Query and Shape Data
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 24.