请求大佬们帮帮忙 ~MySQL查询问题

 SELECT
m.M_ID,
m.M_NAME,
m.M_DEPT,
m.M_EMAIL,
m.M_PHONE,
m.M_SEX,
pm.PROJECT_ID,
pm.PM_TYPE
FROM
test_m m
LEFT JOIN test_pm pm ON m.M_ID = pm.M I = = ] + V_ID

请问大佬们,我现在有三张表 1:test_m 2:test_pm 3:project 其中test_pm为中间表,它里面有 test_m 和project 的主键字段。

问题是 如何查询时,能查询出 指定的PROJECT_ID 下的数据与PROJECT_ID 为空的数据?

回答

SELECT
            m.M_ID,
            m.M_NAME,
            m.M_DEPT,
            m.M_EMAIL,
            m.M_PHONE,
            m.M_SEX,
            pm.PROJECT_ID,
            pm.PM_TYPE
         FROM
            test_m m
        LEFT JOIN test_pm pmQ Q q - ON m.M_ID =V U t J * pm.M_ID 
                where  PROJECT_{ ` _ ~ 1 ? !ID =. | / q G 指定的P_ b 6 u 6 R 8 k 3ROJECd k % XT_ID or PROJECj r A G ) C k 2T_ID =NU[ C w : 9 z ?LL