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  • C# Automatic Properties - Still null after +=?

    - by Sam Schutte
    This seems like a bug to me... I accept that automatic properties, defined as such: public decimal? Total { get; set; } Will be null when they are first accessed. They haven't been initialized, so of course they are null. But, even after setting their value through +=, this decimal? still remains null. So after: Total += 8; Total is still null. How can this be correct? I understand that it's doing a (null + 8), but seems strange that it doesn't pick up that it means it should just be set to 8... Addendums: I made the "null + 8" point in my question - but notice that it works with strings. So, it does null + "hello" just fine, and returns "hello". Therefore, behind the scenes, it is initializing the string to a string object with the value of "hello". The behavior should be the same for the other types, IMO. It might be because a string can accept a null as a value, but still, a null string is not an initialized object, correct? Perhaps it's just because a string isn't a nullable...

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  • (NOT) NULL for NVARCHAR columns

    - by Anders Abel
    Allowing NULL values on a column is normally done to allow the absense of a value to be represented. When using NVARCHAR there is aldready a possibility to have an empty string, without setting the column to NULL. In most cases I cannot see a semantical difference between an NVARCHAR with an empty string and a NULL value for such a column. Setting the column as NOT NULL saves me from having to deal with the possibility of NULL values in the code and it feels better to not have to different representations of "no value" (NULL or an empty string). Will I run into any other problems by setting my NVARCHAR columns to NOT NULL. Performance? Storage size? Anything I've overlooked on the usage of the values in the client code?

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  • SQL Server JOIN with optional NULL values

    - by Paul McLoughlin
    Imagine that we have two tables as follows: Trades ( TradeRef INT NOT NULL, TradeStatus INT NOT NULL, Broker INT NOT NULL, Country VARCHAR(3) NOT NULL ) CTMBroker ( Broker INT NOT NULL, Country VARCHAR(3) NULL ) (These have been simplified for the purpose of this example). Now, if we wish to join these two tables on the Broker column, and if a country exists in the CTMBroker table on the Country, we have the following two choices: SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND ISNULL(B.Country, T.Country) = T.Country or SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND (B.COUNTRY=T.Country OR B.Country IS NULL) These are both logically equivalent, however in this specific circumstance for our database (SQL Server 2008, SP1) two different execution plans are produced for these two queries with the second version significantly outperforming the first version in terms of both time and logical reads. My question really is as follows: as a general rule would (2) be preferred to (1), or does this just happen to be exploiting some particular idiosyncracy of the optimiser in 2008 SP1 (that could therefore change with future versions of SQL Server).

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  • Count The Amount Of Data In An Array Including SOME Null

    - by Josephine
    I'm coding in java and I need to create a function that returns the number of Data objects that are currently in an ArrayList. At the moment I have this: int count = 0; for (int i = 0; i < data.length; i++) { if (data[i] != null) { count ++; } } return count; But the problem is that an array list that includes null data is acceptable, and I have to count their null data towards this counter. How do I include the null data that's in the middle of this array, and not the null data that's not supposed to be counted for? For example, I have some tester code that adds (8),null,null,(23),(25) to the array, and this function should return 5 when the initial array size is 10. Thank you so much

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  • MySql, InnoDB & Null Values

    - by pws5068
    Formerly I was using MyISAM storage engine for MySql and I had defined the combination of three fields to be unique. Now I have switched to InnoDB, which I assume caused this problem, and now NULL != NULL. So for the following table: ID (Auto) | Field_A | Field_B | Field_C I can insert (Field_A,Field_B,Field_C) Values(1,2,NULL) (1,2,NULL) (1,2,NULL) infinitely many times. How can I prevent this behavior?

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  • What is the Null Character literal in TSQL?

    - by David in Dakota
    I am wondering what the literal for a Null character (e.g. '\0') is in TSQL. Note: not a NULL field value, but the null character (see link). I have a column with a mix of typical and a null character. I'm trying to replace the null character with a different value. I would have thought that the following would work but it is unsuccessfull: select REPLACE(field_with_nullchar, char(0), ',') from FOO where BAR = 20

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  • sql error, NULL??

