Does Selecting from XMLNodes Count as 3-Part Naming Convention in SQL Server?-CodePudding

I recently saw a comment from @Larnu highlighting that 3 part naming on columns will soon(ish) be depreciated. There was a link to a useful article on his website which details about this:

https://wp.larnu.uk/3-part-naming-on-columns-will-be-deprecated/

Specifically, it quotes from the depreciated SQL Server features page on docs.microsoft.com (https://docs.microsoft.com/en-us/sql/database-engine/deprecated-database-engine-features-in-sql-server-2016?view=sql-server-ver15):

The following SQL Server Database Engine features are supported in the next version of SQL Server, but will be deprecated in a later version. The specific version of SQL Server has not been determined:

Category Deprecated feature Replacement Feature name Feature ID

Transact-SQL Three-part and four-part column references. Two-part names is the standard-compliant behavior. More than two-part column name 3

Category	Deprecated feature	Replacement Feature	name	Feature ID
Transact-SQL	Three-part and four-part column references.	Two-part names is the standard-compliant behavior.	More than two-part column name	3

My question is does this apply to when using XMLnodes as a column reference? e.g.:

SELECT
    XMLNodes.x.value('@time', 'datetime') as Runtime,
    InnerXMLNode.x.value('@currency', 'varchar(3)') as Currency,
    InnerXMLNode.x.value('@rate', 'Decimal(10,7)') as Rate
from
    @xmlFile.nodes('/Envelope/Cube/Cube') as XMLNodes(x)
    cross apply XMLNodes.x.nodes('Cube') as InnerXMLNode(x)

I can't find anything specifically excluding XMLnodes, but are they technically still columns? If the depreciated feature does include XMLnodes, how do you do this without 3 part naming?

CodePudding user response：

No, it is not. It is just invoking a method on that column.

For example, you can also do

CAST(SomeValue AS xml).value(.....

and clearly that is not three-part naming

The official grammar for SELECT is as follows

<select_list> ::=   
    {   
      *   
      | { table_name | view_name | table_alias }.*   
      | {  
          [ { table_name | view_name | table_alias }. ]  
               { column_name | $IDENTITY | $ROWGUID }   
          | udt_column_name [ { . | :: } { { property_name | field_name }   
            | method_name ( argument [ ,...n] ) } ]  
          | expression  
          [ [ AS ] column_alias ]   
         }  
      | column_alias = expression   
    } [ ,...n ]

and although the grammar is not perfect, you can see that udt_column_name.method_name is not classed as an extra column name.

CodePudding user response：

No, the 3 part naming means when you are naming the object names, for example SchemaName.TableName.ColumnName, that isn't the case in the above.

XMLNodes is the table name, and x the column, however, value is a method of the xml type (basically a function), not an object. So you are using 2 part naming, and then using a method extension of the xml type, just like you are in the FROM for nodes (XMLNodes.x.nodes).