PostgreSQL 用户定义类型成员比较

Question

我有下表定义:

 CREATE TYPE product_limit_type AS (
    product_code varchar(5),
    limit_type varchar(30),
    limit_value numeric(4,0)
);

CREATE TABLE rule_locks (
    session_id bigint,
    rule_id bigint,
    product_limit product_limit_type
);

当我执行以下查询时:

DELETE FROM rule_locks
WHERE (session_id=session_id_ AND product_limit.product_code=product_code_);

我从服务器收到这个错误:

ERROR:  missing FROM-clause entry for table "product_limit"
LINE 1: ...FROM rule_locks WHERE (session_id=session_id_ AND product_li...
                                                         ^

session_id_和product_code_是对应类型的预初始化变量。

如何删除/修改单元格成员变量满足给定条件的行？

Answer 1

字段名称周围应该有括号以访问其子字段，如:

DELETE FROM rule_locks WHERE (session_id=session_id_
     AND (product_limit).product_code=product_code_);

参见 Accessing Composite Types在文档中。