diff --git a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLOperatorExpressionParser.cs b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLOperationExpressionParser.cs
similarity index 86%
rename from TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLOperatorExpressionParser.cs
rename to TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLOperationExpressionParser.cs
index e7c2bad..c50051a 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLOperatorExpressionParser.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLOperationExpressionParser.cs
@@ -8,13 +8,13 @@
 
 namespace TSQL.Expressions.Parsers
 {
-	internal class TSQLOperatorExpressionParser
+	internal class TSQLOperationExpressionParser
 	{
-		public TSQLOperatorExpression Parse(
+		public TSQLOperationExpression Parse(
 			ITSQLTokenizer tokenizer,
 			TSQLExpression leftSide)
 		{
-			TSQLOperatorExpression opExpression = new TSQLOperatorExpression();
+			TSQLOperationExpression opExpression = new TSQLOperationExpression();
 
 			opExpression.LeftSide = leftSide;
 			opExpression.Operator = tokenizer.Current.AsOperator;
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLSelectExpressionParser.cs b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLSelectExpressionParser.cs
index 8901e88..5152d1a 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLSelectExpressionParser.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLSelectExpressionParser.cs
@@ -51,7 +51,7 @@ public TSQLExpression Parse(ITSQLTokenizer tokenizer)
 				}
 				else
 				{
-					return new TSQLOperatorExpressionParser().Parse(
+					return new TSQLOperationExpressionParser().Parse(
 						tokenizer,
 						expression);
 				}
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLValueExpressionParser.cs b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLValueExpressionParser.cs
index 2be6776..92de3d9 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLValueExpressionParser.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLValueExpressionParser.cs
@@ -22,7 +22,7 @@ public TSQLExpression Parse(ITSQLTokenizer tokenizer)
 				tokenizer.Current.Type.In(
 					TSQLTokenType.Operator))
 			{
-				return new TSQLOperatorExpressionParser().Parse(
+				return new TSQLOperationExpressionParser().Parse(
 					tokenizer,
 					expression);
 			}
@@ -125,6 +125,39 @@ public TSQLExpression ParseNext(
 					#endregion
 				}
 			}
+			else if (
+					tokenizer.Current.IsKeyword(TSQLKeywords.DISTINCT) ||
+					tokenizer.Current.IsKeyword(TSQLKeywords.ALL))
+			{
+				#region parse rest of expression contained inside parenthesis
+
+				TSQLDuplicateSpecificationExpression distinct = new TSQLDuplicateSpecificationExpression();
+
+				distinct.Tokens.Add(tokenizer.Current);
+
+				if (tokenizer.Current.IsKeyword(TSQLKeywords.ALL))
+				{
+					distinct.DuplicateSpecificationType = TSQLDuplicateSpecificationExpression.TSQLDuplicateSpecificationType.All;
+				}
+				else
+				{
+					distinct.DuplicateSpecificationType = TSQLDuplicateSpecificationExpression.TSQLDuplicateSpecificationType.Distinct;
+				}
+
+				TSQLTokenParserHelper.ReadThroughAnyCommentsOrWhitespace(
+					tokenizer,
+					distinct.Tokens);
+
+				distinct.InnerExpression =
+					new TSQLValueExpressionParser().Parse(
+						tokenizer);
+
+				distinct.Tokens.AddRange(distinct.InnerExpression.Tokens);
+
+				return distinct;
+
+				#endregion
+			}
 			else if (tokenizer.Current.Type.In(
 				TSQLTokenType.Variable,
 				TSQLTokenType.SystemVariable))
@@ -158,6 +191,18 @@ public TSQLExpression ParseNext(
 
