How do i use xquery

When XQuery is used to query relational data, relational tables are treated as though they are XML documents, and path expressions work the same way as they do for XML.

Because relational tables have a simple structure, path expressions used for tables are usually simple. No standard way exists to access a relational table in XQuery, so each XQuery implementation has its own way of doing this. In DataDirect XQuery, we use fn:collection to access a relational table. For example, the following expression accesses the holdings table. Once you understand the structure of the XML view, you can easily see how path expressions are applied to it.

For example, the following expression finds holdings for the user whose userid is "Minollo". Because relational data is queried as if it were XML, some people think that relational tables are actually extracted from the database, turned into XML documents, and then queried, but this would be very inefficient. This is called an enclosed expression.

For example, the following expression creates a date element whose content is the current date, which is computed when the query is run. Path expressions are frequently used in enclosed expressions. The following expression creates a portfolio element for Minollo, and then extracts Minollo's holdings from the holdings table. FLWOR is pronounced "flower", and is an acronym for the keywords used to introduce each clause for, let, where, order by, and return. FLWOR expressions are frequently used to combine related information.

The possible combinations are generated by using variables in the for clause and using a where clause to filter out combinations that are not useful. This is known as a "join". Consider the following expression:. This expression finds every pair of users elements and holdings elements whose userid child element has the same value, and then builds a holding element that describes the user and his holdings.

A developer can implement any of the above approaches with the XML node to separate the information from the XML column or variable and by using the WHERE provision to put conditions on the same for filter out such certain values of the XML node or element. With the help of Contains, the user can look through any content in the destination XML node with the exist function in the XML data type column.

BusinessEntityID , e. NationalIDNumber , e. OrganizationNode , e. JobTitle ,. Employee e. WHERE e. Author Recent Posts. In the following example, the query is specified against the Instructions column of xml type in ProductModel table in the AdventureWorks database. Note that the XQuery is specified against the Instructions column of xml type. The query method of the xml data type is used to specify the XQuery. The following table lists the related topics that can help in understanding the implementation of XQuery in the Database Engine.

Some of the diagrams provided in this section are taken from that specification. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. Skip to main content. This browser is no longer supported. Cut and paste the following code into the new query to add another book to the books element described in Creating and Inserting a Document into the Database :.

Taking a closer look at this query, we see it uses the xdmp:node-insert-child function to insert the book element as a child of the existing books element. To construct the book element in the same namespace as the books element, we explicitly declare the inserted book element to be in the same namespace as the books element:. Version: MarkLogic 9 MarkLogic Loading TOC First, run the code as follows: Open Query Console in a browser and create a new query. Cut and paste the following code into the XQuery source editor.

Query Console indicated that your query returned the empty sequence.