你的 SQL 应该是这样的

DELETE FROM `course` WHERE `course_id`="BIO-399" AND `title`="Computational Biology" AND `credits` ="4";

分解：

Delete from table-name where condition

将从表中删除行 table-name 满足之后提供的条件 where 条款
条件是 column-name = value .

DELETE 
FROM course 
WHERE course_id="BIO-399" AND title = "Computational Biology" AND credits ="4";

MariaDB [sandbox]> drop table if exists school_course,school_section;
Query OK, 0 rows affected (0.19 sec)

MariaDB [sandbox]> create table school_course (id int, name varchar(2));
Query OK, 0 rows affected (0.23 sec)

MariaDB [sandbox]> create table school_section(id int, cid int, name varchar(2));
Query OK, 0 rows affected (0.20 sec)

MariaDB [sandbox]>
MariaDB [sandbox]> insert into school_course values (1,'c1'),(2,'c2');
Query OK, 2 rows affected (0.02 sec)
Records: 2  Duplicates: 0  Warnings: 0

MariaDB [sandbox]> insert into school_section values (1,1,'s1');
Query OK, 1 row affected (0.05 sec)

MariaDB [sandbox]>
MariaDB [sandbox]> select sc.*, ss.*
    -> from school_course sc
    -> left join school_section ss on ss.cid = sc.id;
+------+------+------+------+------+
| id   | name | id   | cid  | name |
+------+------+------+------+------+
|    1 | c1   |    1 |    1 | s1   |
|    2 | c2   | NULL | NULL | NULL |
+------+------+------+------+------+
2 rows in set (0.00 sec)

MariaDB [sandbox]>
MariaDB [sandbox]> delete sc
    -> from school_course sc
    -> left join school_section ss on ss.cid = sc.id
    -> where ss.cid is null;
Query OK, 1 row affected (0.05 sec)

MariaDB [sandbox]>
MariaDB [sandbox]> select sc.*, ss.*
    -> from school_course sc
    -> left join school_section ss on ss.cid = sc.id;
+------+------+------+------+------+
| id   | name | id   | cid  | name |
+------+------+------+------+------+
|    1 | c1   |    1 |    1 | s1   |
+------+------+------+------+------+
1 row in set (0.00 sec)

试试这个：

delete from course where course_id in
(select distinct course.course_id
from course, section
where course.course_id not in (select course_id from section));

据我所知，你不需要加入这个查询的课程和部分。
请尝试此操作，看看是否得到相同的结果：

select distinct course.course_id
from course
where course.course_id not in (select course_id from section)

如果是，则使用此查询删除：

delete from course where course_id in
(select distinct course.course_id
from (select * from course) as c
where c.course_id not in (select course_id from section));

您可以通过使用sql的join概念来尝试这一点。这里我们将使用左连接。

delete course from 
course left join section on course.course_id = section.course_id 
where course.course_id = NULL;

注意：这里我假设course\u id像外键一样出现在两个表中，如果不是，您能共享两个表的模式以更清晰吗？
希望这有帮助