 				return constant;
 			}
+			else if (tokenizer.Current.IsKeyword(TSQLKeywords.NULL))
+			{
+				TSQLNullExpression nullExp = new TSQLNullExpression();
+
+				nullExp.Tokens.Add(tokenizer.Current);
+
+				TSQLTokenParserHelper.ReadThroughAnyCommentsOrWhitespace(
+					tokenizer,
+					nullExp.Tokens);
+
+				return nullExp;
+			}
 			else if (tokenizer.Current.IsKeyword(TSQLKeywords.CASE))
 			{
 				return new TSQLCaseExpressionParser().Parse(tokenizer);
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLVariableAssignmentExpressionParser.cs b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLVariableAssignmentExpressionParser.cs
index d1d03d4..8bd3e40 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLVariableAssignmentExpressionParser.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/Parsers/TSQLVariableAssignmentExpressionParser.cs
@@ -44,7 +44,7 @@ public TSQLVariableAssignmentExpression Parse(
 				tokenizer.Current.Type.In(
 					TSQLTokenType.Operator))
 			{
-				rightSide = new TSQLOperatorExpressionParser().Parse(
+				rightSide = new TSQLOperationExpressionParser().Parse(
 					tokenizer,
 					rightSide);
 			}
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/TSQLDuplicateSpecificationExpression.cs b/TSQL_Parser/TSQL_Parser/Expressions/TSQLDuplicateSpecificationExpression.cs
new file mode 100644
index 0000000..46577c2
--- /dev/null
+++ b/TSQL_Parser/TSQL_Parser/Expressions/TSQLDuplicateSpecificationExpression.cs
@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using TSQL.Tokens;
+
+namespace TSQL.Expressions
+{
+	public class TSQLDuplicateSpecificationExpression : TSQLExpression
+	{
+		public override TSQLExpressionType Type
+		{
+			get
+			{
+				return TSQLExpressionType.DuplicateSpecification;
+			}
+		}
+
+		public TSQLDuplicateSpecificationType DuplicateSpecificationType { get; internal set; }
+
+		public TSQLExpression InnerExpression { get; internal set; }
+
+		public enum TSQLDuplicateSpecificationType
+		{
+			Distinct,
+			All
+		}
+	}
+}
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpression.cs b/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpression.cs
index 0b65bce..f9fba39 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpression.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpression.cs
@@ -72,11 +72,11 @@ public TSQLMulticolumnExpression AsMulticolumn
 			}
 		}
 
-		public TSQLOperatorExpression AsOperator
+		public TSQLOperationExpression AsOperation
 		{
 			get
 			{
-				return this as TSQLOperatorExpression;
+				return this as TSQLOperationExpression;
 			}
 		}
 
@@ -119,5 +119,21 @@ public TSQLValueAsTypeExpression AsValueAsType
 				return this as TSQLValueAsTypeExpression;
 			}
 		}
+
+		public TSQLNullExpression AsNull
+		{
+			get
+			{
+				return this as TSQLNullExpression;
+			}
+		}
+
+		public TSQLDuplicateSpecificationExpression AsDuplicateSpecification
+		{
+			get
+			{
+				return this as TSQLDuplicateSpecificationExpression;
+			}
+		}
 	}
 }
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpressionType.cs b/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpressionType.cs
index 1a1b2c8..7195219 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpressionType.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/TSQLExpressionType.cs
@@ -29,7 +29,7 @@ public enum TSQLExpressionType
 		/// </summary>
 		Multicolumn,
 
