Adding join and fixing a bug with chaining dynamic parameters.

Dapper.Contrib/SqlMapperExtensions.cs

@@ -563,10 +563,15 @@ public SqlBuilder Select(string sql, dynamic parameters = null)
             return this;
         }
 
-        string parameterClause = Guid.NewGuid().ToString();
         public SqlBuilder AddParameters(dynamic parameters)
         {
-            AddClause(parameterClause, "", parameters, "");
+            AddClause("--parameters", "", parameters, "");
+            return this;
+        }
+
+        public SqlBuilder Join(string sql, dynamic parameters = null)
+        {
+            AddClause("join", sql, parameters, joiner: "\nJOIN ", prefix: "\nJOIN", postfix: "\n");
             return this;
         }
     }

Dapper/SqlMapper.cs

@@ -1698,15 +1698,38 @@ object param
 #else
             dynamic param
 #endif
-            )
+)
         {
             object obj = param as object;
 
             if (obj != null)
+            {
+                var subDynamic = obj as DynamicParameters;
+
+                if (subDynamic == null)
                 {
                     templates = templates ?? new List<object>();
                     templates.Add(obj);
                 }
+                else
+                {
+                    if (subDynamic.parameters != null)
+                    {
+                        foreach (var kvp in subDynamic.parameters)
+                        {
+                            parameters.Add(kvp.Key, kvp.Value);
+                        }
+                    }
+
+                    if (subDynamic.templates != null)
+                    {
+                        foreach (var t in subDynamic.templates)
+                        {
+                            templates.Add(t);
+                        }
+                    }
+                }
+            }
         }