I have two MySQL tables with an one-to-many relationship between them. For example:
CREATE TABLE test1 (
pk1 INTEGER AUTO_INCREMENT PRIMARY KEY,
testvalue1 INTEGER
);
CREATE TABLE test2 (
pk2 INTEGER AUTO_INCREMENT PRIMARY KEY,
testvalue2 VARCHAR(50),
fk2 INTEGER NOT NULL,
FOREIGN KEY (fk2) REFERENCES test1 (pk1)
);
If I want to insert records in both tables I can first insert a record in the PK table (e.g. INSERT INTO test1 SET testvalue1=100
), determine the PK value (e.g. SELECT MAX(pk1) AS LastId FROM test1
or use LAST_INSERT_ID()
)
and finally use that value to fill the FK column in the second table.
But is it possible 开发者_开发技巧to achieve this all in 1 command/query/action? So let's MySQL fill in the PK- and FK-values using the AUTO INCREMENTs?
You should use two INSERT commands; or try to use an INSERT-trigger.
EDIT:
--An example with trigger:
CREATE TABLE dept(
id INT(11) NOT NULL AUTO_INCREMENT,
dept_name VARCHAR(255) DEFAULT NULL,
PRIMARY KEY (id)
)
ENGINE = INNODB;
CREATE TABLE emp(
id INT(11) NOT NULL AUTO_INCREMENT,
emp_name VARCHAR(255) DEFAULT NULL,
dept_id INT(11) DEFAULT NULL,
PRIMARY KEY (id),
CONSTRAINT FK_emp_dept_id FOREIGN KEY (dept_id)
REFERENCES dept (id) ON DELETE RESTRICT ON UPDATE RESTRICT
)
ENGINE = INNODB;
DELIMITER $$
CREATE TRIGGER trigger1
AFTER INSERT
ON dept
FOR EACH ROW
BEGIN
INSERT INTO emp VALUES (NULL, 'Someone', NEW.id);
END
$$
DELIMITER ;
-- Try to add new department.
INSERT INTO dept VALUES(NULL, 'Sales');
-- Is there new default employee?
SELECT * FROM emp;
+----+----------+---------+
| id | emp_name | dept_id |
+----+----------+---------+
| 1 | Someone | 1 |
+----+----------+---------+
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