擅长:python、mysql、java
<p><code>isouter=True</code>标志将产生一个与<code>LEFT JOIN</code>相同的<code>LEFT OUTER JOIN</code>。</p>
<p>使用您的代码:</p>
<pre><code>(sa.select([idc.c.Code])
.select_from(
t1.join(t2, and_(t1.c.attr == 1, t2.c.attr2 = 1))
.join(t3, t3.c.Code == t1.c.Code, isouter=True)))
</code></pre>
<p>声明性示例:</p>
<pre><code>session = scoped_session(sessionmaker())
session.query(Model).join(AnotherModel, AnotherModel.model_id == Model.id, isouter=True)
</code></pre>