CREATE PROCEDURE `go`()
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN DECLARE d_z CONDITION FOR SQLSTATE '35241';
SELECT COUNT(*)as #a from _time
IF #a>0 THEN
SIGNAL d_z SET MESSAGE_TEXT='errrrrrrrrrrrr';
END IF;
END;
error:SQL Error (1064): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '#a from _time
IF #a>0 THEN SIGNAL d_z SET MESSAGE_TEXT='errrrrrrrrrr' at line 9
The problem is with the select statement "#a" is alias name which cant be used further queries.
You can use peterm query "into" instead of as
Hope this helps
Happy Coding
You has some syntax issues. Following works for me:
DELIMITER //
CREATE PROCEDURE `go`()
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN
DECLARE d_z CONDITION FOR SQLSTATE '35241';
select count(*) INTO #a from _time;
IF #a>0 THEN
SIGNAL d_z SET MESSAGE_TEXT='errrrrrrrrrrrr';
END IF;
END
//
Important is to:
Use into #variable syntax for selecting a value into a var
Use DELIMITER for termination of multiline procedure body
Your immediate error is caused by the malformed SELECT statement. You have to a proper SELECT INTO syntax
Change
SELECT COUNT(*)as #a from _time
to
SELECT COUNT(*) INTO #a FROM _time
^^^^
Now there are several other issues with your code:
There is no need to use a user(session) variable, you could've used local variable instead
You don't want to get total number of all rows just to tell whether you have rows or not in your table. If you do you'll pay performance penalty (if of course you're not using MyISAM). You can leverage NOT EXISTS() for that or LIMIT 1 clause.
That being said a streamlined version of your procedure might look like
DELIMITER $$
CREATE PROCEDURE `go`()
BEGIN
DECLARE d_z CONDITION FOR SQLSTATE '35241';
IF NOT EXISTS(SELECT * FROM _time) THEN
SIGNAL d_z SET MESSAGE_TEXT='errrrrrrrrrrrr';
END IF;
END$$
DELIMITER ;
Here is SQLFiddle demo
Let's give it a try
mysql> CREATE TABLE _time (`id` int);
Query OK, 0 rows affected (0.03 sec)
mysql> DELIMITER $$
mysql> CREATE PROCEDURE `go`()
-> BEGIN
-> DECLARE d_z CONDITION FOR SQLSTATE '35241';
-> IF NOT EXISTS(SELECT * FROM _time) THEN
-> SIGNAL d_z SET MESSAGE_TEXT='errrrrrrrrrrrr';
-> END IF;
-> END$$
Query OK, 0 rows affected (0.02 sec)
mysql> DELIMITER ;
mysql> CALL go();
ERROR 1644 (35241): errrrrrrrrrrrr
Related
If I have a trigger before the update on a table, how can I throw an error that prevents the update on that table?
As of MySQL 5.5, you can use the SIGNAL syntax to throw an exception:
signal sqlstate '45000' set message_text = 'My Error Message';
State 45000 is a generic state representing "unhandled user-defined exception".
Here is a more complete example of the approach:
delimiter //
use test//
create table trigger_test
(
id int not null
)//
drop trigger if exists trg_trigger_test_ins //
create trigger trg_trigger_test_ins before insert on trigger_test
for each row
begin
declare msg varchar(128);
if new.id < 0 then
set msg = concat('MyTriggerError: Trying to insert a negative value in trigger_test: ', cast(new.id as char));
signal sqlstate '45000' set message_text = msg;
end if;
end
//
delimiter ;
-- run the following as seperate statements:
insert into trigger_test values (1), (-1), (2); -- everything fails as one row is bad
select * from trigger_test;
insert into trigger_test values (1); -- succeeds as expected
insert into trigger_test values (-1); -- fails as expected
select * from trigger_test;
Here is one hack that may work. It isn't clean, but it looks like it might work:
Essentially, you just try to update a column that doesn't exist.
Unfortunately, the answer provided by #RuiDC does not work in MySQL versions prior to 5.5 because there is no implementation of SIGNAL for stored procedures.
The solution I've found is to simulate a signal throwing a table_name doesn't exist error, pushing a customized error message into the table_name.
The hack could be implemented using triggers or using a stored procedure. I describe both options below following the example used by #RuiDC.
Using triggers
DELIMITER $$
-- before inserting new id
DROP TRIGGER IF EXISTS before_insert_id$$
CREATE TRIGGER before_insert_id
BEFORE INSERT ON test FOR EACH ROW
BEGIN
-- condition to check
IF NEW.id < 0 THEN
-- hack to solve absence of SIGNAL/prepared statements in triggers
UPDATE `Error: invalid_id_test` SET x=1;
END IF;
END$$
DELIMITER ;
Using a stored procedure
Stored procedures allows you to use dynamic sql, which makes possible the encapsulation of the error generation functionality in one procedure. The counterpoint is that we should control the applications insert/update methods, so they use only our stored procedure (not granting direct privileges to INSERT/UPDATE).
