dbnull

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How to check for NULL in MySqlDataReader by the column's name?

How can I check for a NULL value in an open MySqlDataReader?开发者_运维百科 The following doesn\'t work; it\'s always hitting the else:[详细]

2023-02-05 07:58 分类：问答
Checking for DBNull throws a StrongTypingException

I am using a dataset to pull data from a DB. One of the fields in a row is NULL. I know this. However, the following vb.net code throws a Str开发者_开发知识库ongTypingException (in the autogenerated g[详细]

2023-02-04 00:24 分类：问答
Operator '??' cannot be applied to operands of type 'string' and 'System.DBNull'

I have the following C# code: sqlCommand.Parameters.AddWithValue(\"@Parameter\", table.Value ?? DBNull.Value);[详细]

2023-01-24 07:12 分类：问答
Handling a DateTime DBNull

I have seen many, many versions of this开发者_Go百科 on SO, but none of them seem to quite work for my needs.[详细]

2023-01-21 03:15 分类：问答
Custom Structure that can be assigned Nothing and/or DBNull?

Please can any one advise me if it is possible to decalre a custom structure that can be assigned Nothing and / or Db开发者_开发问答Null.Values, and also can be instanciated as Nothing?[详细]

2023-01-17 18:40 分类：问答
Returning a DBNull for a bound MaskedTextBox whenever type validation fails?

I have a MaskedTextBox control with the mask \"00/00/0000\", the PromptChar \"_\" and the ValidatingType of DateTime, bound to a DateTime column in a database that can also accept null values.[详细]

2023-01-13 18:58 分类：问答
C#/Oracle10g = null vs DBNull.Value vs String.Empty

I\'m making my first forays into Accessing Oracle from C#. I\'ve discovered that that Oracle doesn\'t like VarChar parameters to have value of null (C#). I would have hoped that there would be some im[详细]

2023-01-12 11:10 分类：问答
DataGridViewComboBox null values

I have a Windows forms DataGridView with a combobox column.The combo box column is bound to a data source that is populated from开发者_运维百科 a Linq to Entities query.I would like users to be able t[详细]

2023-01-11 17:39 分类：问答
DBNull in non-empty cell when reading Excel file through OleDB

I use OleDB to read an Excel file. One of the columns has a \"Common\"开发者_运维百科 format and contains both strings with letters and values consisting of numbers only. String values are retrieved w[详细]

2023-01-06 16:48 分类：问答
DBNull values on an ASP.NET MVC view

I am writing a simple ASP.NET MVC web app. At this point, I am just trying to display a strongly typed DataSet on the automatically generated view. However, some of the values in the DataSe开发者_开发[详细]

2022-12-29 13:38 分类：问答