-		Operator,
+		Operation,
 
 		/// <summary>
 		///		i.e. an expression surrounded by parenthesis, but not containing a subquery
@@ -54,6 +54,16 @@ public enum TSQLExpressionType
 		/// <summary>
 		///		e.g. 123.45 AS INT (only used as an argument to CAST function)
 		/// </summary>
-		ValueAsType
+		ValueAsType,
+
+		/// <summary>
+		///		e.g. NULL
+		/// </summary>
+		Null,
+
+		/// <summary>
+		///		e.g. DISTINCT or ALL
+		/// </summary>
+		DuplicateSpecification
 	}
 }
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/TSQLNullExpression.cs b/TSQL_Parser/TSQL_Parser/Expressions/TSQLNullExpression.cs
new file mode 100644
index 0000000..c44d66f
--- /dev/null
+++ b/TSQL_Parser/TSQL_Parser/Expressions/TSQLNullExpression.cs
@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using TSQL.Tokens;
+
+namespace TSQL.Expressions
+{
+	public class TSQLNullExpression : TSQLExpression
+	{
+		public override TSQLExpressionType Type
+		{
+			get
+			{
+				return TSQLExpressionType.Null;
+			}
+		}
+	}
+}
diff --git a/TSQL_Parser/TSQL_Parser/Expressions/TSQLOperatorExpression.cs b/TSQL_Parser/TSQL_Parser/Expressions/TSQLOperationExpression.cs
similarity index 81%
rename from TSQL_Parser/TSQL_Parser/Expressions/TSQLOperatorExpression.cs
rename to TSQL_Parser/TSQL_Parser/Expressions/TSQLOperationExpression.cs
index 40dc815..d19322b 100644
--- a/TSQL_Parser/TSQL_Parser/Expressions/TSQLOperatorExpression.cs
+++ b/TSQL_Parser/TSQL_Parser/Expressions/TSQLOperationExpression.cs
@@ -8,13 +8,13 @@
 
 namespace TSQL.Expressions
 {
-	public class TSQLOperatorExpression : TSQLExpression
+	public class TSQLOperationExpression : TSQLExpression
 	{
 		public override TSQLExpressionType Type
 		{
 			get
 			{
-				return TSQLExpressionType.Operator;
+				return TSQLExpressionType.Operation;
 			}
 		}
 
diff --git a/TSQL_Parser/TSQL_Parser/Properties/AssemblyInfo.cs b/TSQL_Parser/TSQL_Parser/Properties/AssemblyInfo.cs
index 48c43df..453991e 100644
--- a/TSQL_Parser/TSQL_Parser/Properties/AssemblyInfo.cs
+++ b/TSQL_Parser/TSQL_Parser/Properties/AssemblyInfo.cs
@@ -32,7 +32,7 @@
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("2.3.0.0")]
-[assembly: AssemblyFileVersion("2.3.0.0")]
+[assembly: AssemblyVersion("2.4.0.0")]
+[assembly: AssemblyFileVersion("2.4.0.0")]
 
