請幫我寫一個mysql查詢來選擇特定部門的成員

比方說，我有2個表，employee和department,department有2個部門，dpt1和dpt2，有12個員工，6個部門和4個部門屬於這兩個部門。我如何使用mysql查詢來查找僅屬於dpt2而不屬於dpt1的員工？請幫我寫一個mysql查詢來選擇特定部門的成員

來源

2011-02-07 Bluemagica

你如何設計員工和部門之間的連接，你有單獨的表多對多的關係，或與「DEP1，DEPT2」價值員工只是場？ – bensiu 2011-02-07 13:21:29

SELECT employee.* 
FROM employee 
INNER JOIN employee_belongs_to_departments 
WHERE employee.id = employee_belongs_to_departments.employee_id 
AND employee_belongs_to_departments.department_id = 'dpt2' 
AND employee.id NOT IN (
    SELECT DISTINCT ebtd2.employee_id 
    FROM employee_belongs_to_departments ebtd2 
    WHERE ebtd2.employee_id = employee.id 
    AND ebtd2.department_id = 'dpt1' 
)

來源

2011-02-07 13:25:18 PatrikAkerstrand

在這種情況下通常的做法是將有第三個「連接」表，稱爲像employeeDepartment。

CREATE TABLE employeeDepartment (
    employee INT UNSIGNED NOT NULL, 
    department INT UNSIGNED NOT NULL, 
    PRIMARY KEY (employee, department) 
)

，然後你也會讓employee和department外鍵到相應的表的主鍵，不過這需要你使用正確的存儲引擎（不，這是很難做到）是。

這使得做各種事情比您似乎要做的方法（將值列表存儲在一列中）容易得多。

然後，您可以使用

SELECT 
    eD1.employee 
FROM 
    employeeDepartment AS eD1 
    LEFT JOIN employeeDepartment AS eD2 ON 
     eD1.employee = eD2.employee AND 
     eD2.department = 'dpt2' -- replace with appropriate integer 
           -- if using integers as I suggested 
WHERE 
    eD1.department = 'dpt1' AND -- same comment applies 
    eD2.employee IS NULL

來源

2011-02-07 13:42:55 Hammerite

請幫我寫一個mysql查詢來選擇特定部門的成員

回答

相關問題