Expressions can be named without the as keyword.

Author: RyanLamansky

SqlServerSimulator.Tests/SelectTests.cs

@@ -59,6 +59,15 @@ public void Expression(string commandText, object value)
     }
 
     [TestMethod]
+    public void BareAs()
+    {
+        var exception = Assert.Throws<DbException>(() => new Simulation().ExecuteScalar("select as z"));
+        Assert.AreEqual("Incorrect syntax near the keyword 'as'.", exception.Message);
+    }
+
+    [TestMethod]
+    [DataRow("select 1", "", 1)]
+    [DataRow("select 1 c", "c", 1)]
     [DataRow("select 1 as c", "c", 1)]
     [DataRow("select 1 as [c]", "c", 1)]
     [DataRow("select 1 as [c]]d]", "c]d", 1)]
@@ -94,6 +103,7 @@ public void ExpressionFromTable(string commandText, int minimumRows, int uniqueR
     }
 
     [TestMethod]
+    [DataRow("select name c from systypes", 34, 34, "c", "image")]
     [DataRow("select name as c from systypes", 34, 34, "c", "image")]
     [DataRow("select name as c from systypes as s", 34, 34, "c", "image")]
     [DataRow("select systypes.name from systypes", 34, 34, "name", "image")]

SqlServerSimulator/Parser/Expression.cs

@@ -102,7 +102,7 @@ public static Expression Parse(ParserContext context)
     /// <param name="expression">The expression to wrap.</param>
     /// <param name="name">The name to assign.</param>
     /// <returns>The named expression.</returns>
-    public static Expression AssignName(Expression expression, string name) => new NamedExpression(expression, name);
+    public static Expression AssignName(Expression expression, Name name) => new NamedExpression(expression, name.Value);
 
     /// <summary>
     /// Runs the expression, returning its result.

SqlServerSimulator/Parser/Selection.cs

@@ -59,6 +59,9 @@ public static Selection Parse(ParserContext context, uint depth)
                 case ReservedKeyword { Keyword: Keyword.From }:
                     break;
 
+                case ReservedKeyword { Keyword: not Keyword.Null } keyword:
+                    throw SimulatedSqlException.SyntaxErrorNearKeyword(keyword);
+
                 case Operator { Character: ',' }:
                     if (expressions.Count == 0)
                         throw SimulatedSqlException.SyntaxErrorNear(context.Token);
@@ -81,14 +84,18 @@ public static Selection Parse(ParserContext context, uint depth)
                 case Operator { Character: ',' }:
                     continue;
 
+                case Name name:
+                    expressions[^1] = Expression.AssignName(expressions.Last(), name);
+                    continue;
+
                 case ReservedKeyword { Keyword: Keyword.As }:
-                    expressions[^1] = Expression.AssignName(expressions.Last(), context.GetNextRequired<StringToken>().Value);
+                    expressions[^1] = Expression.AssignName(expressions.Last(), context.GetNextRequired<Name>());
                     continue;
 
                 case ReservedKeyword { Keyword: Keyword.From }:
                     switch (context.GetNextRequired())
                     {
-                        case StringToken tableName:
+                        case Name tableName:
                             if (!context.Simulation.Tables.TryGetValue(tableName.Value, out var table) && !context.Simulation.SystemTables.Value.TryGetValue(tableName.Value, out table))
                                 throw SimulatedSqlException.InvalidObjectName(tableName);