 [assembly: InternalsVisibleTo("Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100793625650b945744f8a2c57bc75da89cd4d2c551636aa180c3020b7a15b815c10e983e83c312eb02f131c6fcf18aaffd6c8d9af6c4353c91ca0e9206b0fb8fb7805fc07b510a47ff40705ae56977ae8893e2d247d166aa400926582840e8a5602df055762bc3479dd14c9621a77946b6e6b0a00a77204c78fb52c65121bd75ba")]
\ No newline at end of file
diff --git a/TSQL_Parser/TSQL_Parser/Push.bat b/TSQL_Parser/TSQL_Parser/Push.bat
index 0a3c997..ccdbae9 100644
--- a/TSQL_Parser/TSQL_Parser/Push.bat
+++ b/TSQL_Parser/TSQL_Parser/Push.bat
@@ -1,4 +1,4 @@
 nuget SetApiKey %NUGET_KEY%
-nuget push TSQL.Parser.2.3.0.snupkg -Source https://api.nuget.org/v3/index.json
-nuget push TSQL.Parser.2.3.0.nupkg -Source https://api.nuget.org/v3/index.json
+nuget push TSQL.Parser.2.4.0.snupkg -Source https://api.nuget.org/v3/index.json
+nuget push TSQL.Parser.2.4.0.nupkg -Source https://api.nuget.org/v3/index.json
 pause
\ No newline at end of file
diff --git a/TSQL_Parser/TSQL_Parser/TSQL_Parser.csproj b/TSQL_Parser/TSQL_Parser/TSQL_Parser.csproj
index 4227243..be17de6 100644
--- a/TSQL_Parser/TSQL_Parser/TSQL_Parser.csproj
+++ b/TSQL_Parser/TSQL_Parser/TSQL_Parser.csproj
@@ -118,7 +118,7 @@
     <Compile Include="Expressions\Parsers\TSQLValueExpressionParser.cs" />
     <Compile Include="Expressions\Parsers\TSQLSelectExpressionParser.cs" />
     <Compile Include="Elements\Parsers\TSQLValuesParser.cs" />
-    <Compile Include="Expressions\Parsers\TSQLOperatorExpressionParser.cs" />
+    <Compile Include="Expressions\Parsers\TSQLOperationExpressionParser.cs" />
     <Compile Include="Expressions\TSQLArgumentList.cs" />
     <Compile Include="Expressions\TSQLArgumentList.IEnumerable.cs">
       <DependentUpon>TSQLArgumentList.cs</DependentUpon>
@@ -126,10 +126,11 @@
     <Compile Include="Expressions\TSQLColumnExpression.cs" />
     <Compile Include="Elements\TSQLDefaultValues.cs" />
     <Compile Include="Expressions\TSQLConstantExpression.cs" />
+    <Compile Include="Expressions\TSQLDuplicateSpecificationExpression.cs" />
     <Compile Include="Expressions\TSQLValueAsTypeExpression.cs" />
     <Compile Include="Expressions\TSQLVariableAssignmentExpression.cs" />
     <Compile Include="Expressions\TSQLLogicalExpression.cs" />
-    <Compile Include="Expressions\TSQLOperatorExpression.cs" />
+    <Compile Include="Expressions\TSQLOperationExpression.cs" />
     <Compile Include="Expressions\TSQLExpressionType.cs" />
     <Compile Include="Expressions\TSQLFunctionExpression.cs" />
     <Compile Include="Expressions\TSQLGroupedExpression.cs" />
@@ -140,6 +141,7 @@
     <Compile Include="Expressions\TSQLCaseExpression.cs" />
     <Compile Include="Expressions\Parsers\TSQLCaseExpressionParser.cs" />
     <Compile Include="Expressions\TSQLExpression.cs" />
+    <Compile Include="Expressions\TSQLNullExpression.cs" />
     <Compile Include="Expressions\TSQLVariableExpression.cs" />
     <Compile Include="IO\BufferedTextReader.cs" />
     <Compile Include="IO\BufferedTextReader.IDisposable.cs">
diff --git a/TSQL_Parser/TSQL_Parser/TSQL_Parser.nuspec b/TSQL_Parser/TSQL_Parser/TSQL_Parser.nuspec
index 7e132aa..7d08247 100644
--- a/TSQL_Parser/TSQL_Parser/TSQL_Parser.nuspec
+++ b/TSQL_Parser/TSQL_Parser/TSQL_Parser.nuspec
@@ -2,7 +2,7 @@
 <package>
 	<metadata>
 		<id>TSQL.Parser</id>
-		<version>2.3.0</version>
+		<version>2.4.0</version>
 		<title>TSQL.Parser</title>
 		<authors>Bruce Dunwiddie</authors>
 		<owners>shriop</owners>
@@ -10,7 +10,7 @@
 		<projectUrl>https://github.com/bruce-dunwiddie/tsql-parser</projectUrl>
 		<requireLicenseAcceptance>false</requireLicenseAcceptance>
 		<description>Library for Parsing SQL Server T-SQL Scripts</description>
-		<releaseNotes>Fixed handling of asterisks within SELECT, as both multiplication and multicolumn expression.</releaseNotes>
+		<releaseNotes>Fixed handling of NULL in SELECT, and DISTINCT in COUNT().</releaseNotes>
 		<copyright>Copyright © 2022</copyright>
 		<tags>sql parser sql-server tsql</tags>
 	</metadata>
diff --git a/TSQL_Parser/TSQL_Parser/TSQL_Parser_NetStandard.csproj b/TSQL_Parser/TSQL_Parser/TSQL_Parser_NetStandard.csproj
index d1328e9..2c99c6e 100644
--- a/TSQL_Parser/TSQL_Parser/TSQL_Parser_NetStandard.csproj
+++ b/TSQL_Parser/TSQL_Parser/TSQL_Parser_NetStandard.csproj
@@ -4,9 +4,9 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyName>TSQL_Parser</AssemblyName>
     <RootNamespace>TSQL_Parser</RootNamespace>
-    <Version>2.3.0.0</Version>
-    <AssemblyVersion>2.3.0.0</AssemblyVersion>
-    <FileVersion>2.3.0.0</FileVersion>
+    <Version>2.4.0.0</Version>
+    <AssemblyVersion>2.4.0.0</AssemblyVersion>
+    <FileVersion>2.4.0.0</FileVersion>
     <Description>Library for Parsing SQL Server TSQL Scripts</Description>
     <Copyright>Copyright © 2022</Copyright>
     <Company />
diff --git a/TSQL_Parser/Tests/Clauses/SelectClauseTests.cs b/TSQL_Parser/Tests/Clauses/SelectClauseTests.cs
index 256622f..f99ec5e 100644
--- a/TSQL_Parser/Tests/Clauses/SelectClauseTests.cs
+++ b/TSQL_Parser/Tests/Clauses/SelectClauseTests.cs
@@ -59,18 +59,18 @@ public void SelectClause_Comments()
 
