When selecting using an anonymous type to specify column the anonymous type's property name is now used as the column alias. This allows working with ambiguous column names when joining multiple tables.

Author: shift-evgeny

src/ServiceStack.OrmLite/Expressions/SqlExpression.cs

@@ -1449,13 +1449,22 @@ protected virtual object VisitNew(NewExpression nex)
             if (isAnonType)
             {
                 var exprs = VisitExpressionList(nex.Arguments);
+
                 var r = StringBuilderCache.Allocate();
-                foreach (object e in exprs)
+                for (var i = 0; i < exprs.Count; ++i)
                 {
-                    if (r.Length > 0)
+                    if (i > 0)
                         r.Append(",");
 
-                    r.Append(e);
+                    r.Append(exprs[i]);
+
+                    // Use the anon type property name, rather than the table property name, as the returned column name
+
+                    var propertyExpr = nex.Arguments[i] as MemberExpression;
+                    if (propertyExpr != null && propertyExpr.Member.Name != nex.Members[i].Name)
+                    {
+                        r.Append(" AS " + DialectProvider.GetQuotedName(nex.Members[i].Name));
+                    }
                 }
                 return StringBuilderCache.ReturnAndFree(r);
             }

tests/ServiceStack.OrmLite.Tests/Expression/SqlExpressionTests.cs

@@ -856,6 +856,24 @@ public override bool Equals(object obj)
             }
         }
 
+        private class JoinSelectResults2
+        {
+            // From TableA
+            public int Id { get; set; }
+            public bool Bool { get; set; }
+            public string Name { get; set; }
+
+            // From TableB
+            public int TableBId { get; set; }
+            public string TableBName { get; set; }
+
+            public override bool Equals(object obj)
+            {
+                var other = (JoinSelectResults2)obj;
+                return Id == other.Id && Bool == other.Bool && Name == other.Name && TableBId == other.TableBId && TableBName == other.TableBName;
+            }
+        }
+
         [Test]
         public void Can_select_entire_tables()
         {
@@ -870,21 +888,38 @@ public void Can_select_entire_tables()
                 db.Insert(new TableB { Id = 2, TableAId = 2, Name = "NameB2" });
                 db.Insert(new TableB { Id = 3, TableAId = 2, Name = "NameB3" });
 
-                var q = db.From<TableA>()
-                    .Join<TableB>()
-                    .Select<TableA, TableB>((a, b) => new { a, b.TableAId })
-                    .OrderBy(x => x.Id);
-
                 try
                 {
-                    var rows = db.Select<JoinSelectResults1>(q);
-                    var expected = new[]
+                    // Select all columns from TableA
+
+                    var q1 = db.From<TableA>()
+                        .Join<TableB>()
+                        .Select<TableA, TableB>((a, b) => new { a, b.TableAId })
+                        .OrderBy(x => x.Id);
+
+                    var rows1 = db.Select<JoinSelectResults1>(q1);
+                    var expected1 = new[]
                     {
                         new JoinSelectResults1 { Id = 1, Bool = false, Name = "NameA1", TableAId = 1 },
                         new JoinSelectResults1 { Id = 2, Bool = true, Name = "NameA2", TableAId = 2 },
                         new JoinSelectResults1 { Id = 2, Bool = true, Name = "NameA2", TableAId = 2 },
                     };
-                    Assert.That(rows, Is.EqualTo(expected));
+                    Assert.That(rows1, Is.EqualTo(expected1));
+
+                    // Same, but use column aliases for some columns from TableB whose names would conflict otherwise
+
+                    var q2 = db.From<TableA>()
+                        .Join<TableB>()
+                        .Select<TableA, TableB>((a, b) => new { a, TableBId = b.Id, TableBName = b.Name });
+
+                    var rows2 = db.Select<JoinSelectResults2>(q2).OrderBy(r => r.Id).ThenBy(r => r.TableBId);
+                    var expected2 = new[]
+                    {
+                        new JoinSelectResults2 { Id = 1, Bool = false, Name = "NameA1", TableBId = 1, TableBName = "NameB1" },
+                        new JoinSelectResults2 { Id = 2, Bool = true, Name = "NameA2", TableBId = 2, TableBName = "NameB2" },
+                        new JoinSelectResults2 { Id = 2, Bool = true, Name = "NameA2", TableBId = 3, TableBName = "NameB3" },
+                    };
+                    Assert.That(rows2, Is.EqualTo(expected2));
                 }
                 finally
                 {