QueryExpression Class

مقالة
11/28/2016

Applies To: Dynamics 365 (online), Dynamics 365 (on-premises), Dynamics CRM 2016, Dynamics CRM Online

Contains a complex query expressed in a hierarchy of expressions.

Namespace: Microsoft.Xrm.Sdk.Query
Assembly: Microsoft.Xrm.Sdk (in Microsoft.Xrm.Sdk.dll)

Inheritance Hierarchy

System.Object
Microsoft.Xrm.Sdk.Query.QueryBase
Microsoft.Xrm.Sdk.Query.QueryExpression

Syntax

[DataContractAttribute(Name = "QueryExpression", Namespace = "https://schemas.microsoft.com/xrm/2011/Contracts")]
public sealed class QueryExpression : QueryBase

<DataContractAttribute(Name := "QueryExpression", Namespace := "https://schemas.microsoft.com/xrm/2011/Contracts")>
Public NotInheritable Class QueryExpression
    Inherits QueryBase

Constructors

	Name	Description
	QueryExpression()	Initializes a new instance of the QueryExpression class.
	QueryExpression(String)	Initializes a new instance of the QueryExpression class setting the entity name.

Properties

	Name	Description
	ColumnSet	Gets or sets the columns to include.
	Criteria	Gets or sets the complex condition and logical filter expressions that filter the results of the query.
	Distinct	Gets or sets whether the results of the query contain duplicate entity instances.
	EntityName	Gets or sets the logical name of the entity.
	ExtensionData	Gets or sets the structure that contains extra data.(Inherited from QueryBase.)
	LinkEntities	Gets a collection of the links between multiple entity types.
	NoLock	Gets or sets a value that indicates that no shared locks are issued against the data that would prohibit other transactions from modifying the data in the records returned from the query.
	Orders	Gets the order in which the entity instances are returned from the query.
	PageInfo	Gets or sets the number of pages and the number of entity instances per page returned from the query.
	TopCount	Gets or sets the number of rows to be returned.

Methods

	Name	Description
	AddLink(String, String, String)	Adds the specified link to the query expression setting the entity name to link to, the attribute name to link from and the attribute name to link to.
	AddLink(String, String, String, JoinOperator)	Adds the specified link to the query expression setting the entity name to link to, the attribute name to link from and the attribute name to link to.
	AddOrder(String, OrderType)	Adds the specified order expression to the query expression.
	Equals(Object)	(Inherited from Object.)
	GetHashCode()	(Inherited from Object.)
	GetType()	(Inherited from Object.)
	ToString()	(Inherited from Object.)

Remarks

QueryExpression provides an object model to construct a query. Queries can also be created using FetchXML, a proprietary XML based query language. You can convert queries between FetchXML and QueryExpression using FetchXmlToQueryExpressionRequest and QueryExpressionToFetchXmlRequest messages. More information: Sample: Convert queries between Fetch and QueryExpression.

Examples


// Build the following SQL query using QueryExpression:
//
//      SELECT contact.fullname, contact.address1_telephone1
//      FROM contact
//          LEFT OUTER JOIN account
//              ON contact.parentcustomerid = account.accountid
//              AND
//              account.name = 'Litware, Inc.'
//      WHERE (contact.address1_stateorprovince = 'WA'
//      AND
//          contact.address1_city in ('Redmond', 'Bellevue', 'Kirkland', 'Seattle')
//      AND 
//          contact.address1_telephone1 like '(206)%'
//          OR
//          contact.address1_telephone1 like '(425)%'
//      AND
//          DATEDIFF(DAY, contact.createdon, GETDATE()) > 0
//      AND
//          DATEDIFF(DAY, contact.createdon, GETDATE()) < 30
//      AND
//          contact.emailaddress1 Not NULL
//             )

QueryExpression query = new QueryExpression()
{
    Distinct = false,
    EntityName = Contact.EntityLogicalName,
    ColumnSet = new ColumnSet("fullname", "address1_telephone1"),
    LinkEntities = 
    {
        new LinkEntity 
        {
            JoinOperator = JoinOperator.LeftOuter,
            LinkFromAttributeName = "parentcustomerid",
            LinkFromEntityName = Contact.EntityLogicalName,
            LinkToAttributeName = "accountid",
            LinkToEntityName = Account.EntityLogicalName,
            LinkCriteria = 
            {
                Conditions = 
                {
                    new ConditionExpression("name", ConditionOperator.Equal, "Litware, Inc.")
                }
            }
        }
    },
    Criteria =
    {
        Filters = 
        {
            new FilterExpression
            {
                FilterOperator = LogicalOperator.And,
                Conditions = 
                {
                    new ConditionExpression("address1_stateorprovince", ConditionOperator.Equal, "WA"),
                    new ConditionExpression("address1_city", ConditionOperator.In, new String[] {"Redmond", "Bellevue" , "Kirkland", "Seattle"}),
                    new ConditionExpression("createdon", ConditionOperator.LastXDays, 30),
                    new ConditionExpression("emailaddress1", ConditionOperator.NotNull)
                },
            },
            new FilterExpression
            {
                FilterOperator = LogicalOperator.Or,
                Conditions =
                {
                    new ConditionExpression("address1_telephone1", ConditionOperator.Like, "(206)%"),
                    new ConditionExpression("address1_telephone1", ConditionOperator.Like, "(425)%")
                }
            }
        }
    }
};

DataCollection<Entity> entityCollection = _service.RetrieveMultiple(query).Entities;

// Display the results.
Console.WriteLine("List all contacts matching specified parameters");
Console.WriteLine("===============================================");
foreach (Contact contact in entityCollection)
{
    Console.WriteLine("Contact ID: {0}", contact.Id);
    Console.WriteLine("Contact Name: {0}", contact.FullName);
    Console.WriteLine("Contact Phone: {0}", contact.Address1_Telephone1);
}
Console.WriteLine("<End of Listing>");
Console.WriteLine();

Thread Safety

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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