "If Microsoft warms up to open source, why not share some plaudits? And even when it gets things wrong, surely it&#8217;s better to politely critique rather than spew invectives?"

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  • C++ segmentation error when first parameter is null in comparison operator overload

    - by user1774515
    I am writing a class called Word, that handles a c string and overloads the <, , <=, = operators. word.h: friend bool operator<(const Word &a, const Word &b); word.cc: bool operator<(const Word &a, const Word &b) { if(a == NULL && b == NULL) return false; if(a == NULL) return true; if(b == NULL) return false; return a.wd < b.wd; //wd is a valid c string } main: char* temp = NULL; //EDIT: i was mistaken, temp is a char pointer Word a("blah"); //a.wd = [b,l,a,h] cout << (temp<a); i get a segmentation error before the first line of the operator< method after the last line in the main. I can correct the problem by writing cout << (a>temp); where the operator> is similarly defined and i get no errors. but my assignment requires (temp < a) to work so this is where i ask for help. EDIT: i made a mistake the first time and i said temp was of type Word, but it is actually of type char*. so i assume that the compiler converts temp to a Word using one of my constructors. i dont know which one it would use and why this would work since the first parameter is not Word. here is the constructor i think is being used to make the Word using temp: Word::Word(char* c, char* delimeters=NULL) { char *temporary = "\0"; if(c == NULL) c = temporary; check(stoppers!=NULL, "(Word(char*,char*))NULL pointer"); //exits the program if the expression is false if(strlen(c) == 0) size = DEFAULT_SIZE; //10 else size = strlen(c) + 1 + DEFAULT_SIZE; wd = new char[size]; check(wd!=NULL, "Word(char*,char*))heap overflow"); delimiters = new char[strlen(stoppers) + 1]; //EDIT: changed to [] check(delimiters!=NULL,"Word(char*,char*))heap overflow"); strcpy(wd,c); strcpy(delimiters,stoppers); count = strlen(wd); } wd is of type char* thanks for looking at this big question and trying to help. let me know if you need more code to look at

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  • Dereferencing the null pointer

    - by zilgo
    The standard says that dereferencing the null pointer leads to undefined behaviour. But what is "the null pointer"? In the following code, what we call "the null pointer": struct X { static X* get() { return reinterpret_cast<X*>(1); } void f() { } }; int main() { X* x = 0; (*x).f(); // the null pointer? (1) x = X::get(); (*x).f(); // the null pointer? (2) x = reinterpret_cast<X*>( X::get() - X::get() ); (*x).f(); // the null pointer? (3) (*(X*)0).f(); // I think that this the only null pointer here (4) } My thought is that dereferencing of the null pointer takes place only in the last case. Am I right? Is there difference between compile time null pointers and runtime according to C++ Standard?

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  • sql query where parameters null not null

    - by Laziale
    I am trying to do a sql query and to build the where condition dynamically depending if the parameters are null or no. I have something like this: SELECT tblOrder.ProdOrder, tblOrder.Customer FROM tblOrder CASE WHEN @OrderId IS NOT NULL THEN WHERE tblOrder.OrderId = @OrderId ELSE END CASE WHEN @OrderCustomer IS NOT NULL THEN AND tblOrder.OrderCustomer = @OrderCustomer ELSE END END This doesn't work, but this is just a small prototype how to assemble the query, so if the orderid is not null include in the where clause, or if the ordercustomer is not null include in the where clause. But I see problem here, for example if the ordercustomer is not null but the orderid is null, there will be error because the where keyword is not included. Any advice how I can tackle this problem. Thanks in advance, Laziale

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  • IS NULL vs = NULL in where clause + SQL Server

    - by Nev_Rahd
    Hello How to check a value IS NULL [or] = @param (where @param is null) Ex: Select column1 from Table1 where column2 IS NULL => works fine If I want to replace comparing value (IS NULL) with @param. How can this be done Select column1 from Table1 where column2 = @param => this works fine until @param got some value in it and if is null never finds a record. How can this achieve?

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  • IS NULL vs = NULL in where clause + MSSQL

    - by Nev_Rahd
    Hello How to check a value IS NULL [or] = @param (where @param is null) Ex: Select column1 from Table1 where column2 IS NULL = works fine If I want to replace comparing value (IS NULL) with @param. How can this be done Select column1 from Table1 where column2 = @param = this works fine until @param got some value in it and if is null never finds a record. How can this achieve?

