多到一个在风暴

Question

属性

我的模式看起来是这样的：

CREATE TABLE plans (
    id SERIAL PRIMARY KEY, 
    description text 
); 

CREATE TABLE projects (
    id SERIAL PRIMARY KEY, 
    project_id character varying(240) UNIQUE, 
    plan_id integer REFERENCES plans(id) ON DELETE CASCADE 
); 

我想要做的风暴查询沿

plan = store.find(Plan, Plan.project_id == "alpha") 
# should translate to something like 
# SELECT p.* from plans p LEFT JOIN projects proj ON p.id = proj.plan_id 
#  WHERE proj.project_id = 'alpha'; 

线（注意projects.plan_id不是唯一）

我该如何设置？

Answer 1

对于给定的SQL，没有太多理由使用左连接，因为where子句不会匹配没有相应项目的任何行。你可以得到结果：

result = store.find(Plan, Plan.id == Project.plan_id, Project.project_id == "alpha") 

这会给你一个ResultSet对象。鉴于您的架构，它看起来像你期待单行，这样你就可以访问具有：

plan = result.one() 

或用绑在一起，他们两个：

plan = store.find(Plan, Plan.id == Project.plan_id, Project.project_id == "alpha").one() 

如果你真的需要做左连接，语法是这样的：

result = store.using(LeftJoin(Plan, Project, Plan.id == Project.plan_id)).find(
    Plan, Project.project_id == "alpha")