    - by Luke
    So I have a query, can someone let me know if it looks ok content wise? "INSERT INTO ".TBL_MESSAGES." (NULL, 'Your ranking points have changed', 'Due to your recent activity, your ranking points have increased by $r', '2', '$u', '0', '0', '0', '0', NULL, NULL, NULL, NULL, now())"; I can add further information if the query doesnt appear to have a problem? Thanks

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  • SSIS Null Value Questions

    - by Saobi
    I have a table with 5 string columns, all can be NULLs. After I read the data from this table, I want to convert any null values into empty strings. The reason is that I need to compare these columns with columns in another table of the same schema (using conditional split), and null values would cause the comparison to evaluate to NULL. Is there any functionality in SSIS that allows me to convert NULL's to empty strings, or just not having to deal with NULL's at all?

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  • Replace always replacing null values

    - by Mike
    Why does left(FIELD, replace(nullif(charindex('-', FIELD), 0), null, len(FIELD))) always return null? The idea behind the query is that if charindex() returns 0, then convert the results into null, then convert the null into the length of the field. So if '-' does not exist, show the whole string. For some reason it makes every row equal null. Thank you.

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  • Foreign keys and NULL in mySQL

    - by Industrial
    Hi everyone, Can I have a column in my values table (value) referenced as a foreign key to knownValues table, and let it be NULL whenever needed, like in the example: Table: values product type value freevalue 0 1 NULL 100 1 2 NULL 25 3 3 1 NULL Table: types id name prefix 0 length cm 1 weight kg 2 fruit NULL Table: knownValues id Type name 0 2 banana Note: The types in the table values & knownValues are of course referenced into the types table. Thanks!

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  • Timestamp Updating Constantly on /dev/null

    - by motorleague
    I've been working on a problem with a /dev/null file on an AIX system (just for background it looks as though it was inadvertently deleted and recreated as a normal file by somebody), but in trying to determine what caused the problem, I noticed that the timestamp on it seems to update every minute. I've observed this on several AIX servers at my workplace. At present I can't entirely rule out this be something specific to the Application being used at my workplace, so I compared with CentOS and Debian based computers at home last night. The CentOS box, which runs 24 hours, had a mod time on /dev/null of around 4 days ago (during which time it was essentially just being used as a web browser and multimedia player, although it would have had active but essentially unused Apache, MySQL and VMM processes running in the background). The timestamp on /dev/null on the Debian machine, which was a just booted laptop, pretty much reflected the boot time, but I tested redirecting STDIN from, and STDOUT to it, and the modification time was unchanged (I'm not sure 100% sure if directing data to /dev/null constitutes "writing to it" in the way it would a normal file). So my question is essentially, could anybody please offer any advice with regards to what circumstances (permissions changes etc.. aside) might cause the timestamp on /dev/null to update? Thanks very much for any suggestions. Alex.

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  • Unable to relate two MySQL tables (foreign keys)

    - by KPL
    Hello people, Here's my USER table CREATE TABLE IF NOT EXISTS `users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `username` varchar(100) NOT NULL, `expiry` varchar(6) NOT NULL, `contact_id` int(11) NOT NULL, `email` varchar(255) NOT NULL, `password` varchar(100) NOT NULL, `level` int(3) NOT NULL, `active` tinyint(4) NOT NULL DEFAULT '1', PRIMARY KEY (`id`,`email`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; And here's my contact_info table CREATE TABLE IF NOT EXISTS `contact_info` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, `email_address` varchar(255) NOT NULL, `company_name` varchar(255) NOT NULL, `license_number` varchar(255) NOT NULL, `phone` varchar(30) NOT NULL, `fax` varchar(30) NOT NULL, `mobile` varchar(30) NOT NULL, `category` varchar(100) NOT NULL, `country` varchar(20) NOT NULL, `state` varchar(20) NOT NULL, `city` varchar(100) NOT NULL, `postcode` varchar(50) NOT NULL, PRIMARY KEY (`id`,`email_address`), ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; The system uses username to login users.I want to modify it in such a way that it uses email for login. But there's no email_address in users table. I have added foreign key - email in user table(which is email_address in contact_info). How should I query database?

