问题

I have these two tables just for example:

TAB_TEACHER
- id_teacher   // primary key, autoincrement
- name_teacher // a varchar

TAB_STUDENT
- id_student    // primary key, autoincrement
- name_student  // a varchar
- id_teacher_fk // foreign key reference to a teacher (TAB_TEACHER)

I want to know how to insert in these two cases:

CASE 1 - INSERT a new Student with an pre-existing TEACHER, so I have to get the foreign key with a teacher name

CASE 2 - INSERT a new Student with a new TEACHER (the teacher I'm creating in the same time I'm creating the student)

回答1:

http://dev.mysql.com/doc/refman/5.0/en/insert-select.html

For case1:

INSERT INTO TAB_STUDENT(name_student, id_teacher_fk)
SELECT 'Joe The Student', id_teacher
  FROM TAB_TEACHER
 WHERE name_teacher = 'Professor Jack'
 LIMIT 1

For case2 you just have to do 2 separate insert statements

回答2:

Case 1: Insert Row and Query Foreign Key

Here is an alternate syntax I use:

INSERT INTO tab_student 
   SET name_student = 'Bobby Tables',
       id_teacher_fk = (
       SELECT id_teacher
         FROM tab_teacher
        WHERE name_teacher = 'Dr. Smith')

I'm doing this in Excel to import a pivot table to a dimension table and a fact table in SQL so you can import to both department and expenses tables from the following:

Case 2: Insert Row and Then Insert Dependant Row

Luckily, MySQL supports LAST_INSERT_ID() exactly for this purpose.

INSERT INTO tab_teacher
   SET name_teacher = 'Dr. Smith';
INSERT INTO tab_student 
   SET name_student = 'Bobby Tables',
       id_teacher_fk = LAST_INSERT_ID()

回答3:

Case 1

INSERT INTO tab_student (name_student, id_teacher_fk)
    VALUES ('dan red', 
           (SELECT id_teacher FROM tab_teacher WHERE name_teacher ='jason bourne')

it is advisable to store your values in lowercase to make retrieval easier and less error prone

Case 2

mysql docs

INSERT INTO tab_teacher (name_teacher) 
    VALUES ('tom stills')
INSERT INTO tab_student (name_student, id_teacher_fk)
    VALUES ('rich man', LAST_INSERT_ID())

来源：https://stackoverflow.com/questions/4775520/how-to-insert-values-in-table-with-foreign-key-using-mysql

标签

mysql

insert

foreign-keys

How to insert values in table with foreign key using MySQL?

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