MS CRM: QueryExpression and FetchExpression in Dynamics CRM 2013
QueryExpression and FetchExpression are the classes in CRM SDK to retrieve the data from CRM DB.
Both of them have similarities and differences.
Similarities:
- Can query the CRM data by defining the columns, filter conditions
- Can support Order BY on columns
- Can link with child entities to retrieve the data
- Can group the conditions in filter criteria by using GROUP AND / GROUP OR
- Can query maximum 5000 records in a single run
- Can use Paging cookie to retrieve more than 5000 records.
- QueryExpression and FetchExpression both of them are used in methods that retrieve more than one record (RetrieveMultiple)
Differences:
| Query Expression | Fetch Expression |
| We can’t easily understand the query | Fetch query is very clear and readable compare to Query Expression |
| Aggregate operations are not supported. | Can query the aggregate operation with FetchExpression like Count, sum, AVG, min and Max |
| If we don’t specify the columnset, it will return only one “PrimaryKey” (GUID) column value | If we don’t specify the <attribute> tag in FetchExpression, it will return all columns |
| Query Expression supports intellisense while writing a query. It will make developers job easy. | Fetch Expression doesn’t supports intellisense. Manually we have to check the syntax of Fetch query. [We can download the fetch query from Advanced Find to avoid syntax errors] |