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  • ms-access: missing operator in query expression

    - by every_answer_gets_a_point
    i have this sql statement in access: SELECT * FROM (SELECT [Occurrence Number], [1 0 Preanalytical (Before Testing)], NULL, NULL,NULL FROM [Lab Occurrence Form] WHERE NOT ([1 0 Preanalytical (Before Testing)] IS NULL) UNION SELECT [Occurrence Number], NULL, [2 0 Analytical (Testing Phase)], NULL,NULL FROM [Lab Occurrence Form] WHERE NOT ([2 0 Analytical (Testing Phase)] IS NULL) UNION SELECT [Occurrence Number], NULL, NULL, [3 0 Postanalytical ( After Testing)],NULL FROM [Lab Occurrence Form] WHERE NOT ([3 0 Postanalytical ( After Testing)] IS NULL) UNION SELECT [Occurrence Number], NULL, NULL,NULL [4 0 Other] FROM [Lab Occurrence Form] WHERE NOT ([4 0 Other] IS NULL) ) AS mySubQuery ORDER BY mySubQuery.[Occurrence Number]; everything was fine until i added the last line: SELECT [Occurrence Number], NULL, NULL,NULL [4 0 Other] FROM [Lab Occurrence Form] WHERE NOT ([4 0 Other] IS NULL) i get this error: syntax error (missing operator) in query expression 'NULL [4 0 Other]' anyone have any clues why i am getting this error?

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  • Convert VARCHAR() columns to NVARCHAR()

    - by ChrisD
    We recently underwent an upgrade that required us to change our database columns from varchar to NVarchar, to support unicode characters. Digging through the internet, I found a base script which I modified to handle reserved word table names, and maintain the NULL/NotNull constraint of the columns.   I Ran this script use NWOperationalContent – Your Catalog Name here GO SELECT 'ALTER TABLE ' + isnull(schema_name(syo.id), 'dbo') + '.[' +  syo.name +'] '     + ' ALTER COLUMN [' + syc.name + '] NVARCHAR(' + case syc.length when -1 then 'MAX'         ELSE convert(nvarchar(10),syc.length) end + ') '+         case  syc.isnullable when 1 then ' NULL' ELSE ' NOT NULL' END +';'    FROM sysobjects syo    JOIN syscolumns syc ON      syc.id = syo.id    JOIN systypes syt ON      syt.xtype = syc.xtype    WHERE      syt.name = 'varchar'     and syo.xtype='U'   which produced a series of ALTER statements which I could then execute the tables.  In some cases I had to drop indexes, alter the tables, and re-create the indexes.  There might have been a better way to do that, but manually dropping them got the job done.   use NWMerchandisingContent GO ALTER TABLE Locale Drop Constraint PK_Locale ALTER TABLE Country DROP CONSTRAINT PK_Country GO ALTER TABLE dbo.[Campaign]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[BundleLocalization]  ALTER COLUMN [Locale] NVARCHAR(8)  NOT NULL; ALTER TABLE dbo.[BundleLocalization]  ALTER COLUMN [UnitOfmeasure] NVARCHAR(200)  NULL; ALTER TABLE dbo.[BundleLocalization]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [Locale] NVARCHAR(8)  NOT NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [Imperative] NVARCHAR(MAX)  NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [Instructions] NVARCHAR(MAX)  NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[BundleComponent]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Bundle]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Banner]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Video]  ALTER COLUMN [Link] NVARCHAR(512)  NOT NULL; ALTER TABLE dbo.[Video]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[ProductUsage]  ALTER COLUMN [VideoLink] NVARCHAR(512)  NOT NULL; ALTER TABLE dbo.[ProductUsage]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Thumbnail]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[SkuLocalization]  ALTER COLUMN [Locale] NVARCHAR(8)  NOT NULL; ALTER TABLE dbo.[SkuLocalization]  ALTER COLUMN [UnitOfMeasure] NVARCHAR(150)  NOT NULL; ALTER TABLE dbo.[SkuLocalization]  ALTER COLUMN [SwatchColor] NVARCHAR(50)  NOT NULL; etc.. GO ALTER TABLE Locale ADD CONSTRAINT PK_Locale PRIMARY KEY (LocaleId) ALTER TABLE Country ADD CONSTRAINT PK_Country PRIMARY KEY (CountryId) Note that this alter is non-destructive to the data.   Hope this helps.

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  • Why does this MySQL function return null?

