NH-2408 - MsSql2000Dialect.LockHintAppender correct handle table names with explicit catalog name but without schema name in union subclasses

Author: hazzik

src/NHibernate.Test/DialectTest/LockHintAppenderFixture.cs

@@ -80,6 +80,16 @@ public void ShouldHandleExplicitSchemasAndDbNames()
 			Assert.That(result.ToString(), Is.EqualTo(expectedQuery));
 		}
 
+		[Test]
+		public void ShouldHandleExplicitDbNameWithoutSchemaName()
+		{
+			const string expectedQuery =
+				"select Id, Name from (select Id, Name FROM nhibernate..Employee with (updlock, rowlock) union all select Id, Name from Manager with (updlock, rowlock)) as person";
+
+			var result = _appender.AppendLockHint(new SqlString(expectedQuery.Replace(MsSql2000LockHint, string.Empty)));
+			Assert.That(result.ToString(), Is.EqualTo(expectedQuery));
+		}
+
 		[Test]
 		public void ShouldHandleExplicitSchemasAndDbNamesWithSpacesBetweenNameParts()
 		{

src/NHibernate/Dialect/MsSql2000Dialect.cs

@@ -523,7 +523,7 @@ public struct LockHintAppender
 			private const string EscapedNameRegex = @"\[([^\]]|\]\])+\]";
 			private const string NameRegex = "(" + UnescapedNameRegex + "|" + EscapedNameRegex + ")";
 			private const string NameSeparatorRegex = @"\s*\.\s*";
-			private const string FromTableNameRegex = @"from\s+(" + NameRegex + NameSeparatorRegex + "){0,2}" + NameRegex;
+			private const string FromTableNameRegex = @"from\s+(" + NameRegex + "?" + NameSeparatorRegex + "){0,2}" + NameRegex;
 
 			private static readonly Regex FromClauseTableNameRegex = new Regex(FromTableNameRegex, RegexOptions.IgnoreCase | RegexOptions.Multiline);