I am programming the error handling in a MySQL stored procedure using SIGNAL. I want to parametrize the error message to make it more helpful. For example
IF vMyVariable IS NULL THEN
SIGNAL SQLSTATE VALUE '45006'
SET MESSAGE_TEXT = ('Found null variable in iteration' || vId);
END IF;
I tried to use concat() and didn't work.
See https://dev.mysql.com/doc/refman/5.5/en/signal.html
and in particular the section about simple_value_specification
Arbitrary expression can not be used when assigning attributes with SET, as in:
SIGNAL SQLSTATE VALUE '45006' SET MESSAGE_TEXT = <sorry, no arbitrary expressions here>;
However, a local variable is a simple_value_specification, so the following does work:
DECLARE my_message_text VARCHAR(64);
my_message_text := <anything you want>;
SIGNAL SQLSTATE VALUE '45006' SET MESSAGE_TEXT = my_message_text;
Related
Not sure why this is returning invalid syntax:
CREATE DEFINER=`root`#`localhost` PROCEDURE `AddColor`(
IN hexvalue varchar(7),
IN notes varchar(50))
BEGIN
IF hexvalue REGEXP '^#[0-9A-F]{6}$' THEN
INSERT INTO data.colors(hexvalue,notes) VALUES (hexvalue,notes);
ELSE
SIGNAL SQLSTATE '400'
SET MESSAGE_TEXT = 'Invalid hex value specified';
END IF;
END
There doesn't seem to be any errors when writing it in.
Based on the following official documentation:
The condition_value in a SIGNAL statement indicates the error value to be returned. It can be an SQLSTATE value (a 5-character string literal) or a condition_name that refers to a named condition previously defined with DECLARE ... CONDITION (see Section 13.6.7.1, “DECLARE ... CONDITION Syntax”).
Try the following syntax and change SIGNAL SQLSTATE value to 04000:
CREATE DEFINER=`root`#`localhost` PROCEDURE `AddColor`(
IN hexvalue varchar(7),
IN notes varchar(50))
BEGIN
IF (hexvalue REGEXP '^#[0-9A-F]{6}$') THEN
INSERT INTO data.colors(`hexvalue`,`notes`) VALUES (hexvalue,notes);
ELSE
SIGNAL SQLSTATE '04000' SET MESSAGE_TEXT = 'Invalid hex value specified';
END IF;
END;
For example
Make a table such that user can enter either one of the two identity proofs:
Aadhaar card or Passport.
Formats:
Aadhaar Card: NNNN NNNN NNNN
Passport: ANNNNNN , where A is Alphabet and N is Number.
If the user enters wrong format, the input should not be accepted.
It is a better practice to validate the user input somewhere else (either in a frontend application or preferably in a business logic layer), but not in your database.
Having said that, it's still possible to validate incoming data and even apply changes to it using triggers. For example:
DELIMITER $$
CREATE TRIGGER checkInputFormat
BEFORE INSERT ON yourTable FOR EACH ROW
BEGIN
IF (NEW.card IS NULL AND NEW.passport IS NULL) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'No identity provided';
END IF;
IF (NEW.card IS NOT NULL AND NEW.card NOT REGEXP '^(\d{4} ){2}\d{4}$') THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Invalid card format';
END IF;
IF (NEW.passport IS NOT NULL AND NEW.passport NOT REGEXP '^[A-Za-z]\d{6}$') THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Invalid passport format';
END IF;
END;
$$
DELIMITER ;
This trigger will execute for each row that you try to insert in yourTable and check for the format of card and passport columns using regular expressions. If the format is invalid, an error will be thrown and the row won't be inserted.
I'm trying to manage my own errors in MySQL using a procedure and an error message table named "error_messages".
How can I manage to select a specific error message in that table?
I would like to do something like this.
