Query and Shape Data

• May 11, 2022

Querying a data store allows you to retrieve specific data and store it within a temporary data store for further review and evaluation. In XPO you can obtain query results as:

• Collection of objects (XPCollection, XPCollection<T>, XPCursor, Session.GetObjectsFromQuery, Session.GetObjectsFromSproc, Session.GetObjectsByKeyFromSproc, Session.GetObjectsByKey, Session.GetObjectsByKeyFromQuery, or Session.GetObjectsInTransaction).
• View object (XPDataView or XPView).
• Queryable data source (by executing LINQ queries for XPQuery<T>).

The topics in this section describe how to specify retrieval, sorting, filtering and complex criteria using straightforward object syntax.

The following topics are available:

• LINQ to XPO
• Filtering
• Sorting
• Free Joins
• Stored Procedures
• Direct SQL Queries
• NULL Value Handling Specifics
• Always Encrypted (SQL Server only)
• Delayed Loading
• Optimistic Concurrency
• Custom Collection Types
• Select Data from Multiple Tables

In addition, the following relevant topics are available in the DevExpress Data Library section:

• Criteria Language Syntax
• Criteria Operators
• Simplified Criteria Syntax
• Limitations of CriteriaOperator.Parse
• Custom Aggregate Functions

Note

You can try the functionality described here in the Querying a Data Store section of the XPO Tutorials demo (C:\Users\Public\Documents\DevExpress Demos 23.2\Components\WinForms\Bin\XpoTutorials.exe).