如果选择值大于0，则MySql内部联接

我遇到以下问题，我想进行一个查询，该查询将返回我的表计划信息。它看起来类似于此：

+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+-----------+-------------+---------+
| logs_id | plan_id | workout_id | plan_day | date_made           | workout_names_id | name         | language | workout_id | plan_names_id | name      | language_id | plan_id |
+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+-----------+-------------+---------+
|       2 |       1 |          1 |        1 | 2017-04-30 11:40:48 |                2 | Workout GR 1 |        2 |          1 |             2 | Plan 1 GR |           2 |       1 |
+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+-----------+-------------+---------+
1 row in set (0.00 sec)

我的问题是，当计划id没有值时，我什么也得不到，我如何得到一个查询，即使计划id为0，它也会返回一些数据。 这是我迄今为止所编写的代码：

DELIMITER $$
CREATE PROCEDURE get_logs(IN _language SMALLINT(255))
BEGIN

SELECT * FROM logs AS lo INNER JOIN workout_names AS wn ON lo.workout_id = wn.workout_id INNER JOIN plan_names AS pn ON lo.plan_id = pn.plan_id WHERE wn.language = _language AND pn.language_id = _language ORDER BY lo.logs_id;

END$$

当计划id中没有值时，它不会返回任何内容

更新

以下代码适用于部分问题：

DELIMITER $$
CREATE PROCEDURE get_logs(IN _language SMALLINT(255))
BEGIN

SELECT * FROM logs AS lo INNER JOIN workout_names AS wn ON lo.workout_id = wn.workout_id LEFT JOIN plan_names AS pn ON lo.plan_id = pn.plan_id WHERE wn.language = _language AND pn.language_id = _language ORDER BY lo.logs_id;


END$$

如果pn.language\u id=\u language中的值不为null，我该如何执行此操作。我已经知道pn.language\u id=\u language不为null，但它会返回以下内容：

+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+-----------+-------------+---------+
| logs_id | plan_id | workout_id | plan_day | date_made           | workout_names_id | name         | language | workout_id | plan_names_id | name      | language_id | plan_id |
+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+-----------+-------------+---------+
|       3 |       1 |          1 |        1 | 2017-04-30 12:20:47 |                1 | Workout EN 1 |        1 |          1 |             1 | Plan 1 EN |           1 |       1 |
|       3 |       1 |          1 |        1 | 2017-04-30 12:20:47 |                1 | Workout EN 1 |        1 |          1 |             2 | Plan 1 GR |           2 |       1 |
+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+-----------+-------------+---------+
2 rows in set (0.00 sec)

基本上，我只解析一种语言，它得到的是所有语言，它不会返回空的语言。但如果我添加为空，它会返回：

+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+------+-------------+---------+
| logs_id | plan_id | workout_id | plan_day | date_made           | workout_names_id | name         | language | workout_id | plan_names_id | name | language_id | plan_id |
+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+------+-------------+---------+
|       1 |       0 |          1 |        0 | 2017-04-30 10:52:24 |                1 | Workout EN 1 |        1 |          1 |          NULL | NULL |        NULL |    NULL |
+---------+---------+------------+----------+---------------------+------------------+--------------+----------+------------+---------------+------+-------------+---------+
1 row in set (0.00 sec)

我怎样才能将它们结合起来像一个一样工作呢？

就是这样

DELIMITER $$
    CREATE PROCEDURE get_logs(IN _language SMALLINT(255))
    BEGIN

    SELECT * FROM logs AS lo INNER JOIN workout_names AS wn ON lo.workout_id = wn.workout_id LEFT JOIN plan_names AS pn ON lo.plan_id = pn.plan_id AND pn.language_id = _language WHERE wn.language = _language ORDER BY lo.logs_id;


    END$$

---

为什么否决投票？因为您的问题不清楚。您的查询返回的计划名称为

name

，您还想要什么？计划名称和计划id是可选的，如果没有值，我希望能够进行查询。嗯，您正在加入计划名称。所以pn.name已经存在了。因此，只需显式地选择所需的字段，而不是*。如果您希望plan_id为空，请使用左联接来连接plan_名称。