 				Assert.AreEqual(1, select.Columns.Count);
 				Assert.IsNull(select.Columns[0].ColumnAlias);
-				Assert.AreEqual(TSQLExpressionType.Operator, select.Columns[0].Expression.Type);
+				Assert.AreEqual(TSQLExpressionType.Operation, select.Columns[0].Expression.Type);
 
-				TSQLOperatorExpression operatorExpression = select.Columns[0].Expression.AsOperator;
-				Assert.AreEqual("/", operatorExpression.Operator.Text);
-				Assert.AreEqual(TSQLExpressionType.Column, operatorExpression.LeftSide.Type);
+				TSQLOperationExpression operationExpression = select.Columns[0].Expression.AsOperation;
+				Assert.AreEqual("/", operationExpression.Operator.Text);
+				Assert.AreEqual(TSQLExpressionType.Column, operationExpression.LeftSide.Type);
 
-				TSQLColumnExpression leftSide = operatorExpression.LeftSide.AsColumn;
+				TSQLColumnExpression leftSide = operationExpression.LeftSide.AsColumn;
 				Assert.AreEqual("oh", leftSide.TableReference.Single().AsIdentifier.Name);
 				Assert.AreEqual("TaxAmt", leftSide.Column.Name);
-				Assert.AreEqual(TSQLExpressionType.Column, operatorExpression.RightSide.Type);
+				Assert.AreEqual(TSQLExpressionType.Column, operationExpression.RightSide.Type);
 
-				TSQLColumnExpression rightSide = operatorExpression.RightSide.AsColumn;
+				TSQLColumnExpression rightSide = operationExpression.RightSide.AsColumn;
 				Assert.AreEqual("oh", rightSide.TableReference.Single().AsIdentifier.Name);
 				Assert.AreEqual("SubTotal", rightSide.Column.Name);
 				Assert.AreEqual(" tax percent ", select.Columns.Last().Tokens.Last().AsMultilineComment.Comment);
@@ -327,9 +327,9 @@ public void SelectClause_UnaryOperator()
 				TSQLSelectColumn column = select.Columns[0];
 
 				Assert.IsNull(column.ColumnAlias);
-				Assert.AreEqual(TSQLExpressionType.Operator, column.Expression.Type);
+				Assert.AreEqual(TSQLExpressionType.Operation, column.Expression.Type);
 
-				TSQLOperatorExpression tsqlOperator = column.Expression.AsOperator;
+				TSQLOperationExpression tsqlOperator = column.Expression.AsOperation;
 