    - by Shore
    Description: the query actually run have 4 results returned,as can be see from below, what I did is just concate the items then return, but unexpectedly,it's null. I think the code is self-explanatory: DELIMITER | DROP FUNCTION IF EXISTS get_idiscussion_ask| CREATE FUNCTION get_idiscussion_ask(iask_id INT UNSIGNED) RETURNS TEXT DETERMINISTIC BEGIN DECLARE done INT DEFAULT 0; DECLARE body varchar(600); DECLARE created DATETIME; DECLARE anonymous TINYINT(1); DECLARE screen_name varchar(64); DECLARE result TEXT; DECLARE cur1 CURSOR FOR SELECT body,created,anonymous,screen_name from idiscussion left join users on idiscussion.uid=users.id where idiscussion.iask_id=iask_id; DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1; SET result = ''; OPEN cur1; REPEAT FETCH cur1 INTO body, created, anonymous, screen_name; SET result = CONCAT(result,'<comment><body><![CDATA[',body,']]></body>','<replier>',if(screen_name is not null and !anonymous,screen_name,''),'</replier>','<created>',created,'</created></comment>'); UNTIL done END REPEAT; CLOSE cur1; RETURN result; END | DELIMITER ; mysql> DELIMITER ; mysql> select get_idiscussion_ask(1); +------------------------+ | get_idiscussion_ask(1) | +------------------------+ | NULL | +------------------------+ 1 row in set (0.01 sec) mysql> SELECT body,created,anonymous,screen_name from idiscussion left join users on idiscussion.uid=users.id where idiscussion.iask_id=1; +------+---------------------+-----------+-------------+ | body | created | anonymous | screen_name | +------+---------------------+-----------+-------------+ | haha | 2009-05-27 04:57:51 | 0 | NULL | | haha | 2009-05-27 04:57:52 | 0 | NULL | | haha | 2009-05-27 04:57:52 | 0 | NULL | | haha | 2009-05-27 04:57:53 | 0 | NULL | +------+---------------------+-----------+-------------+ 4 rows in set (0.00 sec) For those who don't think the code is self-explanatory: Why the function returns NULL?

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  • Varchar columns: Nullable or not.

    - by NYSystemsAnalyst
    The database development standards in our organization state the varchar fields should not allow null values. They should have a default value of an empty string (""). I know this makes querying and concatenation easier, but today, one of my coworkers questioned me about why that standard only existed for varchar types an not other datatypes (int, datetime, etc). I would like to know if others consider this to be a valid, defensible standard, or if varchar should be treated the same as fields of other data types? I believe this standard is valid for the following reason: I believe that an empty string and null values, though technically different, are conceptually the same. An empty, zero length string is a string that does not exist. It has no value. However, a numeric value of 0 is not the same as NULL. For example, if a field called OutstandingBalance has a value of 0, it means there are $0.00 remaining. However, if the same field is NULL, that means the value is unknown. On the other hand, a field called CustomerName with a value of "" is basically the same as a value of NULL because both represent the non-existence of the name. I read somewhere that an analogy for an empty string vs. NULL is that of a blank CD vs. no CD. However, I believe this to be a false analogy because a blank CD still phyically exists and still has physical data space that does not have any meaningful data written to it. Basically, I believe a blank CD is the equivalent of a string of blank spaces (" "), not an empty string. Therefore, I believe a string of blank spaces to be an actual value separate from NULL, but an empty string to be the absense of value conceptually equivalent to NULL. Please let me know if my beliefs regarding variable length strings are valid, or please enlighten me if they are not. I have read several blogs / arguments regarding this subject, but still do not see a true conceptual difference between NULLs and empty strings.

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  • GWT Deserialisation of Persistent Entities (JPA)