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  • inserting or updating values into null textboxes [closed]

    - by tanya
    this is my sql table structure create table cottonpurchase ( slipNo int null, purchasedate datetime, farmercode int , farmername varchar (100), villagename varchar (100), basicprice int null, premium int null, totalamountpaid int null, weight int null, totalamountbasic int null, totalamountpremium int null, Yeildestimates int null ) I want to fill in the null values in my sql with actual values and not leave them null but I want to do that from my winforms app form! But if I do that it just adds a new record when what I want is for it to update the record which has, for example, farmercode = 2, farmername = blaah, and so on. I also want to enter this in the same records as in farmercode = 2 and the corresponding corresponding basic price = ... , everytime i do it it ends up making a new record and not in the existing one.

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  • Sql Server Where Case Then Is Null Else Is Not Null

    - by Fabio Montezuma
    I have a procedure which receive a bit variable called @FL_FINALIZADA. If it is null or false I want to restrict my select to show only the rows that contain null DT_FINALIZACAO values. Otherwise I want to show the rows containing not null DT_FINALIZACAO values. Something like this: SELECT * FROM ... WHERE ... AND (OPE.DT_FINALIZACAO = CASE WHEN (@FL_FINALIZADA <> 1) THEN NULL END OR OPE.DT_FINALIZACAO IS NOT NULL) In this case I receive the message: None of the result expressions in a CASE specification can be NULL. How can I achieve this? Thanks in advance.

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  • Ultrawingrid - how to display #1/1/1800# as blank ( as if null )

    - by Charles Hankey
    Ultrawingrid 9.2 VS2008 .net 3.5 My wingrid uses a bindingsource. All datetimes which are null in SQL Server are delivered to the bindingsource as #1/1/1800# I would like Ultrawingrid to display this date as blank as it would a null from source. Also, if the date is null in the grid ( i.e. blanked out ) I would like to update the data source to the date #1/1/1800# ( the framework takes care of getting that date back into the backend as a null ) This seems like it should be a trivial matter but I can find no documentation on just where to intervene so the grid will see a particular date as a null and save a null as a particular date. This is the direction I've been headed but I don't think either is the right place and I can't even get the syntax to work in the BeforeRowUpdate as I cannot see how to set a value that is passed to the data binding without setting the value of control itself, which I think has to remain null in order to display as blank Private Sub ugPropMaster_BeforeRowUpdate(ByVal sender As Object, ByVal e As _ Infragistics.Win.UltraWinGrid.CancelableRowEventArgs) Handles _ ugPropMaster.BeforeRowUpdate If e.Row.Cells.Item("Exdate").Value Is Nothing Then e.Row.Cells("Exdate").Value = CDate(#1/1/1800#) End If End Sub Private Sub ugPropMaster_InitializeRow(ByVal sender As Object, ByVal e As _ Infragistics.Win.UltraWinGrid.InitializeRowEventArgs) Handles _ ugPropMaster.InitializeRow If CDate(e.Row.Cells.Item("Exdate").Value) = CDate(#1/1/1800#) Then e.Row.Cells.Item("Exdate").Value = Nothing End If End Sub Guidance much appreciated

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  • Managed bean property value not set to null

    - by Vladimir
    Hi! I'm new to JSF, so this question might be strange. I have an inputText component's value bound to managed bean's property of type Float. I need to set property to null when inputText field is empty, not to 0 value. It's not done by default, so I added converter with the following method implemented: public Object getAsObject(FacesContext arg0, UIComponent arg1, String arg2) throws ConverterException { if (StringUtils.isEmpty(arg2)) { return null; } float result = Float.parseFloat(arg2); if (result == 0) { return null; } return result; } I registered converter, and assigned it to inputText component. I logged arg2 argument, and also logged return value from getAsObject method. By my log I can see that it returns null value. But, I also log setter property on backing bean and argument is 0 value, not null as expected. To be more precise, it is setter property is called twice, once with null argument, second time with 0 value argument. It still sets backing bean value to 0. How can I set value to null? Thanks in advance.

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  • Throwing exception vs checking null, for a null argument

    - by dotnetdev
    What factors dictate throwing an exception if argument is null (eg if (a is null) throw new ArgumentNullException() ), as opposed to checking the argument if it is null beforehand. I don't see why the exception should be thrown rather than checking for null in the first place? What benefit is there in the throw exception approach? This is for C#/.NET Thanks

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  • Java - JSON Null Exception

    - by user1112111
    Hi, I'm using JSON to deserialize an input string that contains a null value for certain hashmap property. Does anyone have any clue why this exception occurs ? Is it possible that null is not accepted as a value Is this configurable somehow ? input sample: {"prop1":"val1", "prop2":123, "prop3":null} stacktrace: net.sf.json.JSONException: null object at net.sf.json.JSONObject.verifyIsNull(JSONObject.java:2856) at net.sf.json.JSONObject.isEmpty(JSONObject.java:2212) Thanks.

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  • How can a not null constraint be dropped?

