Trigger for update from one database to another database - mysql

Question

I have two different database DB1 and DB2. Each has two different tables Table A and Table B respectively. So in case If any new row generates in table B I want trigger fire which gives me date and time in table A at same time when new row generated in table B. Now I have created one trigger as below but it's working.
DELIMITER $$
USE `DB2`$$
DROP TRIGGER /*!50032 IF EXISTS */ `trigger_update_date_time_table_A`$$
CREATE
/*!50017 DEFINER = 'root'#'%' */
TRIGGER `trigger_update_date_time_tableA` AFTER INSERT ON table_B
FOR EACH ROW
BEGIN
UPDATE DB1.table_A SET Date = CURRENT_TIMESTAMP WHERE id = NEW.id
END;
$$
DELIMITER ;

Answer 1

You are going to have to be a bit more specific about why you think the trigger does not produce the expected results with an example. Here's and example of how you could do that.BTW if you work your way through this you will see the trigger works as coded.
MariaDB [SANDBOX]> USE SANDBOX;
Database changed
MariaDB [SANDBOX]> SHOW CREATE TABLE T;
+-------+---------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------+
| T | CREATE TABLE `t` (
`ID` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+---------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
MariaDB [SANDBOX]> USE TEST;
Database changed
MariaDB [TEST]> SHOW CREATE TABLE TEST.T;
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| T | CREATE TABLE `t` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`price` int(11) DEFAULT NULL,
`tax` int(11) DEFAULT NULL,
`pricetax` int(11) AS (price + price *tax/100) VIRTUAL,
`DATE` date DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1000 DEFAULT CHARSET=latin1 |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
MariaDB [TEST]> USE SANDBOX;
Database changed
MariaDB [SANDBOX]> SHOW CREATE TRIGGER T;
+---------+--------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
| Trigger | sql_mode | SQL Original Statement | character_set_client | collation_connection | Database Collation |
+---------+--------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
| T | STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`#`localhost` TRIGGER T AFTER INSERT ON T
FOR EACH ROW
BEGIN
UPDATE TEST.T SET Date = CURRENT_TIMESTAMP WHERE id = NEW.id ;
END | utf8mb4 | utf8mb4_general_ci | latin1_swedish_ci |
+---------+--------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
1 row in set (0.00 sec)
MariaDB [SANDBOX]> TRUNCATE TABLE T;
Query OK, 0 rows affected (0.22 sec)
MariaDB [SANDBOX]> SELECT * FROM T;
Empty set (0.00 sec)
MariaDB [SANDBOX]> UPDATE TEST.T SET DATE = NULL WHERE ID = 999;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1 Changed: 1 Warnings: 0
MariaDB [SANDBOX]> SELECT ID,DATE FROM TEST.T;
+-----+------+
| ID | DATE |
+-----+------+
| 1 | NULL |
| 999 | NULL |
+-----+------+
2 rows in set (0.00 sec)
MariaDB [SANDBOX]> INSERT INTO T (ID) VALUES (999);
Query OK, 1 row affected (0.02 sec)
MariaDB [SANDBOX]> SELECT ID,DATE FROM TEST.T;
+-----+------------+
| ID | DATE |
+-----+------------+
| 1 | NULL |
| 999 | 2018-09-13 |
+-----+------------+
2 rows in set (0.00 sec)