    - by slartidan
    Hi everyone, I am currently developing Java/GWT-application which is hosted on a weblogic application server. I am using EJB3.0 with EclipseLink as persistence layer. Sadly my GWT has problems to deserialize persistent entities. It might be helpful for you to know, that I have the EclipseLink-Library in my classpath (including javax.persistence.Entity) am not recieving the persistence objects from a database or persistence-manager - I am creating the objects with standard java code use Eclipse IDE for Java EE Developers for development and deploying and I am compiling my GWT code with the GWT-Plugin (GWT 2.1.0) - my source code is split up in several projects am pretty sure, that the problems occures on client side, since the HTTP response of my server is the same in my working and in my not working example tried to patch javax.persistence.Entity and tried to include several libraries which included javax.persistence.Entity but nothing was helping In my server provides a list of instances of class SerialClass; the interface looks like this: public interface GreetingService extends RemoteService { List<SerialClass> greetServer(); } My onModuleLoad()-Method gets those instances and creates a browser-popup with the information: public void onModuleLoad() { GreetingServiceAsync server = (GreetingServiceAsync) GWT.create(GreetingService.class); server.greetServer(new AsyncCallback<List<SerialClass>>() { public void onFailure(Throwable caught) { } public void onSuccess(List<SerialClass> result) { String resultString = ""; try { for (SerialClass serial : result) { if (serial == null) { resultString += "null "; } else { resultString += ">" + serial.id + "< "; } } } catch (Throwable t) { Window.alert("failed to process"); } Window.alert("success:" + resultString); } }); } My server is looking like this: public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService { public List<SerialClass> greetServer() throws IllegalArgumentException { List<SerialClass> list = new ArrayList<SerialClass>(); for (int i = 0; i < 100; i++) { list.add(new SerialClass()); } return list; } } Case 1 = everything works fine I am using this SerialClass (either without any annotation, or with any annotation other than Entity - for example javax.persistence.PersistenceContext works fine): //@Entity public class SerialClass implements Serializable, IsSerializable { public int id = 4711; } The popup contains (as expected): success:>4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< The data sent over HTTP looks like this: //OK[4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,100,1,["java.util.ArrayList/3821976829","serial.shared.SerialClass/10650133"],0,6] Case 2 = its not working at all I am using this SerialClass: @Entity public class SerialClass implements Serializable, IsSerializable { public int id = 4711; } My popup contains (THIS IS MY PROBLEM): success:>2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null The data sent over HTTP looks like this (exactly the same!): //OK[4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,100,1,["java.util.ArrayList/3821976829","serial.shared.SerialClass/10650133"],0,6] There is no suspicious logging output - neither on server, nor on client. All HTTP-responses have return code 200. My current workaround I am going to try to create transfer objects as a copy of my SerialClass - those transfer objects will look exactly the same, but will not have the @Entity annotation. Alternatively I could try to use the RequestFactory (thanks to @Hilbrand for the hint). I really don't know how to solve that problem and I'm really thankful about any suggestions, hints, tips, links, etc.

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  • null terminating a string

    - by robUK
    Hello, gcc 4.4.4 c89 just wondering what is the standard way to null terminate a string. i.e. However, when I use the NULL I get the warning message. *dest++ = 0; *dest++ = '\0'; *dest++ = NULL; /* Warning: Assignment takes integer from pointer without a cast */ source code I am using: size_t s_strscpy(char *dest, const char *src, const size_t len) { /* Copy the contents from src to dest */ size_t i = 0; for(i = 0; i < len; i++) *dest++ = *src++; /* Null terminate dest */ *dest++ = 0; return i; } Just another quick question. I deliberately commented out the line that null terminates. However, it still correctly printed out the contents of the dest. The caller of this function would send the length of the string by either included the NULL or not. i.e. strlen(src) + 1 or stlen(src). size_t s_strscpy(char *dest, const char *src, const size_t len) { /* Copy the contents from src to dest */ size_t i = 0; /* Don't copy the null terminator */ for(i = 0; i < len - 1; i++) *dest++ = *src++; /* Don't add the Null terminator */ /* *dest++ = 0; */ return i; } Many thanks for any advice,

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  • t-sql help with recursive sort of query

    - by stackoverflowuser
    Hi Based on the following table ID Path --------------------------------------- 1 \\Root 2 \\Root\Node0 3 \\Root\Node0\Node1 4 \\Root\Node0\Node2 5 \\Root\Node3 6 \\Root\Node3\Node4 7 \\Root\Node5 ... N \\Root\Node5\Node6\Node7\Node8\Node9\Node10 so on... There are around 1000 rows in this table. I want to display individual node in seperate columns. Maximum columns to be displayed 5 (i.e. node till 5 level deep). So the output will look as below ID Path Level 0 Level 1 Level 2 Level 3 Level 4 Level 5 ---------------------------------------------------------------------------------------- 1 \\Root Root Null Null Null Null Null 2 \\Root\Node0 Root Node 0 Null Null Null Null 3 \\Root\Node0\Node1 Root Node 0 Node 1 Null Null Null 4 \\Root\Node0\Node2 Root Node 0 Node 2 Null Null Null 5 \\Root\Node3 Root Node 3 Null Null Null Null 6 \\Root\Node3\Node4 Root Node 3 Node 4 Null Null Null 7 \\Root\Node5 Root Node 5 Null Null Null Null ... N (see in above table) Root Node 5 Node 6 Node 7 Node 8 Node 9 The only way i can think of is to open a cursor, loop through each row and perform string split, just fetch the first 5 nodes and then insert into a temp table. Pls. suggest. Thanks

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  • Why null reference exception in SetMolePublicInstance?

