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问题 In my table 1,00,000 records are there, where 1000 rows and 100 columns are there, some of the records in the table have NULL values, what i want is If the Null valued recorded of entire rows will come to first of my table it can be easy to me to check which row contains and which column contains NULL values If the Value of ROW/COLUM=NULL print all the null valued Rows and columns First Non-Null valued columns print next of the NULL valued rows My Table is like this: Staff_ID First_Name Last

问题 I would like to query for a null field in mongo using python, however it struggles to deal with the words null or false. it either gives me the error that they are undefined in python or it searches for the string null and false in mongo, neither of which I want to happen. collection = pymongo.MongoClient('mongodb://localhost:27017/')['historical'].highjump 1) data = pd.DataFrame(list(collection.find({"min":"null"}))) 2) data = pd.DataFrame(list(collection.find({"min":null}))) 3) data = pd

问题 I have a function that takes in a number of parameters.. it then does a db insert. i have a foreign key on one of the fields (modelID) i want to pass a NULL if no model ID is selected. i tried the following: Dim model As Nullable(Of Integer) If ddlModel.SelectedValue = "Other" Then 'add new model model = cSource.InsertModel(txtModel.Text, ddlManuf.SelectedValue) ElseIf ddlModel.SelectedValue = "0" Then model = Nothing Else model = ddlModel.SelectedValue End If but now i get an error saying:

问题 I have a data structure which uses composite ids (Which I dont wish to change to single) Everything loads fine except for many-to-one joins which if the join is empty, instead of mapping the property to null, maps it to an empty proxy object. I have written an ugly work around( see bleow). Any solutions to this? private Node _Parent; public Node Parent { get { return this._Parent; } set { this._Parent = Proxy.Check<Node>(value); } } internal static class Proxy { public static T Check<T>(T obj

问题 I have a function something like: MyClass1 mc1, mc0; //Single Object MyClass2 mc2; //vector of MyClass1 mc1.Init(1); mc2.Add(mc1); mc1 = mc0; mc1.Init(2); mc2.Add(mc1); mc1 = mc0; //so on...... I actually want to set mc1 = null before at the beginning of the step but cannot do that in C++. So I kept a never-initialized mc0 to do that. Don't think this is an elegant solution. My background was mainly about C# and ASP.NET which is managed.(I think the unmanaged attribute of C++ is the reason

问题 HI i am in desperate need for help here, I am making a web request and getting a json string with Response.ContentLenth=2246 but when i parse it in a string it gives only few 100 characters, i traked it down that it is only getting values less than 964. strings length is still 2246 but remaining values are just (\0) null characters. Its also giving an error Unterminated string passed in. (2246): at following line FacebookFeed feed = sr.Deserialize<FacebookFeed>(data); It works fine if the

问题 i have a BooundColumn in my telerik RadGrid like below : <telerik:GridBoundColumn DataField="Status" FilterControlAltText="Filter Status column" HeaderText="Status" SortExpression="Status" UniqueName="Status" FilterImageToolTip="Filter"> <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" /> <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" /> </telerik:GridBoundColumn> Status Column in my sql server 2008 database can accept null values and RadGrid shows them with an empty

问题 I am a total beginner at VB.NET so you may need to bear with me but I need to edit this code behind so that a null value is passed to my database for the 'imageurl' field. The front end is a web form where a user can enter details of a book, with the option of uploading a book cover. I want to change my code so that if the file upload dialog does not fulfil hasFile, the GUID string generated in the database will be a NULL value (this is so I can have a 'no image available' image using the

问题 This using json.net (C#). Not sure why JToken is not null. var obj = new JObject(); obj["field1"] = null; var token = obj["field1"]; Console.WriteLine(token == null); // false Console.WriteLine(token.ToString() == ""); // true Console.WriteLine(token.Type == JTokenType.Null); // true 回答1: This is by design. Json.NET never allows an actual null JToken value to appear in a JToken hierarchy, either as an JArray member or a JProperty value. Instead, if applications code attempts to set or add a

问题 I'm trying to validate my document for HTML5 using the W3C validator at http://validator.w3.org/check. When I run the code below using "direct input" I get error messages like Element head is missing a required instance of child element title and Stray start tag html . This baffles me, because the <html> tag is right there. Why can't the validator see it? <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <meta name="description" content="some content"> <title>page title</title> </head>