diff --git a/angel_orm/CHANGELOG.md b/angel_orm/CHANGELOG.md
index cc359b6c..d92ba10f 100644
--- a/angel_orm/CHANGELOG.md
+++ b/angel_orm/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 2.1.0-beta.1
+* Calls to `leftJoin`, etc. alias all fields in a child query, to prevent
+`ambiguous column a0.id` errors.
+
 # 2.1.0-beta
 * Split the formerly 600+ line `src/query.dart` up into
 separate files.
diff --git a/angel_orm/lib/src/join_builder.dart b/angel_orm/lib/src/join_builder.dart
index bf5836dd..8a6a3ef0 100644
--- a/angel_orm/lib/src/join_builder.dart
+++ b/angel_orm/lib/src/join_builder.dart
@@ -6,6 +6,7 @@ class JoinBuilder {
   final JoinType type;
   final Query from;
   final String key, value, op, alias;
+  final bool aliasAllFields;
 
   /// A callback to produces the expression to join against, i.e.
   /// a table name, or the result of compiling a query.
@@ -13,34 +14,37 @@ class JoinBuilder {
   final List<String> additionalFields;
 
   JoinBuilder(this.type, this.from, this.to, this.key, this.value,
-      {this.op = '=', this.alias, this.additionalFields = const []}) {
+      {this.op = '=',
+      this.alias,
+      this.additionalFields = const [],
+      this.aliasAllFields = false}) {
     assert(to != null,
         'computation of this join threw an error, and returned null.');
   }
 
   String get fieldName {
-    var right = '$to.$value';
-    if (alias != null) right = '$alias.$value';
+    var v = value;
+    if (aliasAllFields) {
+      v = '${alias}_$v';
+    }
+    var right = '${from.tableName}.$v';
+    if (alias != null) right = '$alias.$v';
     return right;
   }
 
   String nameFor(String name) {
-    var right = '$to.$name';
+    if (aliasAllFields) name = '${alias}_$name';
+    var right = '${from.tableName}.$name';
     if (alias != null) right = '$alias.$name';
     return right;
   }
 
   String compile(Set<String> trampoline) {
     var compiledTo = to();
-    if (compiledTo == null) {
-      print(
-          'NULLLLL $to; from $from; key: $key, value: $value, addl: $additionalFields');
-    }
     if (compiledTo == null) return null;
     var b = StringBuffer();
     var left = '${from.tableName}.$key';
     var right = fieldName;
-
     switch (type) {
       case JoinType.inner:
         b.write(' INNER JOIN');
diff --git a/angel_orm/lib/src/query.dart b/angel_orm/lib/src/query.dart
index ce066897..d38ea343 100644
--- a/angel_orm/lib/src/query.dart
+++ b/angel_orm/lib/src/query.dart
@@ -151,10 +151,17 @@ abstract class Query<T, Where extends QueryWhere> extends QueryBase<T> {
 
     var to = _compileJoin(tableName, trampoline);
     if (to != null) {
+      var alias = _joinAlias(trampoline);
+      if (tableName is Query) {
+        for (var field in tableName.fields) {
+          tableName.aliases[field] = '${alias}_$field';
+        }
+      }
       _joins.add(JoinBuilder(type, this, to, localKey, foreignKey,
           op: op,
-          alias: _joinAlias(trampoline),
-          additionalFields: additionalFields));
+          alias: alias,
+          additionalFields: additionalFields,
+          aliasAllFields: tableName is Query));
     }
   }
 
@@ -228,6 +235,13 @@ abstract class Query<T, Where extends QueryWhere> extends QueryBase<T> {
         var ss = includeTableName ? '$tableName.$s' : s;
         var cast = casts[s];
         if (cast != null) ss = 'CAST ($ss AS $cast)';
+        if (aliases.containsKey(s)) {
+          if (cast != null) {
+            ss = '($ss) AS ${aliases[s]}';
+          } else {
+            ss = '$ss AS ${aliases[s]}';
+          }
+        }
         return ss;
       }));
       _joins.forEach((j) {
diff --git a/angel_orm/lib/src/query_base.dart b/angel_orm/lib/src/query_base.dart
index 8e378636..23ae1720 100644
--- a/angel_orm/lib/src/query_base.dart
+++ b/angel_orm/lib/src/query_base.dart
@@ -7,6 +7,9 @@ abstract class QueryBase<T> {
   /// Casts to perform when querying the database.
   Map<String, String> get casts => {};
 
+  /// `AS` aliases to inject into the query, if any.
+  Map<String, String> aliases = {};
+
   /// Values to insert into a prepared statement.
   final Map<String, dynamic> substitutionValues = {};
 
@@ -21,7 +24,12 @@ abstract class QueryBase<T> {
   /// A String of all [fields], joined by a comma (`,`).
   String get fieldSet => fields.map((k) {
         var cast = casts[k];
-        return cast == null ? k : 'CAST ($k AS $cast)';
+        if (!aliases.containsKey(k)) {
+          return cast == null ? k : 'CAST ($k AS $cast)';
+        } else {
+          var inner =  cast == null ? k : '(CAST ($k AS $cast))';
+          return '$inner AS ${aliases[k]}';
+        }
       }).join(', ');
 
   String compile(Set<String> trampoline,
diff --git a/angel_orm/pubspec.yaml b/angel_orm/pubspec.yaml
index dcd2ba3e..409ebfb1 100644
--- a/angel_orm/pubspec.yaml
+++ b/angel_orm/pubspec.yaml
@@ -1,5 +1,5 @@
 name: angel_orm
-version: 2.1.0-beta
+version: 2.1.0-beta.1
 description: Runtime support for Angel's ORM. Includes base classes for queries.
 author: Tobe O <thosakwe@gmail.com>
 homepage: https://github.com/angel-dart/orm