DELIMITER $$
-- my_signal procedure
CREATE PROCEDURE `my_signal`(in_errortext VARCHAR(255))
BEGIN
SET #sql=CONCAT('UPDATE `', in_errortext, '` SET x=1');
PREPARE my_signal_stmt FROM #sql;
EXECUTE my_signal_stmt;
DEALLOCATE PREPARE my_signal_stmt;
END$$
CREATE PROCEDURE insert_test(p_id INT)
BEGIN
IF NEW.id < 0 THEN
CALL my_signal('Error: invalid_id_test; Id must be a positive integer');
ELSE
INSERT INTO test (id) VALUES (p_id);
END IF;
END$$
DELIMITER ;
The following procedure is (on mysql5) a way to throw custom errors , and log them at the same time:
create table mysql_error_generator(error_field varchar(64) unique) engine INNODB;
DELIMITER $$
CREATE PROCEDURE throwCustomError(IN errorText VARCHAR(44))
BEGIN
DECLARE errorWithDate varchar(64);
select concat("[",DATE_FORMAT(now(),"%Y%m%d %T"),"] ", errorText) into errorWithDate;
INSERT IGNORE INTO mysql_error_generator(error_field) VALUES (errorWithDate);
INSERT INTO mysql_error_generator(error_field) VALUES (errorWithDate);
END;
$$
DELIMITER ;
call throwCustomError("Custom error message with log support.");
CREATE TRIGGER sample_trigger_msg
BEFORE INSERT
FOR EACH ROW
BEGIN
IF(NEW.important_value) < (1*2) THEN
DECLARE dummy INT;
SELECT
Enter your Message Here!!!
INTO dummy
FROM mytable
WHERE mytable.id=new.id
END IF;
END;
Another (hack) method (if you are not on 5.5+ for some reason) that you can use:
If you have a required field, then within a trigger set the required field to an invalid value such as NULL. This will work for both INSERT and UPDATE. Do note that if NULL is a valid value for the required field (for some crazy reason) then this approach will not work.
BEGIN
-- Force one of the following to be assigned otherwise set required field to null which will throw an error
IF (NEW.`nullable_field_1` IS NULL AND NEW.`nullable_field_2` IS NULL) THEN
SET NEW.`required_id_field`=NULL;
END IF;
END
If you are on 5.5+ then you can use the signal state as described in other answers:
BEGIN
-- Force one of the following to be assigned otherwise use signal sqlstate to throw a unique error
IF (NEW.`nullable_field_1` IS NULL AND NEW.`nullable_field_2` IS NULL) THEN
SIGNAL SQLSTATE '45000' set message_text='A unique identifier for nullable_field_1 OR nullable_field_2 is required!';
END IF;
END
DELIMITER ##
DROP TRIGGER IF EXISTS trigger_name ##
CREATE TRIGGER trigger_name
BEFORE UPDATE ON table_name
FOR EACH ROW
BEGIN
--the condition of error is:
--if NEW update value of the attribute age = 1 and OLD value was 0
--key word OLD and NEW let you distinguish between the old and new value of an attribute
IF (NEW.state = 1 AND OLD.state = 0) THEN
signal sqlstate '-20000' set message_text = 'hey it's an error!';
END IF;
END ##
DELIMITER ;
Hi I have been asked to create a Trigger that increments a variable #count on each Insertion.
I have written this query
DELIMITER//
BEGIN
DECLARE #count int[DEFAULT NULL]
CREATE TRIGGER trig
AFTER INSERT ON students
FOR EACH ROW SET #count = #count + 1;
END//
Now at this point I get the error 1064 (42000): You have an error in your SQL syntax and so on....
In my opinion maybe there is some problem in the declare statement but that is the prescribed syntax on net.
I am using MySQL 5.6 Command Line
The syntax is not correct and its not mysql way of declare, it should be as below and you do not need to declare the session variables like you did
delimiter //
CREATE TRIGGER trig AFTER INSERT ON student
for each row
begin
set #count = #count + 1 ;
end;//
delimiter ;
I am trying to write trigger in Mysql (5.1), but getting following error, please help.
The error is:
SQL Error (1064): You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right
syntax to use near '' at line 5.
