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EntityConnection.Open Method

Establishes a connection to the data source by calling the underlying data provider's Open method.

Namespace:  System.Data.EntityClient
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

public override void Open()

Implements

IDbConnection.Open()

ExceptionCondition
InvalidOperationException

An error occurs when you open the connection, or the name of the underlying data provider is not known.

MetadataException

The inline connection string contains an invalid Metadata keyword value.

To avoid inadvertently putting objects such as System.Data.Common.CommandTrees and ObjectContext out of sync with their metadata, EntityConnection must lock its metadata. No changes to the connection string are allowed after the metadata is locked. The following are two scenarios in which metadata is locked:

  • The EntityConnection instance is constructed through the default constructor, or through the EntityConnection(String) constructor, which accepts a connection string. In either case the connection string might be changed multiple times before the connection is opened. Calling [M:System.Data.EntityClient.EntityConnection.Open()] or [M:System.Data.EntityClient.EntityConnection.GetMetadataWorkspace()] locks the metadata.

  • The EntityConnection instance is constructed through the EntityConnection(MetadataWorkspace, DbConnection) constructor, which that accepts a MetadataWorkspace and a DbConnection. In this case the metadata is locked at construction time. No changes to the connection string are ever allowed.

When metadata is loaded, the EntityConnection verifies that the conceptual model, the storage model, and the mapping file are all present.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5 SP1

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