NH-4022 - Fix dropping sequences in MsSql2012Dialect (nhibernate#647)

Author: hazzik

src/NHibernate.Test/DialectTest/MsSql2012DialectFixture.cs

@@ -155,6 +155,14 @@ SELECT DISTINCT TOP (?) PERCENT WITH TIES @id = id FROM persons WHERE name LIKE
 				EXEC    get_person_summary @id");
 		}
 
+		[Test]
+		public void GetDropSequenceString()
+		{
+			var d = new MsSql2012Dialect();
+
+			Assert.That(d.GetDropSequenceString("[foo].[bar_seq]"), Is.EqualTo("IF EXISTS (SELECT * FROM sys.sequences WHERE object_id = OBJECT_ID(N'[foo].[bar_seq]')) DROP SEQUENCE [foo].[bar_seq]"));
+		}
+
 		private static void VerifyLimitStringForStoredProcedureCalls(string sql)
 		{
 			var d = new MsSql2012Dialect();

src/NHibernate.Test/NHSpecificTest/NH4004/Entity.cs

@@ -0,0 +1,8 @@
+namespace NHibernate.Test.NHSpecificTest.NH4004
+{
+	class Entity
+	{
+		public virtual int Id { get; set; }
+		public virtual string Name { get; set; }
+	}
+}

src/NHibernate.Test/NHSpecificTest/NH4004/Fixture.cs

@@ -0,0 +1,61 @@
+using System.Data;
+using NHibernate.Cfg.MappingSchema;
+using NHibernate.Dialect;
+using NHibernate.Mapping.ByCode;
+using NHibernate.Tool.hbm2ddl;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.NH4004
+{
+	public class Fixture : TestCaseMappingByCode
+	{
+		protected override bool AppliesTo(Dialect.Dialect dialect)
+		{
+			return dialect is MsSql2012Dialect;
+		}
+
+		protected override HbmMapping GetMappings()
+		{
+			var mapper = new ModelMapper();
+			mapper.Class<Entity>(
+				rc =>
+				{
+					rc.Id(
+						x => x.Id,
+						m => m.Generator(
+							Generators.Sequence,
+							gm => gm.Params(
+								new
+								{
+									sequence = "`entity_seq`"
+								}
+							)));
+					rc.Property(x => x.Name);
+				});
+
+			return mapper.CompileMappingForAllExplicitlyAddedEntities();
+		}
+
+		protected override bool CheckDatabaseWasCleaned()
+		{
+			//NO OP
+			return true;
+		}
+
+		[Test]
+		public void SequenceShallBeDropped()
+		{
+			new SchemaExport(cfg).Drop(true, true);
+
+			using (var connection = Sfi.ConnectionProvider.GetConnection())
+			{
+				var command = connection.CreateCommand();
+				command.CommandText = "SELECT COUNT(*) FROM sys.sequences WHERE NAME = 'entity_seq'";
+				command.CommandType = CommandType.Text;
+				var count = (int) command.ExecuteScalar();
+
+				Assert.That(count, Is.EqualTo(0));
+			}
+		}
+	}
+}

src/NHibernate.Test/NHibernate.Test.csproj

@@ -751,6 +751,8 @@
     <Compile Include="NHSpecificTest\EntityWithUserTypeCanHaveLinqGenerators\FooExample.cs" />
     <Compile Include="NHSpecificTest\EntityWithUserTypeCanHaveLinqGenerators\IExample.cs" />
     <Compile Include="Insertordering\NH3931Entities.cs" />
+    <Compile Include="NHSpecificTest\NH4004\Entity.cs" />
+    <Compile Include="NHSpecificTest\NH4004\Fixture.cs" />
     <Compile Include="NHSpecificTest\NH1904\StructFixture.cs" />
     <Compile Include="NHSpecificTest\NH3985\Entity.cs" />
     <Compile Include="NHSpecificTest\NH3985\Fixture.cs" />

src/NHibernate/Dialect/MsSql2012Dialect.cs

@@ -30,7 +30,7 @@ protected override string GetCreateSequenceString(string sequenceName, int initi
 
 		public override string GetDropSequenceString(string sequenceName)
 		{
-			string dropSequence = "IF EXISTS (select * from sys.sequences where name = N'{0}') DROP SEQUENCE {0}";
+			string dropSequence = "IF EXISTS (SELECT * FROM sys.sequences WHERE object_id = OBJECT_ID(N'{0}')) DROP SEQUENCE {0}";
 
 			return string.Format(dropSequence, sequenceName);
 		}