 				Assert.AreEqual("+", tsqlOperator.Operator.Text);
 				Assert.IsNull(tsqlOperator.LeftSide);
diff --git a/TSQL_Parser/Tests/Expressions/OperatorExpressionTests.cs b/TSQL_Parser/Tests/Expressions/OperationExpressionTests.cs
similarity index 89%
rename from TSQL_Parser/Tests/Expressions/OperatorExpressionTests.cs
rename to TSQL_Parser/Tests/Expressions/OperationExpressionTests.cs
index 77020db..414cda9 100644
--- a/TSQL_Parser/Tests/Expressions/OperatorExpressionTests.cs
+++ b/TSQL_Parser/Tests/Expressions/OperationExpressionTests.cs
@@ -16,10 +16,10 @@
 namespace Tests.Expressions
 {
 	[TestFixture(Category = "Expression Parsing")]
-	public class OperatorExpressionTests
+	public class OperationExpressionTests
 	{
 		[Test]
-		public void OperatorExpression_Simple()
+		public void OperationExpression_Simple()
 		{
 			TSQLTokenizer tokenizer = new TSQLTokenizer(
 				"+ 2 - 3")
@@ -38,7 +38,7 @@ public void OperatorExpression_Simple()
 
 			Assert.IsTrue(tokenizer.MoveNext());
 
-			TSQLOperatorExpression op = new TSQLOperatorExpressionParser().Parse(
+			TSQLOperationExpression op = new TSQLOperationExpressionParser().Parse(
 				tokenizer,
 				leftSide);
 
@@ -61,8 +61,8 @@ public void OperatorExpression_Simple()
 
 			Assert.AreEqual("+", op.Operator.Text);
 