DELIMITER $$
CREATE PROCEDURE throw_error_test (divisor INT)
BEGIN
SET #errorCode = '45123';
IF divisor = 0 THEN
SIGNAL SQLSTATE #errorCode
SET MESSAGE_TEXT = SELECT message
FROM error_messages
WHERE id = #errorCode;
END IF;
END;
Thanks for helping
As documented under SIGNAL Syntax:
The condition_value in a SIGNAL statement indicates the error value to be returned. It can be an SQLSTATE value (a 5-character string literal) or a condition_name that refers to a named condition previously defined with DECLARE ... CONDITION (see Section 13.6.7.1, “DECLARE ... CONDITION Syntax”).
[ deletia ]
Valid simple_value_specification designators can be specified using stored procedure or function parameters, stored program local variables declared with DECLARE, user-defined variables, system variables, or literals.
Therefore, for the MESSAGE_TEXT you could use a user variable—but my preference would be for stored program local variables; however can't specify the SQLSTATE with a variable:
CREATE PROCEDURE throw_error_test (divisor INT)
BEGIN
DECLARE _messageText VARCHAR(128);
IF divisor = 0 THEN
SELECT message
INTO _messageText
FROM error_messages
WHERE id = '45123';
SIGNAL SQLSTATE '45123' SET MESSAGE_TEXT = _messageText
END IF;
END
For the avoidance of doubt, the underscore _ prefixes are purely a convention that I adopt to avoid ambiguity—they are not a necessary part of a local variable name.
Ok so i'm working on triggers, and it tells me it(MySQL workbench 5.2) doesn't recognize this variable.
*Error Code: 1193. Unknown system variable error_msg_3*
I think it would be correct using it in a trigger, please help me
CREATE TRIGGER controlla_MaxCARDINALITA_INSERT
BEFORE INSERT ON SENTIERO__HA__TAPPA
FOR EACH ROW
BEGIN
DECLARE max_cardinalita INTEGER;
DECLARE error_msg_3 CONDITION FOR SQLSTATE '99003';
SELECT COUNT(*) into max_cardinalita
FROM SENTIERO__HA__TAPPA
WHERE IDsentiero=NEW.IDsentiero;
IF max_cardinalita>=10 THEN
SIGNAL error_msg_3;
SET error_msg_3='INSERT: Il sentiero ha già il massimo numero di tappe consentito';
END IF;
END$$
EDIT ::
I tried this, and it seems working
DECLARE msg VARCHAR(255);
set msg = concat('MyTriggerError: Trying to insert a negative value in trigger_test: ');
signal sqlstate '45000' set message_text = msg;
According to MySQL docs, the error #1193 occurs when you use wrong code for SQLSTATE.
Message: Unknown system variable %s
And, as you can see on the same page, the SQLSTATE 99003 is not defined.
I am trying to setup a trigger so an insert does not occur if a condition is not met.
I thought the below was the way to do it but i am not sure
I am getting an error
/* SQL Error (1407): Bad SQLSTATE: '45000 ' */
Can anyone let me know why I am getting this error and the best way for me to prevent an insert if the condition is not met in mysql.
DELIMITER $$
SHOW WARNINGS$$
USE `warrington_central`$$
CREATE TRIGGER before_insert_image_comment_section_check
BEFORE INSERT ON image_comment FOR EACH ROW
BEGIN
DECLARE error_msg varchar(255);
IF New.section != (SELECT id from section where section = "image")
THEN SET error_msg = "Cannot insert a comment into this section as it is the wrong section type";
SIGNAL SQLSTATE '45000 'SET MESSAGE_TEXT = error_msg;
END IF;
END
$$
SHOW WARNINGS$$
SQLSTATE is required to be a a 5 character string unless previously declared using DECLARE ... CONDITION;
SIGNAL SQLSTATE '45000 'SET MESSAGE_TEXT = error_msg;
You're trying to set SQLSTATE to '45000 ' (note the space) which is 6 characters long. Fix the spacing and you should not see the message again (it is also reflected in your error message, but the space is a bit hard to see)