Purpose for writing trigger:
I am writing application where I am assigning users, and I want to store unassigned usercount to field cluster_count in IX_branchdetails table.After updating the base table.
trigger:
DELIMITER $$
CREATE TRIGGER upd_trg AFTER
UPDATE ON DBNAME.BASETABLE
FOR EACH ROW
BEGIN
DECLARE m_branchcode INTEGER;
DECLARE cnt INTEGER;
DECLARE cursor_branch CURSOR FOR
SELECT DISTINCT branchcode
FROM ix_branchdetails;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
open cursor_branch;
my_loop: loop
set done = false;
fetch cursor_branch into m_branchcode;
if done then
leave my_loop;
end if;
select count(1) into cnt from (select count(1) from BASETABLE Where IX_BRANCHCODE = m_branchcode) as temp;
update DBANAME.ix_branchdetails set DBANAME.ix_branchdetails.cluster_count = cnt where DBANAME.ix_branchdetails.BRANCHCODE = m_branchcode;
end loop my_loop;
close cursor_branch;
END $$
DELIMITER ;
I don't see a declare for the done variable:
DECLARE done TINYINT DEFAULT FALSE;
The semicolon (;) is the default delimiter for MySQL statements. To get a procedure/function/trigger defined, we normally see the statement delimiter changed to a string that doesn't appear in the statement:
DELIMITER $$
CREATE PROCEDURE ...
END$$
DELIMITER ;
If the delimiter is not changed from the semicolon, then when MySQL encounters the first semicolon in your procedure/function/trigger, it sees that as the end of the statement, which is not what you want. You want MySQL to see the entire block of code as a single statement.
Hi
Is there any error in this TRIGGER Statement.When ever i try to run this in phpAdmin its giving error saying "#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near "SELECT Count(*) into SIM_CCode_Count".I cant get what's wrong in this..please help me
This is my trigger statement
CREATE TRIGGER Is_CountryCode_There After INSERT on mr_details FOR EACH ROW
BEGIN
DECLARE SIM_CCode_Count INTEGER;
DECLARE NET_CCode_Count INTEGER;
SELECT Count(*) into SIM_CCode_Count FROM Country_Main where CountryCode=NEW.SimCntISO;
IF SIM_CCode_Count=0 THEN
INSERT INTO Country_Main(CountryCode,CountryName) Values(NEW.SIMCntISO,"Unknown");
END IF
If NEW.SimCntISO<>NEW.NetCntISO then
SELECT Count(*) into NET_CCode_Count FROM Country_Main
where CountryCode=NEW.NetCntISO
IF NET_CCode_Count=0 THEN
INSERT INTO Country_Main(CountryCode,CountryName) Values(NEW.NETCntISO,"Unknown");
END IF
END IF
END
Without proper explanation about your requirement and about tables and what you are expecting this trigger to do,its very difficult to say if any issues there in your trigger..
But as far as i can see there is some minor correction need to be done..
Try this Code and let know in detail your requirements..
CREATE TRIGGER Is_CountryCode_There After INSERT on mr_details FOR EACH ROW
BEGIN
DECLARE SIM_CCode_Count INTEGER;
DECLARE NET_CCode_Count INTEGER;
SELECT Count(*) into SIM_CCode_Count FROM Country_Main where CountryCode=NEW.SimCntISO;
IF SIM_CCode_Count=0 THEN
INSERT INTO Country_Main(CountryCode,CountryName) Values(NEW.SIMCntISO,"Unknown");
END IF;
If (NEW.SimCntISO<>NEW.NetCntISO) then
SELECT Count(*) into NET_CCode_Count FROM Country_Main
where CountryCode=NEW.NetCntISO;
IF NET_CCode_Count=0 THEN
INSERT INTO Country_Main(CountryCode,CountryName) Values(NEW.NETCntISO,"Unknown");
END IF;
End IF;
END;
You have to declare a mysql-statement delimiter before the trigger statement:
DELIMITER |
CREATE TRIGGER ...
(your code)
END|
DELIMITER ;
Otherwise MySQL interprets your ; in this statement as statement commit and executes the code immidiately. With the delimiter changed to a different character you can use the semicolon inside the trigger declaration safely.
See here: http://dev.mysql.com/doc/refman/5.0/en/create-procedure.html
If I have a trigger before the update on a table, how can I throw an error that prevents the update on that table?
As of MySQL 5.5, you can use the SIGNAL syntax to throw an exception:
signal sqlstate '45000' set message_text = 'My Error Message';
State 45000 is a generic state representing "unhandled user-defined exception".
Here is a more complete example of the approach:
delimiter //
use test//
create table trigger_test
(
id int not null
)//
drop trigger if exists trg_trigger_test_ins //
create trigger trg_trigger_test_ins before insert on trigger_test
for each row
begin
declare msg varchar(128);
if new.id < 0 then
set msg = concat('MyTriggerError: Trying to insert a negative value in trigger_test: ', cast(new.id as char));
signal sqlstate '45000' set message_text = msg;
end if;
end
//
delimiter ;
-- run the following as seperate statements:
insert into trigger_test values (1), (-1), (2); -- everything fails as one row is bad
select * from trigger_test;
insert into trigger_test values (1); -- succeeds as expected
insert into trigger_test values (-1); -- fails as expected
select * from trigger_test;
Here is one hack that may work. It isn't clean, but it looks like it might work:
Essentially, you just try to update a column that doesn't exist.
