MySQL INSERT INTO查询列值等于另一个SQL SELECT查询

Question

Could anybody kindly guide me on correct direction for below query? It's not working under phpMyAdmin.

INSERT INTO `Setting` 
(`id`, `type`, `name`, `value`, `parentId`, `createdAt`, `updatedAt`, `createdById`, `updatedById`) 
VALUES 
(NULL, 0, 'howItWorks', 'Some URL', NULL, NULL, NULL, -1, NULL), 
(NULL, 0, 'howItWorksThumb', 'Some URL', (SELECT id FROM Setting WHERE name = 'howItWorks'), NULL, NULL, -1, NULL);

Same kind of query works under PostgreSQL.

Error I am getting: #1093 - You can't specify target table 'Setting' for update in FROM clause

Question is update to explained issues related to LAST_INSERT_ID() solutions:

To use LAST_INSERT_ID() solutions; child row should be inserting immediately after parent row.

I want to get the parentId for child row not immediately after I insert parent row. What will be the solution?

Also what if I want to add two children for same parent row?

Answer 1

MySQL doesn't allow you to SELECT in a subquery from the same table that you're inserting into in the main query. So you'll need to split this into two INSERT queries:

You can use LAST_INSERT_ID() to get the auto-increment ID that was assigned in the last INSERT , rather than using a subquery.

INSERT INTO `Setting` (`id`, `type`, `name`, `value`, `parentId`, `createdAt`, `updatedAt`, `createdById`, `updatedById`) 
    VALUES (NULL, 0, 'howItWorks', 'Some URL', NULL, NULL, NULL, -1, NULL);
INSERT INTO `Setting` (`id`, `type`, `name`, `value`, `parentId`, `createdAt`, `updatedAt`, `createdById`, `updatedById`) 
    VALUES (NULL, 0, 'howItWorksThumb', 'Some URL', LAST_INSERT_ID(), NULL, NULL, -1, NULL);

Unfortunately, using LAST_INSERT_ID() still doesn't allow you to combine them into a single query, because it calls the function before doing any inserts.

If you're doing the second insert later, you can do it with a normal INSERT ... SELECT ... :

INSERT INTO `Setting` (`id`, `type`, `name`, `value`, `parentId`, `createdAt`, `updatedAt`, `createdById`, `updatedById`) 
SELECT NULL, 0, 'howItWorksThumb', 'Some URL', id, NULL, NULL, -1, NULL
FROM Setting
WHERE name = 'howItWorks'

Answer 2

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table 
( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
, type TINYINT NOT NULL
, name VARCHAR(100) NOT NULL
, value VARCHAR(100) NOT NULL
, parentId INT NULL
, createdById INT NOT NULL
);

It would be sensible to bind the following into a transaction.

INSERT INTO my_table 
( type
, name
, value
, createdById
) 
VALUES 
( 0
, 'howItWorks'
, 'Some URL'
, -1
);

INSERT INTO my_table 
( type
, name
, value
, parentId
, createdById
)
SELECT 0
     , 'howItWorksThumb'
     , 'Some URL'
     , LAST_INSERT_ID()
     , -1
  FROM my_table;

End of transaction

  SELECT * FROM my_table;
  +----+------+-----------------+----------+----------+-------------+
  | id | type | name            | value    | parentId | createdById |
  +----+------+-----------------+----------+----------+-------------+
  |  1 |    0 | howItWorks      | Some URL |     NULL |          -1 |
  |  2 |    0 | howItWorksThumb | Some URL |        1 |          -1 |
  +----+------+-----------------+----------+----------+-------------+

Answer 3

see the data type of the table that you created. and see also DEFAULT on the field that you create. If ID is NULL should DEFAULT = auto_increment.