    - by OldGrantonian
    I get a "null reference" exception in the following line: MoleRuntime.SetMolePublicInstance(stub, receiverType, objReceiver, name, null); The program builds and compiles correctly. There are no complaints about any of the parameters to the method. Here's the specification of SetMolePublicInstance, from the object browser: SetMolePublicInstance(System.Delegate _stub, System.Type receiverType, object _receiver, string name, params System.Type[] parameterTypes) Here are the parameter values for "Locals": + stub {Method = {System.String <StaticMethodUnitTestWithDeq>b__0()}} System.Func<string> + receiverType {Name = "OrigValue" FullName = "OrigValueP.OrigValue"} System.Type {System.RuntimeType} objReceiver {OrigValueP.OrigValue} object {OrigValueP.OrigValue} name "TestString" string parameterTypes null object[] I know that TestString() takes no parameters and returns string, so as a starter to try to get things working, I specified "null" for the final parameter to SetMolePublicInstance. As already mentioned, this compiles OK. Here's the stack trace: Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.ExtendedReflection.Collections.Indexable.ConvertAllToArray[TInput,TOutput](TInput[] array, Converter`2 converter) at Microsoft.Moles.Framework.Moles.MoleRuntime.SetMole(Delegate _stub, Type receiverType, Object _receiver, String name, MoleBindingFlags flags, Type[] parameterTypes) at Microsoft.Moles.Framework.Moles.MoleRuntime.SetMolePublicInstance(Delegate _stub, Type receiverType, Object _receiver, String name, Type[] parameterTypes) at DeqP.Deq.Replace[T](Func`1 stub, Type receiverType, Object objReceiver, String name) in C:\0VisProjects\DecP_04\DecP\DeqC.cs:line 38 at DeqPTest.DecCTest.StaticMethodUnitTestWithDeq() in C:\0VisProjects\DecP_04\DecPTest\DeqCTest.cs:line 28 at Starter.Start.Main(String[] args) in C:\0VisProjects\DecP_04\Starter\Starter.cs:line 14 Press any key to continue . . . To avoid the null parameter, I changed the final "null" to "parameterTypes" as in the following line: MoleRuntime.SetMolePublicInstance(stub, receiverType, objReceiver, name, parameterTypes); I then tried each of the following (before the line): int[] parameterTypes = null; // if this is null, I don't think the type will matter int[] parameterTypes = new int[0]; object[] parameterTypes = new object[0]; // this would allow for various parameter types All three attempts produce a red squiggly line under the entire line for SetMolePublicInstance Mouseover showed the following message: The best overloaded method match for 'Microsoft.Moles.Framework.Moles.MoleRuntime.SetMolePublicInstance(System.Delegate, System.Type, object, string, params System.Type[])' has some invalid arguments. I'm assuming that the first four arguments are OK, and that the problem is with the params array.

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  • Solving Null Entity Problems with JPA Data Controls in PS1

    - by shay.shmeltzer
    Turns out there is a slight bug that seems to prevent you from doing interactions (update, scroll) with the results of a JPA named query that you dropped on a page using ADF Binding. People are running into this when they are doing the EJB tutorial on OTN for example. The problem is that the way the binding is set up for you automatically doesn't allow you to actually access the iterator set of records to do follow up operations. When I last checked this was solved in the next release of JDeveloper, but in the meantime there is a quick simple way to resolve the issue by changing the refresh condition of the oiterator in your page binding. Here is a little demo that shows the problem and the solution:

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  • C#/.NET Little Wonders: The Nullable static class

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

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  • Are nullable types preferable to magic numbers?

    - by Matt H
    I have been having a little bit of a debate with a coworker lately. We are specifically using C#, but this could apply to any language with nullable types. Say for example you have a value that represents a maximum. However, this maximum value is optional. I argue that a nullable number would be preferable. My coworker favors the use of zero, citing precedent. Granted, things like network sockets have often used zero to represent an unlimited timeout. If I were to write code dealing with sockets today, I would personally use a nullable value, since I feel it would better represent the fact that there is NO timeout. Which representation is better? Both require a condition checking for the value meaning "none", but I believe that a nullable type conveys the intent a little bit better.

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  • Null Or Empty Coalescing

    - by Latest Microsoft Blogs
    In my last blog post, I wrote about the proper way to check for empty enumerations and proposed an IsNullOrEmpty method for collections which sparked a lot of discussion. This post covers a similar issue, but from a different angle. A very long time ago Read More......(read more)

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