I'm running a wateranalyzer and want to save the sensor-data in a MariaDB.
I split the data into 2 tables: one for the automated part and one table which stores data I enter manually:
Tables:
I'm having a hard time (with just basic knowledge about databases) to figure out how I can "bind" ID and DateTime from one table to the other one, so if manual data is added, ID is incremented by 1 and the actual Date and Time is set in DateTime.
I bet I can do this somehow in PHPmyadmin?
thanks for your time!
using triger. this example for you.
DELIMITER //
CREATE TRIGGER contacts_after_insert
AFTER INSERT
ON contacts FOR EACH ROW
BEGIN
DECLARE vUser varchar(50);
-- Find username of person performing the INSERT into table
SELECT USER() INTO vUser;
-- Insert record into audit table
INSERT INTO contacts_audit
( contact_id,
deleted_date,
deleted_by)
VALUES
( NEW.contact_id,
SYSDATE(),
vUser );
END; //
DELIMITER ;
Is it anything more complex than having an ID in Wasser that matches the other ID? That is, first insert into Luft, then get the id and only then, INSERT INTO Wasser....
(A Trigger seems unnecessarily complicated.)
As Rick Suggested, you need to have an ID column in the second table that references ID in first table. Trigger is a better option if the process of getting the ID and inserting it along with other columns (pH, Redox...) into the second table is complicated.
Make ID in the second table as a foreign key to the ID in first table.
Related
At a high level I am already aware that you can not insert a new row to the same table and that one should consider a SPROC. Here is the use case though. There is a 3rd party web app and this MySQL DB that I have, so I have no control over the application flow. A request has come in to simplify data entry. What I do have control over is the database. The app is like a CRM and has a contacts table and there is a 2nd contact_relationships table where I am putting the trigger on. Basically the contact_relationships needs three fields. Two contactIDs (INT) from the contact table and a relationship_type varchar(45) like (Spouse, Sibling, External Family and so on).
The goal here is when a new row is added (the TRIGGER) to the contact_relationships table, that we ALSO write a 2nd row to the SAME TABLE that inverts the contactIDs and keeps the relationship_type. This ensures there is also a record relationship established for the other contact from the same single entry. (ideally should be done in the app).
I'm at my whits end over what should be a stupid simple operation. I even tried this creative implementation.
I created a new _temp table
CREATE TABLE `_temp` (
`id_temp` int(11) NOT NULL AUTO_INCREMENT,
`Contact_id` int(11) DEFAULT NULL,
`Relation_id` int(11) DEFAULT NULL,
`Relationship_Type` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id_temp`)
I have two triggers on the contact_relationships table
#1
CREATE DEFINER=`root`#`localhost` TRIGGER `contact_relationships_BEFORE_INSERT` BEFORE INSERT ON `contact_relationships` FOR EACH ROW BEGIN
insert into _temp (Contact_id,Relation_id,Relationship_Type)
values(NEW.Contact_id,NEW.Relation_id,NEW.Relationship_Type);
END
#2
CREATE DEFINER=`root`#`localhost` TRIGGER `contact_relationships_AFTER_INSERT` AFTER INSERT ON `contact_relationships` FOR EACH ROW BEGIN
delete from _temp;
END
On the _temp table I have this trigger
CREATE DEFINER=`root`#`localhost` TRIGGER `_temp_AFTER_DELETE` AFTER DELETE ON `_temp` FOR EACH ROW BEGIN
#DO Sleep(2);
# Sleep commented out as it did not work and only delayed the error
insert into contact_relationships (Relation_id,Contact_id,Relationship_Type) values(OLD.Contact_id,OLD.Relation_id,OLD.Relationship_Type);
END
So my thinking here in pseudo code is like this
When a row is inserted into the contact_relationships table write the inverted row to a temp table as I can not write it to the **same table from inside the trigger**.
AFTER the triggered inserted row is complete lets delete the row in the temp table so we can create a DELETE trigger on that other table to write the desired row into the contact_relationship.
At this stage I believe the TRIGGER and TRANSACTIONS on the contact_relationships table are DONE
On the temp Table a trigger and transaction firing AFTER any contact_relationships transactions
Results are maddening and always the same albeit internal or external. I have tried creative functions and sprocs all with the same aggravating results.
Contact Relationships : Add New
Can't update table 'contact_relationships' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
Query:
insert into `Contact_Relationships` set `Contact_id`='2', `Relation_id`='3', `Relationship_Type`='Extended Family'
I'm completely brain dead on how I may accomplish this - anyone have a way to pull this off?
dsoden.
What I would do is:
Inside the trigger definition, you can get the "inserted_id" of the relationship that was inserted ( You can get it withLAST_INSERT_ID() ).
Once you have it, you can SELECT from that record into temp variables:
SELECT `Contact_id`,`Relation_id`,`Relationship_Type` INTO #cont_id, #rel_id, #rel_type
FROM contact_relationships
WHERE id = LAST_INSERT_ID()
And then do the Insert of the new relationship in the reverse order, with the same relationship type:
INSERT INTO contact_relationships (`Contact_id`,`Relation_id`,`Relationship_Type`) VALUES ( #rel_id, #cont_id, #rel_type);
If that's what you're aiming for..
Something like:
When a relationship between Anne and John as Siblings is inserted,
insert the John,Anne,Siblings relationship as well
I am using mySQL
Is there any way to set limit of table record/row? I have table X and want to set limit of total records/rows on table, for example 2rows. So no one can insert third record in table. This table should not allow to insert third record.
I do not want to use Triggers.
You can do it this the user grants, so the user cant write into this table and you can create a separate User for administration this table.
seee Manual : https://mariadb.com/kb/en/mariadb/grant/
If you dont want to use triggers, you 'll have to check the number of rows inside your application (if any).
Create an AFTER INSERT trigger on the table. - it's the only way to do it.
create trigger TableLimit
on TableName
after insert
as
declare #countTableRows int
select #countTableRows = Count(*)
from TableName
if #countTableRows > 2
begin
rollback
end
go
I tried it with the help of this query "insert into class(faculty_id) select faculty_id from faculty;" but it is inserting already existing values only. Here one column of the table is under auto-increment so I wanted to take this incremented values to another table's column in mysql workbench 6.2. I even tried setting a foreign key between the two columns but it dint work. Please can anyone help out with this issue??
This is what you want i think. an after insert trigger will fire every time something is inserted into faculty, and after the data has been inserted. You can access the values that have just been inserted with the NEW. prefix.
DELIMITER //
create trigger classInsert after insert on faculty
for each row
begin
insert into class(faculty_id) values (NEW.faculty_id);
end//
DELIMITER ;
And it will automatically add an entry into the class table every time you add a new value to faculty.
Fiddle example
I am trying to create a trigger (this is my first trigger, and question, so be gentle) that will insert new rows into two different tables.
* Edit *
Adding this in as I forgot to mention it until ypercube answered.
I am trying to avoid listing all of the column names, as in the real world usage the table this will be used on has a very large number of columns (not my design, too late to refactor).
* End Edit *
Here's what I have so far.
CREATE TABLE test_table (
id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
message VARCHAR(255)
);
CREATE TABLE test_table_copy LIKE test_table;
DELIMITER $$
CREATE TRIGGER copy_test_table_data AFTER INSERT ON test_table
FOR EACH ROW
BEGIN
INSERT INTO test_table_copy SELECT * FROM NEW;
END;$$
DELIMITER ;
Unfortunately this results in an error.
mysql> INSERT INTO test_table VALUES (1, 'This is a message');
ERROR 1146 (4502): Table 'test_db.NEW' doesn't exist
I am not quite sure what the problem is, I thought NEW referred the table data was being inserted into?
You could possibly get a list of column names in that table from information_schema views, then use them to create a prepared statement (using cursor to iterate column names) and CONCAT() function to glue together the query string. Then execute the prepared statement.
Seems very contrived even to me, and I'm not sure it would work (and if it did, how efficient it would be)
I'm new to working with triggers and am having a hard time understanding how to write a trigger to update a field in one table, when a record is inserted in another.
To elaborate, I have 2 tables: servTickets and servTicketNotes.
servTickets has several text fields for customer, contact, phone, email, problem description, status, etc...the PK in this table is an INT field called callID.
servTicketNotes has only 2 fields - again, the PK is an INT field 'callID' and there is a BLOB field called image which stores an image of a service report.
What I'm struggling to do is have a trigger update the status field in servTickets with a value of Closed when a new record is inserted into servTicketNotes.
I'm confused if this is an INSERT AFTER or BEFORE or BOTH scenario, but basically if a report is sent in (thereby creating a record in servTicketNotes, I want the trigger to seek out the record with the same callID in the servTickets table and change the value of status to 'Closed'.
This seems like it should be so simple, but I can't seem to grasp how to get started...
Thanks in advance for your help/guidance!
is it probably a POST trigger - which means:
AFTER you have committed the incoming record, you want to take further action - i.e. inserting into the other table.
if you do it PRE commit, then you would worry about some error happening on the Notes and you might end up with an incorrect update to the status.
You can do this with an AFTER INSERT trigger. Try something like this:
DELIMITER $$
DROP TRIGGER IF EXISTS tr_a_ins_servTicketNotes $$
CREATE TRIGGER pabeta.tr_a_ins_servTicketNotes AFTER INSERT ON servTicketNotes FOR EACH ROW BEGIN
update servTickets
set status = 'Closed'
where callID = NEW.callID;
END $$
DELIMITER ;