Xml null string value

Value , because null storage is always consistent with the DataColumn's data type. The default value for any System. SqlTypes instance is null. Nulls in System. SqlTypes are type-specific and cannot be represented by a single value, such as DbNull. Use the IsNull property to check for nulls.

Null values can be assigned to a DataColumn as shown in the following code example. You can directly assign null values to SqlTypes variables without triggering an exception.

The code adds one row of known values, one row of null values and then iterates through the DataTable , assigning the values to variables and displaying the output in the console window. Add , DataTable. If an object in the array contains DbNull. Value or its strongly typed counterpart, the same rules as described above are applied. In addition, the following rules apply for an instance of DataRow.

The default value is DbNull. Value for all except the strongly typed null columns where it is the appropriate strongly typed null value. All non-null values, including defaults, are always written out while serializing to XML. The opposite is true for a DataTable : a null value is implicit and the default value is explicit. Rows created using NewRow or similar methods are assigned the DataColumn's default value. The IsNull method returns true for both DbNull.

Value and INullable. When comparing null values, it is important to understand the difference between the way the Equals method evaluates null values in System.

SqlTypes as compared with the way it works with CLR types. Among other things, this name space defines a nil attribute. For your XML document to have a null value in it, you need to declare this namespace in the document and then on the appropriate element s , add the nil attribute.

Most of times the prefix xsi is used for this name space but this is not a requirement. Any other prefix can be used just as well. For better readability I tend to use xsi most the time, and I suggest you all do so too. For example, this code:. If you just use the. Even for the documents with name space mentioned above and the nil attributes in them will get some value returned.

Only if the requested element is missing from the document will you get NULL returned. So how do we retrieve the null value from an element in this document to, for example, insert it into a table? Before I show you the answer, we will have a look at the. The function returns the contents of the element found by following the path and then converts it into the type specified. The content of the element found is always converted into the specified type.

If the contents cannot be converted into this type, some default value is returned. Net; using System. Text; using System. Xml; using Microsoft. SetSqlString 0, nodeRes["Name"]. InnerText ; record. SetSqlString 1, nodeRes["Value"]. InnerText ; pipe. Rene Bottern Rene Bottern 11 2 2 bronze badges.

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