使用子查询和连接表更新临时表失败

Question

我的数据库中有一个评估线表，我想从第一次评估中获取一些数据，并将其与最新评估中的相同数据一起显示，以便轻松查看从第一次评估到当前评估的进展。我正在使用来自两个评估的三个值以及来自当前评估的其他数据来执行此操作。

为此，我认为我需要创建临时表来保存两组字段以及当前评估中的其他字段。

我的临时表创建如下：

CREATE TEMPORARY TABLE appraisal_lines_submitted (
    current_perceived_state INT(2),
    current_actual_state INT(2),
    current_desired_state INT(2),
    agreed_action_points TEXT,
    agreed_actions_target_date DATE,
    assessor_notes TEXT,
    category_id INT(2),
    sub_categories_id INT(2),
    sub_categories_description VARCHAR(45),
    sequence_number INT(3) PRIMARY KEY,
    first_perceived_state INT(2),
    first_actual_state INT(2),
    first_desired_state INT(2)
);

然后我运行如下插入和选择语句，将当前评估中的数据放入临时表中：

INSERT INTO appraisal_lines_submitted (
    current_perceived_state,
    current_actual_state,
    current_desired_state,
    agreed_action_points,
    agreed_actions_target_date,
    assessor_notes,
    category_id,
    sub_categories_id,
    sub_categories_description,
    sequence_number)
SELECT appraisal_lines.perceived_state,
    appraisal_lines.actual_state,
    appraisal_lines.desired_state,
    appraisal_lines.agreed_action_points,
    DATE_FORMAT (appraisal_lines.agreed_actions_target_date, '%d/%m/%Y') AS agreed_actions_target_date_formatted,
    appraisal_lines.assessor_notes,
    appraisal_lines.assessment_category_id,
    assessment_sub_categories.id,
    assessment_sub_categories.description,
    assessment_sub_categories.sequence_number
FROM appraisal_lines LEFT JOIN assessment_sub_categories
    ON appraisal_lines.assessment_sub_category_id = assessment_sub_categories.id
WHERE hyperlink_token ='db678f8595edcd78d8ea7f055f7ee790b804c91e'
    AND assessment_category_id ='5'
ORDER BY sequence_number;

这工作正常。

但是当我运行下面的更新语句时它失败了

UPDATE appraisal_lines_submitted JOIN
    (SELECT appraisal_lines.perceived_state as update_perceived_state
     FROM appraisal_lines
     WHERE hyperlink_token ='d7cc7e1adc116e0dac31cbad34cd9a2b322c3507'
        AND assessment_category_id ='5'
     ORDER BY appraisal_lines.assessment_sub_category_id
    ) AS increments 
    ON increments.update_perceived_state = appraisal_lines.perceived_state
    SET appraisal_lines_submitted.first_perceived_state = update_perceived_state;

出现错误

错误代码：1054
“on 子句”中的未知列“appraisal_lines.perceived_state”

我根据帖子写了更新声明：MySQL Update a field value with subquery with multiple returning rows

Answer 1

这是您的脚本，其中一些以粗体突出显示：

UPDATE appraisal_lines_submitted JOIN
    (SELECT appraisal_lines.perceived_state as update_perceived_state
     FROM appraisal_lines
     WHERE hyperlink_token ='d7cc7e1adc116e0dac31cbad34cd9a2b322c3507'
        AND assessment_category_id ='5'
     ORDER BY appraisal_lines.assessment_sub_category_id
    ) AS increments 
    ON increments.update_perceived_state = appraisal_lines.perceived_state
    SET appraisal_lines_submitted.first_perceived_state = update_perceived_state;

现在，在您的脚本中，您将一个名为 appraisal_lines_submitted 的表连接到一个名为 increments 的（派生）表。连接条件引用来自increments 的列和来自...的列……等一下，appraisal_lines？那是什么？参与加入的人中没有同名的表。

我的猜测是，加入条件中的appraisal_lines.perceived_state 引用应该替换为appraisal_lines_submitted.current_perceived_state。

我的另一个猜测是，您在ORDER BY 之后错过了LIMIT 1，这是基于正在更新的列的名称 (<b>first</b>_perceived_state)

Answer 2

解析器看不到表appraisal_lines，因为您正在更新appraisal_lines_submitted。

您在内部SELECT 中指定appraisal_lines 的唯一位置，别名为increments

您也可以将ORDER BY 放在内部SELECT 中，无论内部数据的顺序如何，都会执行连接。