    - by Tomislav Nakic-Alfirevic
    Let's say there's a table created as follows: create table testTable ( colA int not null ) How would you drop the not null constraint? I'm looking for something along the lines of ALTER TABLE testTable ALTER COLUMN colA DROP NOT NULL; which is what it would look like if I used PostgreSQL. To my amazement, as far as I've been able to find, the MySQL docs, Google and yes, even Stackoverflow (in spite of dozens or hundreds of NULL-related questions) don't seem to lead towards a single simple SQL statement which will do the job.

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  • Negate the null-coalescing operator

    - by jhunter
    I have a bunch of strings I need to use .Trim() on, but they can be null. It would be much more concise if I could do something like: string endString = startString !?? startString.Trim(); Basically return the part on the right if the part on the left is NOT null, otherwise just return the null value. I just ended up using the ternary operator, but is there anyway to use the null-coalescing operator for this purpose?

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  • Why cast null before checking if object is equal to null?

    - by jacerhea
    I was looking through the "Domain Oriented N-Layered .NET 4.0 Sample App" project and ran across some code that I do not understand. In this project they often use syntax like the following to check arguments for null: public GenericRepository(IQueryableContext context,ITraceManager traceManager) { if (context == (IQueryableContext)null) throw new ArgumentNullException("context", Resources.Messages.exception_ContainerCannotBeNull); Why would you cast null to the type of the object you are checking for null?

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  • How to check if a BOOL is null?

    - by Sheehan Alam
    Is there a way I can check to see if a value is NULL/Nil before assigning it to a BOOL? For example, I have a value in a NSDictionary that can be either TRUE/FALSE/NULL mySTUser.current_user_following = [[results objectForKey:@"current_user_following"]boolValue]; When the value is NULL I get the following error *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSNull boolValue]: unrecognized selector sent to instance I would like to be able to handle the NULL case.

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  • When is `x IS NOT NULL` not the same as `NOT(x IS NULL)`

    - by Mark Hurd
    For what x is The expression x IS NOT NULL is not equal to NOT(x IS NULL), as is the case in 2VL (quote from this answer, which is quoting Fabian Pascal Practical Issues in Database Management - A Reference for the Thinking Practitioner -- near the end of that answer) My guess is when x IS NULL is NULL, but I cannot guess when that would be (i.e. I haven't checked the SQL standard).

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  • Unique ways to use the Null Coalescing operator

    - by Atomiton
    I know the standard way of using the Null coalescing operator in C# is to set default values. string nobody = null; string somebody = "Bob Saget"; string anybody = ""; anybody = nobody ?? "Mr. T"; // returns Mr. T anybody = somebody ?? "Mr. T"; // returns "Bob Saget" But what else can ?? be used for? It doesn't seem as useful as the ternary operator, apart from being more concise and easier to read than: nobody = null; anybody = nobody == null ? "Bob Saget" : nobody; // returns Bob Saget So given that fewer even know about null coalescing operator... Have you used ?? for something else? Is ?? necessary, or should you just use the ternary operator (that most are familiar with)

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  • Deep Null checking, is there a better way?

    - by Mattias Konradsson
    We've all been there, we have some deep property like cake.frosting.berries.loader that we need to check if it's null so there's no exception. The way to do is is to use a short-circuiting if statement if (cake != null && cake.frosting != null && cake.frosting.berries != null) ... This strikes me however as not very elegant, there should perhaps be an easier way to check the entire chain and see if it comes up against a null variable/property. So is it possible using some extension method or would it be a language feature, or is it just a bad idea?

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  • SQL-Join with NULL-columns

    - by tstenner
    I'm having the following tables: Table a +-------+------------------+------+-----+ | Field | Type | Null | Key | +-------+------------------+------+-----+ | bid | int(10) unsigned | YES | | | cid | int(10) unsigned | YES | | +-------+------------------+------+-----+ Table b +-------+------------------+------+ | Field | Type | Null | +-------+------------------+------+ | bid | int(10) unsigned | NO | | cid | int(10) unsigned | NO | | data | int(10) unsigned | NO | +-------+------------------+------+ When I want to select all rows from b where there's a corresponding bid/cid-pair in a, I simply use a natural join SELECT b.* FROM b NATURAL JOIN a; and everything is fine. When a.bid or a.cid is NULL, I want to get every row where the other column matches, e.g. if a.bid is NULL, I want every row where a.cid=b.cid, if both are NULL I want every column from b. My naive solution was this: SELECT DISTINCT b.* FROM b JOIN a ON ( ISNULL(a.bid) OR a.bid=b.bid ) AND (ISNULL(a.cid) OR a.cid=b.cid ) Is there any better way to to this?

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