Unfortunately, the answer provided by #RuiDC does not work in MySQL versions prior to 5.5 because there is no implementation of SIGNAL for stored procedures.
The solution I've found is to simulate a signal throwing a table_name doesn't exist error, pushing a customized error message into the table_name.
The hack could be implemented using triggers or using a stored procedure. I describe both options below following the example used by #RuiDC.
Using triggers
DELIMITER $$
-- before inserting new id
DROP TRIGGER IF EXISTS before_insert_id$$
CREATE TRIGGER before_insert_id
BEFORE INSERT ON test FOR EACH ROW
BEGIN
-- condition to check
IF NEW.id < 0 THEN
-- hack to solve absence of SIGNAL/prepared statements in triggers
UPDATE `Error: invalid_id_test` SET x=1;
END IF;
END$$
DELIMITER ;
Using a stored procedure
Stored procedures allows you to use dynamic sql, which makes possible the encapsulation of the error generation functionality in one procedure. The counterpoint is that we should control the applications insert/update methods, so they use only our stored procedure (not granting direct privileges to INSERT/UPDATE).
DELIMITER $$
-- my_signal procedure
CREATE PROCEDURE `my_signal`(in_errortext VARCHAR(255))
BEGIN
SET #sql=CONCAT('UPDATE `', in_errortext, '` SET x=1');
PREPARE my_signal_stmt FROM #sql;
EXECUTE my_signal_stmt;
DEALLOCATE PREPARE my_signal_stmt;
END$$
CREATE PROCEDURE insert_test(p_id INT)
BEGIN
IF NEW.id < 0 THEN
CALL my_signal('Error: invalid_id_test; Id must be a positive integer');
ELSE
INSERT INTO test (id) VALUES (p_id);
END IF;
END$$
DELIMITER ;
The following procedure is (on mysql5) a way to throw custom errors , and log them at the same time:
create table mysql_error_generator(error_field varchar(64) unique) engine INNODB;
DELIMITER $$
CREATE PROCEDURE throwCustomError(IN errorText VARCHAR(44))
BEGIN
DECLARE errorWithDate varchar(64);
select concat("[",DATE_FORMAT(now(),"%Y%m%d %T"),"] ", errorText) into errorWithDate;
INSERT IGNORE INTO mysql_error_generator(error_field) VALUES (errorWithDate);
INSERT INTO mysql_error_generator(error_field) VALUES (errorWithDate);
END;
$$
DELIMITER ;
call throwCustomError("Custom error message with log support.");
CREATE TRIGGER sample_trigger_msg
BEFORE INSERT
FOR EACH ROW
BEGIN
IF(NEW.important_value) < (1*2) THEN
DECLARE dummy INT;
SELECT
Enter your Message Here!!!
INTO dummy
FROM mytable
WHERE mytable.id=new.id
END IF;
END;
Another (hack) method (if you are not on 5.5+ for some reason) that you can use:
If you have a required field, then within a trigger set the required field to an invalid value such as NULL. This will work for both INSERT and UPDATE. Do note that if NULL is a valid value for the required field (for some crazy reason) then this approach will not work.
BEGIN
-- Force one of the following to be assigned otherwise set required field to null which will throw an error
IF (NEW.`nullable_field_1` IS NULL AND NEW.`nullable_field_2` IS NULL) THEN
SET NEW.`required_id_field`=NULL;
END IF;
END
If you are on 5.5+ then you can use the signal state as described in other answers:
BEGIN
-- Force one of the following to be assigned otherwise use signal sqlstate to throw a unique error
IF (NEW.`nullable_field_1` IS NULL AND NEW.`nullable_field_2` IS NULL) THEN
SIGNAL SQLSTATE '45000' set message_text='A unique identifier for nullable_field_1 OR nullable_field_2 is required!';
END IF;
END
DELIMITER ##
DROP TRIGGER IF EXISTS trigger_name ##
CREATE TRIGGER trigger_name
BEFORE UPDATE ON table_name
FOR EACH ROW
BEGIN
--the condition of error is:
--if NEW update value of the attribute age = 1 and OLD value was 0
--key word OLD and NEW let you distinguish between the old and new value of an attribute
IF (NEW.state = 1 AND OLD.state = 0) THEN
signal sqlstate '-20000' set message_text = 'hey it's an error!';
END IF;
END ##
DELIMITER ;