mysql表連接：多個連接到同一個表，但具有不同的參數

-1

我對我的mysql數據庫有以下查詢。mysql表連接：多個連接到同一個表，但具有不同的參數

SELECT 
    mn.id, 
    mn.created_date, 
    mn.created_by, 
    mnt.description, 
    u.handle, 
    mn.admin_request_company_id 
FROM member_notification mn, 
    member_notification_type mnt, 
    member m, 
    user u 
WHERE mn.member_notification_type_id = mnt.id 
    AND mnt.name = 'COMPANYVALIDATION' 
    AND mn.created_by = m.id 
    AND m.user_id = u.id;

這是工作的罰款，但是我現在需要擴展這個去得到一個公司的名字了另一個表。問題是要做到這一點，我需要重新加入成員表使用密鑰 mn.admin_request_company_id，但我不知道如何去做這件事。

我試過創建一個成員m2表，但我收到錯誤。我試圖做到的，是沿着下面的僞代碼的東西線：

SELECT 
    mn.id, 
    mn.created_date, 
    mn.created_by, 
    mnt.description, 
    u.handle, 
    mn.admin_request_company_id, 
    /*c.company_name*/ 
FROM member_notification mn, 
    member_notification_type mnt, 
    member m, 
    /*member m2,*/ 
    /*company c,*/ 
    /*user u*/ 
WHERE mn.member_notification_type_id = mnt.id 
    AND mnt.name = 'COMPANYVALIDATION' 
    AND mn.created_by = m.id 
    AND m.user_id = u.id 
    /* AND mn.admin_request_company_id = m2.company_id 
    AND m2.company_id = c.id*/

編輯的表結構是如下：

CREATE TABLE member_notification (
id INT NOT NULL AUTO_INCREMENT, 
item_id INT NULL, 
member_id INT NULL, 
text VARCHAR(1) NOT NULL, 
member_notification_type_id INT NULL, 
marked_read VARCHAR(1) NOT NULL, 
created_date DATETIME NOT NULL, 
created_by VARCHAR(50) NOT NULL, 
admin_request_company_id INT NULL, 
PRIMARY KEY (id) 
) ENGINE=innodb; 

CREATE TABLE member_notification_type (
id INT NOT NULL AUTO_INCREMENT, 
name VARCHAR(20) NOT NULL, 
description VARCHAR(50) NULL, 
PRIMARY KEY (id) 
) ENGINE=innodb; 

CREATE TABLE member (
id INT NOT NULL AUTO_INCREMENT, 
user_id INT NULL, 
company_id INT NULL, 
soft_delete VARCHAR(10) DEFAULT 'N', 
member_status_id INT NOT NULL, 
PRIMARY KEY (id) 
) ENGINE=innodb; 


CREATE TABLE user (
id INT NOT NULL AUTO_INCREMENT, 
handle VARCHAR(50) NOT NULL, 
first_name VARCHAR(50) NOT NULL, 
last_name VARCHAR(50) NOT NULL, 
date_of_birth VARCHAR(50) NULL, 
soft_delete VARCHAR(10) DEFAULT 'N', 
PRIMARY KEY (id) 
) ENGINE=innodb; 

CREATE TABLE company (
id INT NOT NULL AUTO_INCREMENT, 
owning_company_id INT NULL, 
company_type_id INT NULL, 
name VARCHAR(50) NOT NULL, 
company_details_id INT NULL, 
PRIMARY KEY (id) 
) ENGINE=innodb;

來源

2013-01-22 sapatos

什麼是你的表結構 –

嗯大膽似乎並沒有工作，但增加的部分是**評論 – sapatos

你能提供你的錯誤之間？ –

看起來好像你只是想使用下面的只是增加一個seco次加入到member表：

SELECT 
    mn.id, 
    mn.created_date, 
    mn.created_by, 
    mnt.description, 
    u.handle, 
    mn.admin_request_company_id, 
    c.name 
FROM member_notification mn 
INNER JOIN member_notification_type mnt 
    on mn.member_notification_type_id = mnt.id 
INNER JOIN member m1 
    on mn.created_by = m1.id 
INNER JOIN user u 
    on m1.user_id = u.id 
INNER JOIN member m2 
    on mn.admin_request_company_id = m2.company_id 
INNER JOIN company c 
    on m2.company_id = c.id 
WHERE mnt.name = 'COMPANYVALIDATION'

注意，我改變了電流WHERE條款中加入以ANSI連接語法。我還在表格之間使用了INNER JOIN，您可能需要使用LEFT JOIN。

來源

2013-01-22 11:04:47 Taryn

感謝bluefeet，那看起來像我在找什麼 – sapatos

美麗的工作一個小小的修改款待感謝 – sapatos

要在一個表連接兩次，選擇該表兩次使用不同的名稱：

SELECT 
    ... 
FROM 
    member m1, 
    member m2, 
    someCouplingTable t 
WHERE 
    m1.Id = t.leftId 
    AND m2.Id = t.rightId

來源

2013-01-22 11:00:36 Sjoerd

這裏是你如何能做到這

SELECT 
    mn.id, 
    mn.created_date, 
    mn.created_by, 
    mnt.description, 
    u.handle, 
    mn.admin_request_company_id 
FROM member_notification mn 
    left join member_notification_type mnt 
    on mnt.id = mn.member_notification_type_id 
    left join member m 
    on m.id = mn.created_by 
    left join user u 
    on u.id = m.user_id 
    left join company as c 
    on c.id = m.company_id 
where mnt.name = 'COMPANYVALIDATION'

來源

2013-01-22 11:08:25

mysql表連接：多個連接到同一個表，但具有不同的參數

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