In MySQL, how do I embed only when the row does not exist and is updated only if the existing version is smaller

Question

I am looking for a way to only insert when a row does not exist in MySQL, and update when a row exists, and the version of the existing row is less than (or equal to) the version of the new row.

For example, a table is defined as:

CREATE TABLE documents (
  id VARCHAR(64) NOT NULL,
  version BIGINT UNSIGNED NOT NULL,
  data BLOB,
  PRIMARY KEY (id)
);

And contains the following data:

id  version  data
----------------------------
1   3        first data set
2   2        second data set
3   5        third data set

And I want to join the following table (column UPDATE: id is unique):

id  version  data
----------------------------
1   4        updated 1st
3   3        updated 2nd
4   1        new 4th

And this should lead to the following (UPDATE: see how only 1 is updated and 4 is inserted):

id  version  data
----------------------------
1   4        updated 1st
2   2        second data set
3   5        third data set
4   1        new 4th

I looked at the INSERT ... ON DUPLICATE KEY UPDATE ... expression, but that doesn't allow the WHERE clause. In addition, I cannot use REPLACE because it also does not allow WHERE. Is this possible with a single MySQL statement?

Java / , PreparedStatement (addBatch). .

UPDATE: PreparedStatement Java? , .

Answer 1

, - INSERT ON DUPLICATE KEY UPDATE.

INSERT INTO table1 SELECT * FROM table2 ON DUPLICATE KEY UPDATE table1.data=IF(table1.version > table2.version, table1.data, table2.data), table1.version=IF(table1.version > table2.version, table1.version, table2.version)

, , .

Answer 2

EDIT: , (id, version) , . id.

---

REPLACE :

REPLACE INTO main 
SELECT  IFNULL(m.id, s.id) id, 
        IFNULL(m.version, s.version) version, 
        IFNULL(m.data, s.data) data
FROM       secondary s
LEFT JOIN  main m ON (m.id = s.id AND m.version > s.version);

:

CREATE TABLE main ( 
   id int, 
   version int, 
   data varchar(50), 
   PRIMARY KEY (id)
);

CREATE TABLE secondary (id int, version int, data varchar(50));

INSERT INTO main VALUES (1, 3, 'first data set');
INSERT INTO main VALUES (2, 2, 'second data set');
INSERT INTO main VALUES (3, 5, 'third data set');

INSERT INTO secondary VALUES (1, 4, 'updated 1st');
INSERT INTO secondary VALUES (3, 3, 'udated 2nd');
INSERT INTO secondary VALUES (4, 1, 'new 4th');

:

SELECT * FROM main;
+----+---------+-----------------+
| id | version | data            |
+----+---------+-----------------+
|  1 |       4 | updated 1st     |
|  2 |       2 | second data set |
|  3 |       5 | third data set  |
|  4 |       1 | new 4th         |
+----+---------+-----------------+
4 rows in set (0.00 sec)

, , REPLACE, :

SELECT     s.id s_id, s.version s_version, s.data s_data,
           m.id m_id, m.version m_version, m.data m_data
FROM       secondary s
LEFT JOIN  main m ON (m.id = s.id AND m.version > s.version);

+------+-----------+-------------+------+-----------+----------------+
| s_id | s_version | s_data      | m_id | m_version | m_data         |
+------+-----------+-------------+------+-----------+----------------+
|    1 |         4 | updated 1st | NULL |      NULL | NULL           |
|    3 |         3 | udated 2nd  |    3 |         5 | third data set |
|    4 |         1 | new 4th     | NULL |      NULL | NULL           |
+------+-----------+-------------+------+-----------+----------------+
3 rows in set (0.00 sec)

IFNULL() , "" , , id = 3, version = 5. :

SELECT  IFNULL(m.id, s.id) id, 
        IFNULL(m.version, s.version) version, 
        IFNULL(m.data, s.data) data
FROM       secondary s
LEFT JOIN  main m ON (m.id = s.id AND m.version > s.version);

+------+---------+----------------+
| id   | version | data           |
+------+---------+----------------+
|    1 |       4 | updated 1st    |
|    3 |       5 | third data set |
|    4 |       1 | new 4th        |
+------+---------+----------------+
3 rows in set (0.00 sec)

, - , . , REPLACE.