-			Assert.AreEqual(TSQLExpressionType.Operator, op.RightSide.Type);
-			TSQLOperatorExpression rightSide = op.RightSide.AsOperator;
+			Assert.AreEqual(TSQLExpressionType.Operation, op.RightSide.Type);
+			TSQLOperationExpression rightSide = op.RightSide.AsOperation;
 			TokenComparisons.CompareTokenLists(
 				new List<TSQLToken>()
 					{
diff --git a/TSQL_Parser/Tests/Statements/SelectStatementTests.cs b/TSQL_Parser/Tests/Statements/SelectStatementTests.cs
index a50f681..e37a5a6 100644
--- a/TSQL_Parser/Tests/Statements/SelectStatementTests.cs
+++ b/TSQL_Parser/Tests/Statements/SelectStatementTests.cs
@@ -267,23 +267,23 @@ public void SelectStatement_MultiLevelParens()
 			Assert.AreEqual(TSQLExpressionType.Grouped, lvl1Expression.Type);
 			// contents of outer parens
 			TSQLExpression lvl2Expression = lvl1Expression.AsGrouped.InnerExpression;
-			Assert.AreEqual(TSQLExpressionType.Operator, lvl2Expression.Type);
-			Assert.AreEqual("-", lvl2Expression.AsOperator.Operator.Text);
+			Assert.AreEqual(TSQLExpressionType.Operation, lvl2Expression.Type);
+			Assert.AreEqual("-", lvl2Expression.AsOperation.Operator.Text);
 			// (A/B)
-			TSQLExpression lvl2aExpression = lvl2Expression.AsOperator.LeftSide;
+			TSQLExpression lvl2aExpression = lvl2Expression.AsOperation.LeftSide;
 			// 1
-			TSQLExpression lvl2bExpression = lvl2Expression.AsOperator.RightSide;
+			TSQLExpression lvl2bExpression = lvl2Expression.AsOperation.RightSide;
 			Assert.AreEqual(TSQLExpressionType.Grouped, lvl2aExpression.Type);
 			Assert.AreEqual(TSQLExpressionType.Constant, lvl2bExpression.Type);
 			Assert.AreEqual(1, lvl2bExpression.AsConstant.Literal.AsNumericLiteral.Value);
 			// A/B
 			TSQLExpression lvl3Expression = lvl2aExpression.AsGrouped.InnerExpression;
-			Assert.AreEqual(TSQLExpressionType.Operator, lvl3Expression.Type);
-			Assert.AreEqual("/", lvl3Expression.AsOperator.Operator.Text);
+			Assert.AreEqual(TSQLExpressionType.Operation, lvl3Expression.Type);
+			Assert.AreEqual("/", lvl3Expression.AsOperation.Operator.Text);
 			// A
-			TSQLExpression lvl3aExpression = lvl3Expression.AsOperator.LeftSide;
+			TSQLExpression lvl3aExpression = lvl3Expression.AsOperation.LeftSide;
 			// B
-			TSQLExpression lvl3bExpression = lvl3Expression.AsOperator.RightSide;
+			TSQLExpression lvl3bExpression = lvl3Expression.AsOperation.RightSide;
 			Assert.AreEqual(TSQLExpressionType.Column, lvl3aExpression.Type);
 			Assert.AreEqual("A", lvl3aExpression.AsColumn.Column.Name);
 			Assert.IsNull(lvl3aExpression.AsColumn.TableReference);
@@ -844,5 +844,50 @@ INNER JOIN Sales.SalesOrderDetail AS sod
 			Assert.AreEqual("NonDiscountSales", select.Select.Columns[1].ColumnAlias.Name);
 			Assert.AreEqual("Discounts", select.Select.Columns[2].ColumnAlias.Name);
 		}
+
+		[Test]
+		public void SelectStatement_SELECT_DISTINCT()
+		{
+			// regression test for https://github.com/bruce-dunwiddie/tsql-parser/issues/101
+			List<TSQLStatement> statements = TSQLStatementReader.ParseStatements(
+				@"SELECT 
+					COUNT(DISTINCT id) AssetId_changes
+				FROM [gs].[ESG_ResolvedGSID_Merged]",
+				includeWhitespace: false);
+
+			Assert.AreEqual(1, statements.Count);
+			TSQLSelectStatement select = statements.Single().AsSelect;
+			Assert.AreEqual(11, select.Tokens.Count);
+			Assert.AreEqual(1, select.Select.Columns.Count);
+			Assert.AreEqual("AssetId_changes", select.Select.Columns[0].ColumnAlias.Name);
+			Assert.AreEqual("id", 
+				select
+				.Select
+				.Columns[0]
+				.Expression
+				.AsFunction
+				.Arguments[0]
+				.AsDuplicateSpecification
+				.InnerExpression
+				.AsColumn
+				.Column
+				.Name);
+		}
+
+		[Test]
+		public void SelectStatement_SELECT_NULL()
+		{
+			// regression test for https://github.com/bruce-dunwiddie/tsql-parser/issues/104
+			List<TSQLStatement> statements = TSQLStatementReader.ParseStatements(
+				@"SELECT 1, 2, 3, NULL, 5 FROM MyTable",
+				includeWhitespace: false);
+
+			Assert.AreEqual(1, statements.Count);
+			TSQLSelectStatement select = statements.Single().AsSelect;
+			Assert.AreEqual(12, select.Tokens.Count);
+			Assert.AreEqual(5, select.Select.Columns.Count);
+			Assert.AreEqual(TSQLExpressionType.Null, select.Select.Columns[3].Expression.Type);
+			Assert.AreEqual(5, select.Select.Columns[4].Expression.AsConstant.Literal.AsNumericLiteral.Value);
+		}
 	}
 }
diff --git a/TSQL_Parser/Tests/Tests.csproj b/TSQL_Parser/Tests/Tests.csproj
index fba23c3..6a59a9a 100644
--- a/TSQL_Parser/Tests/Tests.csproj
+++ b/TSQL_Parser/Tests/Tests.csproj
@@ -72,7 +72,7 @@
     <Compile Include="Clauses\SelectClauseTests.cs" />
     <Compile Include="Expressions\ArgumentListTests.cs" />
     <Compile Include="Expressions\CaseExpressionTests.cs" />
-    <Compile Include="Expressions\OperatorExpressionTests.cs" />
+    <Compile Include="Expressions\OperationExpressionTests.cs" />
     <Compile Include="IdentifiersTests.cs" />
     <Compile Include="Parsing.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />