I have a table called COURSE with these columns:
CourseId int
CourseName varchar
DateofStart Date
I would like to create a trigger which ensures that courses cannot be run during August.
Check the examples given in this site for writing the trigger
https://docs.oracle.com/cd/B19306_01/appdev.102/b14251/adfns_triggers.htm#i1025109
step 1: Since you need to check that courses cannot run during the august, you would be requiring a BEFORE INSERT trigger type.(Check the syntax in the link)
Step 2: Write the logic in Trigger body which will check the date that is being entered in the table
Step 3: If the DateofStart is in august raise an exception or process accordingly
Do try and share the code snippet.
Try this SQL code (for SQL Server)
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TRIGGER Tr_Course
ON Course
INSTEAD OF UPDATE
AS
BEGIN
SET NOCOUNT ON;
IF TRIGGER_NESTLEVEL() > 1
RETURN
UPDATE Course
SET dateOfStart = I.dateOfStart
FROM Course AS C
JOIN INSERTED I ON C.courseID = I.courseID
WHERE MONTH(I.dateOfStart) <> 8
END
GO
create trigger check_month
on COURSE
for Insert
as
declare #Date nvarchar(10)
declare #month int
select #Date=i.DateofStart from inserted i;
set #month= (select DATEPART(MONTH,#Date))
if(#month=8)
begin
Rollback
end
else
begin
commit
end
Related
I have 3 tables
tbl_payments(pay_id,date,amount,description,-------)
tbl_pay_trans(pay_id,trans_id)
tbl_transactions(trans_id,trans_date,trans_amount,trans_description,-----)
'tbl_transaction' has the same data from the 'tbl_payments' along with some other values. To maintain the relationship between the two tables I use 'tbl_pay_trans'. What I want to do is, when an update done on tbl_payments(amount,description) the same changes need to do in tbl_transactions(trans_amount,trans_description). I wrote a trigger to do that, but it dose not update the tbl_transaction table values as it supposed to.
My trigger is
DELIMITER $$
CREATE TRIGGER update_trans
AFTER UPDATE on tbl_payments
FOR EACH ROW
BEGIN
DECLARE new_amount VARCHAR(50);
DECLARE new_description TEXT;
DECLARE new_pay_id,new_trans_id INT;
SET new_pay_id = OLD.pay_id;
SET new_amount = OLD.amount;
SET new_description = OLD.description;
SELECT trans_id INTO new_trans_id FROM tbl_pay_trans WHERE pay_id = new_pay_id;
UPDATE tbl_transactions SET
trans_amount = new_amount,
trans_description = new_description
WHERE trans_id = new_trans_id;
END$$
DELIMITER ;
Please someone help me to figure out what I did wrong.
It's not updating because you are using OLD on the amount and description columns where you need to use NEW i.e.
SET new_amount = NEW.amount;
SET new_description = NEW.description;
OLD refers to the column value before the update occurred in tbl_payments. See the manual.
I did a trigger in mysql to shoot alerts always an input value was less than the set value. But now I need it is done in SQL SERVER.
I would be grateful if someone could help me transform mysql trigger to a SQL Server trigger.
Thanks to all at once.
My trigger is:
DELIMITER $$
create TRIGGER alert
AFTER INSERT ON records
FOR EACH ROW
begin
Set #comp=0;
Set #tempmax=0;
Set #tempmin=0;
select lim_inf_temp into #tempmin from sensores where idSensor=NEW.idSensor;
Set #maxidAlarme=0;
if (CAST(NEW.Temperatura AS UNSIGNED)<#tempmin) then
SELECT MAX(idAlarme) into #maxidAlarme FROM alarmes;
SET #maxidAlarme=#maxidAlarme+1;
INSERT INTO alarmes(idAlarme,descricao_alarme, idRegisto) VALUES (#maxidAlarme,"inserted below the normal temperature",New.idRegisto);
INSERT INTO sensores_tem_alarmes(idSensor,idAlarme,dataAlarme) VALUES (NEW.idSensor,#maxidAlarme,NOW());
set #comp=+1;
end if;
set #id_sensores_em_alerta=1;
SELECT MAX(id_sensores_em_alerta) into #id_sensores_em_alerta FROM sensores_em_alerta;
INSERT INTO sensores_em_alerta(id_sensores_em_alerta, idSensor, idAlarme, data_registo, numerosensoresdisparados) VALUES (id_sensores_em_alerta,NEW.idSensor, #maxidAlarme, NOW(), #comp);
end $$;
DELIMITER ;
I've tried to make the trigger in SQL Server, but as the script is different and I'm getting many difficulties to do the right way.
My attempt that was not going at all well:
CREATE TRIGGER Alert ON registos AFTER INSERT AS
BEGIN
DECLARE #comp decimal= 0
DECLARE #tempmax decimal= 0
DECLARE #tempmin decimal= 0
DECLARE #current_max_idAlarme int = (SELECT MAX(IdAlarme) FROM alarmes)
-- Insert into alarmes from the inserted rows if temperature less than tempmin
INSERT alarmes (IdAlarme, descricao_alarme, idRegisto)
SELECT
ROW_NUMBER() OVER (ORDER BY i.idRegisto) + #current_max_idAlarme,
'temp Error',
i.idRegisto
FROM
inserted AS i
WHERE
i.Temperatura < #tempmin
END
But dont do anything.
Dont create data on table alarmes :S
Does anyone could help me please. I would be eternally grateful.
Many Greetings and thank you all.
First of all, MSSQL doesn't have the option FOR EACH ROW, so it treats multiple inserted rows at once as a set. You will therefore have to insert the values into a table variable.
Unfortunately I do not know much MySQL actually, but I believe this is a starting point?
CREATE TRIGGER ALERT
ON records
AFTER INSERT
AS
BEGIN
DECLARE #comp INT;
DECLARE #tempmax INT;
DECLARE TABLE #tempmin (tempmin INT);
INSERT INTO #tempmin
SELECT s.lim_inf_temp FROM sensores s WHERE s.idSensor IN (inserted.idSensor);
--rest of the code
I'm going to post this code against my better judgement - redesign the tables is better than this hack.
This uses a ROW_number() to virtualise a surrogate identity key for the alarmes table. This is a 'bad plan' (tm).
Also the answer is partial - it doesn't do everything your question asked for -- I hope it gets your further along the road. Use it as a guide for how to interact with the virtual INSERTED table. Good luck
CREATE TRIGGER Alert ON records AFTER INSERT AS
BEGIN
DECLARE #comp INT = 0
DECLARE #tempmax INT = 0
DECLARE #tempmin INT = 0
-- get the max current id.
-- note that this is EXTREMELY unsafe as if two pieces of code are executing
-- at the same time then you *will* end up with key conflicts.
-- you could use SERIALIZABLE.... but better would be to redisn the schema
DECLARE #current_max_idAlarme = (SELECT MAX(IdAlarme) FROM alarmes)
-- Insert into alarmes from the inserted rows if temperature less than tempmin
INSERT alarmes (IdAlarme, descricao_alarme, idRegisto)
SELECT
ROW_NUMBER() OVER (ORDER BY i.idRegisto) + #current_max_idAlarme,
'temp Error',
i.idRegisto
FROM
inserted AS i
WHERE
i.Temperatura < #tempmin
END
I have created a mysql trigger to update on insert a value from another table:
DROP TRIGGER IF EXISTS `CourseCode`//
CREATE TRIGGER `CourseCode` BEFORE INSERT ON `race`
FOR EACH ROW BEGIN
SET NEW.Course_Code = (
SELECT
course_code
from
tb_course
where
tb_course.course_name = NEW.course_name
)
END
//
This works perfectly. It returns the 4 character code for the course_name based on the tb_course table.
What I'm trying to do is the exact same thing in another table, I copy and paste the trigger and rename the trigger and the table (field names and types are also identical) it but it won't work:
DROP TRIGGER IF EXISTS `CourseCode2`//
CREATE TRIGGER `CourseCode2` BEFORE INSERT ON `fields`
FOR EACH ROW
BEGIN
SET NEW.Course_Code = (
SELECT
course_code
from
tb_course
where
tb_course.course_name = NEW.course_name
)
END
//
However this results in null values. I've tried replacing New.Course_name with a string (i.e. tb_course.course_name="String") and that updates that static value fine so the trigger appears to be working but either it isn't matching the select statement in this table for or it's not setting the Course_Code field...
Is there any sort of debugging you can suggest to figure this out? It's driving me nuts and I don't know what to do to diagnose the problem.
Cheers
I have no idea what is wrong with the second trigger.
However, the 'debugging' part i can maybe help with.
A search of the 'net' will return various software (paid for) that will allow single step debugging. Rather than pay for stuff, all i want is 'print' statements from inside stored function procedures and triggers.
a quick search lead me to someone who has done all the work already.
Debugging Stored Procedures in MySql
I have just set it up in MySql and tried it and it works fine.
Here is some sample code, based on your trigger and the output i got.
DELIMITER $$
USE `testmysql`$$
DROP TRIGGER /*!50032 IF EXISTS */ `CourseCode`$$
CREATE
/*!50017 DEFINER = 'test'#'localhost' */
TRIGGER `CourseCode` BEFORE INSERT ON `race`
FOR EACH ROW BEGIN
DECLARE v_course_code INT;
DECLARE v_course_title VARCHAR(255);
CALL procLog("line 12: Entering CourseCode");
SELECT
course_code, course_title
INTO
v_course_code, v_course_title
FROM
tb_course
WHERE
tb_course.course_name = NEW.course_name;
SET NEW.course_code = v_course_code;
CALL procLog(CONCAT("line_22: ", v_course_title, " code: ", NEW.course_code));
CALL procLog("line 24: Exiting CourseCode");
END;
$$
DELIMITER ;
Query:
CALL setupProcLog();
INSERT INTO `race` (course_name, race_info)
VALUES ('learn_it_02', 'this is another test');
CALL cleanup('query end');
procLog output:
entrytime connection_id msg
2014-02-23 12:32:21 5 line 12: Entering CourseCode
2014-02-23 12:32:21 5 line_22: Learn It Course 02 code: 2
2014-02-23 12:32:21 5 line 24: Exiting CourseCode
2014-02-23 12:32:21 5 cleanup() query end
Ok, a little clumsy maybe but it will help with debugging 'stored' programs.
I will be using it from now on.
I'm fairly new to SQL in general and even more so to MySQL and I've hit a stumbling block. I'm attempting to use a procedure to copy the value of one field to another if the original field is not null, this procedure is then called by triggers whenever the table is updated or has a new row inserted into it. Here is what I have so far:
-- WORK_NOTES_PROCEDURE - This copies the contents of the estimate notes to the work order notes if the original estimate had any notes with it.
DROP PROCEDURE IF EXISTS 'WORK_NOTES_PROCEDURE';
DELIMITER $$
CREATE PROCEDURE WORK_NOTES_PROCEDURE()
BEGIN
DECLARE var_temp VARCHAR(50);
SET var_temp := (SELECT ESTIMATE_NOTES FROM ESTIMATES WHERE ESTIMATES.ESTIMATE_NUMBER = WORK_ORDERS.ESTIMATE_NUMBER);
IF var_temp IS NOT NULL THEN
UPDATE WORK_ORDERS SET WORK_ORDER_NOTES = var_temp WHERE WORK_ORDERS.ESTIMATE NUMBER = ESTIMATES.ESTIMATE_NUMBER;
END IF;
END$$
DELIMITER ;
Absolutely any help would be appreciated, the error I'm getting is a syntax error for the line where I'm assigning a value to var_temp.
try,
SET var_temp = (SELECT ESTIMATE_NOTES
FROM ESTIMATES INNER JOIN WORK_ORDERS
ON ESTIMATES.ESTIMATE_NUMBER = WORK_ORDERS.ESTIMATE_NUMBER
LIMIT 1);
I want to generate PK through trigger as it is custom PK.
It is like depending on the member type field, I want to generate member id which is PK.
e.g. if new record's member type is DGIA, then member id will be DGIA1, DGIA2, DGIA3 ...and so on... if member type is DGIL, then member id will be DGIL1, DGIL2, DGIL3 ...and so on...
So, how to write trigger for the same... I have tried as following but it is working for 1st record only.
ALTER TRIGGER [dbo].[next_member_id] ON [dbo].[DAD_MEMBERSHIP] AFTER INSERT
AS
BEGIN
DECLARE #COUNT INT
SET #COUNT=0;
SELECT #COUNT=ISNULL(MAX(CAST(SUBSTRING(DAD_MEMBERSHIP.MEMBER_ID,5,15) AS INT)),0)+1 FROM DAD_MEMBERSHIP where DAD_MEMBERSHIP.MEMBER_TYPE = DAD_MEMBERSHIP.MEMBER_TYPE
update DAD_MEMBERSHIP set DAD_MEMBERSHIP.MEMBER_ID = DAD_MEMBERSHIP.MEMBER_TYPE + CONVERT(varchar,#COUNT)
from DAD_MEMBERSHIP inner join inserted on DAD_MEMBERSHIP.MEMBER_TYPE = inserted.MEMBER_TYPE
END
Triggers operate by batch of records, you cannot assign to a scalar variable and expect it to work for more than one record. You need to rethink your whole process into a set-based process.
I solved the problem using following trigger
ALTER TRIGGER [dbo].[next_member_id]
ON [dbo].[DAD_MEMBERSHIP]
AFTER INSERT
AS
BEGIN
DECLARE #COUNT INT
SET #COUNT=0;
DECLARE #STR VARCHAR(5)
SET #STR=''
select #STR=i.MEMBER_TYPE from inserted i;
SELECT #COUNT=ISNULL(MAX(CAST(SUBSTRING(DAD_MEMBERSHIP.MEMBER_ID,5,15) AS INT)),0)+1
from DAD_MEMBERSHIP where MEMBER_TYPE=#STR
update DAD_MEMBERSHIP set DAD_MEMBERSHIP.MEMBER_ID = #STR + CONVERT(varchar,#COUNT)
from DAD_MEMBERSHIP inner join inserted i on i.MEMBER_TYPE=DAD_MEMBERSHIP.MEMBER_TYPE where DAD_MEMBERSHIP.MEMBER_ID is null
END