diff --git a/src/Orchard/Data/Migration/Interpreters/DefaultDataMigrationInterpreter.cs b/src/Orchard/Data/Migration/Interpreters/DefaultDataMigrationInterpreter.cs
index d6dfacbe7..e3f5d958c 100644
--- a/src/Orchard/Data/Migration/Interpreters/DefaultDataMigrationInterpreter.cs
+++ b/src/Orchard/Data/Migration/Interpreters/DefaultDataMigrationInterpreter.cs
@@ -125,41 +125,54 @@ namespace Orchard.Data.Migration.Interpreters {
                 return;
             }
 
-            // drop columns
+            // Drop columns.
             foreach (var dropColumn in command.TableCommands.OfType<DropColumnCommand>()) {
                 var builder = new StringBuilder();
                 Visit(builder, dropColumn);
                 RunPendingStatements();
             }
 
-            // add columns
+            // Add columns.
             foreach (var addColumn in command.TableCommands.OfType<AddColumnCommand>()) {
                 var builder = new StringBuilder();
                 Visit(builder, addColumn);
                 RunPendingStatements();
             }
 
-            // alter columns
+            // Alter columns.
             foreach (var alterColumn in command.TableCommands.OfType<AlterColumnCommand>()) {
                 var builder = new StringBuilder();
                 Visit(builder, alterColumn);
                 RunPendingStatements();
             }
 
-            // add index
+            // Add index.
             foreach (var addIndex in command.TableCommands.OfType<AddIndexCommand>()) {
                 var builder = new StringBuilder();
                 Visit(builder, addIndex);
                 RunPendingStatements();
             }
 
-            // drop index
+            // Drop index.
             foreach (var dropIndex in command.TableCommands.OfType<DropIndexCommand>()) {
                 var builder = new StringBuilder();
                 Visit(builder, dropIndex);
                 RunPendingStatements();
             }
 
+            // Add unique constraint.
+            foreach (var addUniqueConstraint in command.TableCommands.OfType<AddUniqueConstraintCommand>()) {
+                var builder = new StringBuilder();
+                Visit(builder, addUniqueConstraint);
+                RunPendingStatements();
+            }
+
+            // Drop unique constraint.
+            foreach (var dropUniqueConstraint in command.TableCommands.OfType<DropUniqueConstraintCommand>()) {
+                var builder = new StringBuilder();
+                Visit(builder, dropUniqueConstraint);
+                RunPendingStatements();
+            }
         }
 
         public void Visit(StringBuilder builder, AddColumnCommand command) {
@@ -210,7 +223,6 @@ namespace Orchard.Data.Migration.Interpreters {
             _sqlStatements.Add(builder.ToString());
         }
 
-
         public void Visit(StringBuilder builder, AddIndexCommand command) {
             if (ExecuteCustomInterpreter(command)) {
                 return;
@@ -235,6 +247,31 @@ namespace Orchard.Data.Migration.Interpreters {
             _sqlStatements.Add(builder.ToString());
         }
 
+        public void Visit(StringBuilder builder, AddUniqueConstraintCommand command) {
+            if (ExecuteCustomInterpreter(command)) {
+                return;
+            }
+
+            builder.AppendFormat("alter table {0} add constraint {1} unique ({2})",
+                _dialectLazy.Value.QuoteForTableName(PrefixTableName(command.TableName)),
+                _dialectLazy.Value.QuoteForColumnName(PrefixTableName(command.ConstraintName)),
+                String.Join(", ", command.ColumnNames));
+
+            _sqlStatements.Add(builder.ToString());
+        }
+
+        public void Visit(StringBuilder builder, DropUniqueConstraintCommand command) {
+            if (ExecuteCustomInterpreter(command)) {
+                return;
+            }
+
+            builder.AppendFormat("alter table {0} drop constraint {1}",
+                _dialectLazy.Value.QuoteForTableName(PrefixTableName(command.TableName)),
+                _dialectLazy.Value.QuoteForColumnName(PrefixTableName(command.ConstraintName)));
+
+            _sqlStatements.Add(builder.ToString());
+        }
+
         public override void Visit(SqlStatementCommand command) {
             if (command.Providers.Count != 0 && !command.Providers.Contains(_shellSettings.DataProvider)) {
                 return;
diff --git a/src/Orchard/Data/Migration/Schema/AddUniqueConstraintCommand.cs b/src/Orchard/Data/Migration/Schema/AddUniqueConstraintCommand.cs
new file mode 100644
index 000000000..138a24294
--- /dev/null
+++ b/src/Orchard/Data/Migration/Schema/AddUniqueConstraintCommand.cs
@@ -0,0 +1,13 @@
+namespace Orchard.Data.Migration.Schema {
+    public class AddUniqueConstraintCommand : TableCommand {
+        public string ConstraintName { get; set; }
+
+        public AddUniqueConstraintCommand(string tableName, string constraintName, params string[] columnNames)
+            : base(tableName) {
+            ColumnNames = columnNames;
+            ConstraintName = constraintName;
+        }
+
+        public string[] ColumnNames { get; private set; }
+    }
+}
diff --git a/src/Orchard/Data/Migration/Schema/AlterTableCommand.cs b/src/Orchard/Data/Migration/Schema/AlterTableCommand.cs
index 0b8d370e9..a843a0831 100644
--- a/src/Orchard/Data/Migration/Schema/AlterTableCommand.cs
+++ b/src/Orchard/Data/Migration/Schema/AlterTableCommand.cs
@@ -47,5 +47,15 @@ namespace Orchard.Data.Migration.Schema {
             var command = new DropIndexCommand(Name, indexName);
             TableCommands.Add(command);
         }
+
+        public void CreateUniqueConstraint(string constraintName, params string[] columnNames) {
+            var command = new AddUniqueConstraintCommand(Name, constraintName, columnNames);
+            TableCommands.Add(command);
+        }
+
+        public void DropUniqueConstraint(string constraintName) {
+            var command = new DropUniqueConstraintCommand(Name, constraintName);
+            TableCommands.Add(command);
+        }
     }
 }
diff --git a/src/Orchard/Data/Migration/Schema/DropUniqueConstraintCommand.cs b/src/Orchard/Data/Migration/Schema/DropUniqueConstraintCommand.cs
new file mode 100644
index 000000000..af8b5c3f3
--- /dev/null
+++ b/src/Orchard/Data/Migration/Schema/DropUniqueConstraintCommand.cs
@@ -0,0 +1,10 @@
+namespace Orchard.Data.Migration.Schema {
+    public class DropUniqueConstraintCommand : TableCommand {
+        public string ConstraintName { get; set; }
+
+        public DropUniqueConstraintCommand(string tableName, string constraintName)
+            : base(tableName) {
+            ConstraintName = constraintName;
+        }
+    }
+}
diff --git a/src/Orchard/Orchard.Framework.csproj b/src/Orchard/Orchard.Framework.csproj
index 216323343..8bec83054 100644
--- a/src/Orchard/Orchard.Framework.csproj
+++ b/src/Orchard/Orchard.Framework.csproj
@@ -149,6 +149,8 @@
     <Reference Include="System.Xml.Linq" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Data\Migration\Schema\AddUniqueConstraintCommand.cs" />
+    <Compile Include="Data\Migration\Schema\DropUniqueConstraintCommand.cs" />
     <Compile Include="Environment\Extensions\Helpers\ExtensionManagerExtensions.cs" />
     <Compile Include="Environment\Extensions\Models\LifecycleStatus.cs" />
     <Compile Include="Mvc\Updater.cs" />