Error Handling In Mysql Trigger
Contents |
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about
Mysql Trigger Throw Error
hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges error handling in mysql procedure Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other.
Exception Handling In Mysql
Join them; it only takes a minute: Sign up TRIGGERs that cause INSERTs to fail? Possible? up vote 13 down vote favorite 8 In cleaning up this answer I learnt a bit about TRIGGERs and stored procedures in MySQL, mysql signal example but was stunned that, while BEFORE INSERT and BEFORE UPDATE triggers could modify data, they seemingly couldn't cause the insert/update to fail (ie. validation). In this particular case I was able to get this to work by manipulating the data in such a way as to cause a primary key duplicate, which in this particular case made sense, but doesn't necessarily make sense in a general sense. Is this sort of functionality possible in MySQL? In any other mysql stored procedure error handling RDBMS (my experience is limited to MySQL sadly)? Perhaps a THROW EXCEPTION style syntax? mysql triggers rdbms share|improve this question edited Oct 23 '08 at 16:07 Mark Brady asked Oct 23 '08 at 13:46 Matthew Scharley 61.3k39151197 1 from MySQL 5.5, possibly earlier, you can use signals, [see my answer here][1] [1]: stackoverflow.com/questions/24/throw-error-in-mysql-trigger/… –RuiDC Aug 25 '11 at 11:18 add a comment| 6 Answers 6 active oldest votes up vote 19 down vote accepted From this blog post MySQL Triggers: How do you abort an INSERT, UPDATE or DELETE with a trigger? On EfNet’s #mysql someone asked: How do I make a trigger abort the operation if my business rule fails? In MySQL 5.0 and 5.1 you need to resort to some trickery to make a trigger fail and deliver a meaningful error message. The MySQL Stored Procedure FAQ says this about error handling: SP 11. Do SPs have a “raise” statement to “raise application errors”? Sorry, not at present. The SQL standard SIGNAL and RESIGNAL statements are on the TODO. Perhaps MySQL 5.2 will include SIGNAL statement which will make this hack stolen straight from MySQL Stored Procedure Programming obsolete. What is the hack? You’re going to force MySQL to attempt to use a column that does not exist. Ugly? Yes. Does it work? Sure. CREATE TRIGGER mytabletriggerexample BEFORE INSERT FOR EACH ROW BEGIN IF(NEW.important_value) < (fancy * dancy
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business
Mysql Stored Procedure Raise Error
Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation mysql raise error in trigger Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like
Mysql Resignal
you, helping each other. Join them; it only takes a minute: Sign up How to catch any exception in triggers and store procedures for mysql? up vote 1 down vote favorite 1 I have been trying to http://stackoverflow.com/questions/229765/triggers-that-cause-inserts-to-fail-possible catch mysql exception especially for triggers and store procedures.How can we catch the exception from mysql side?. I still not found any solution. your help would be appreciate. Thanks Hitesh mysql stored-procedures triggers share|improve this question asked Aug 2 '11 at 7:12 Hitesh 7381511 add a comment| 2 Answers 2 active oldest votes up vote 2 down vote Check out the syntax for DECLARE HANDLER http://dev.mysql.com/doc/refman/5.1/en/declare-handler.html Also, if you're trying to debug a SP, this might http://stackoverflow.com/questions/6908453/how-to-catch-any-exception-in-triggers-and-store-procedures-for-mysql be helpful for you: http://www.bluegecko.net/mysql/debugging-stored-procedures/ share|improve this answer answered Aug 2 '11 at 7:20 user470714 2,1731630 add a comment| up vote 1 down vote Because this comes up in the top of my search for MySQL error handling in triggers, I thought I'd share my solution for MySQL 5.5+ My original post: http://stackoverflow.com/a/26115231/1733365 Duplicated below... Because this article comes up towards the top when I search for error handling in MySQL triggers, I thought I'd share some knowledge. If there is an error, you can force MySQL to use a SIGNAL, but if you don't specify it as a class as SQLEXCEPTION, then nothing will happen, as not all SQLSTATEs are considered bad, and even then you'd have to make sure to RESIGNAL if you have any nested BEGIN/END blocks. Alternatively, and probably simpler still, within your trigger, declare an exit handler and resignal the exception. CREATE TRIGGER `my_table_AINS` AFTER INSERT ON `my_table` FOR EACH ROW BEGIN DECLARE EXIT HANDLER FOR SQLEXCEPTION RESIGNAL; DECLARE EXIT HANDLER FOR SQLWARNING RESIGNAL; DECLARE EXIT HANDLER FOR NOT FOUND RESIGNAL; -- Do the work of the trigger. END And if in your body there occurs an error, it will be thrown back up to the top and exit with an error. This can also be used in stored procedures and whatnot. This works with anything version 5.5+. sh
to handle exceptions or errors encountered in stored procedures.When an error occurs inside a stored procedure, it is important to handle it appropriately, such as continuing or exiting the current code block’s http://www.mysqltutorial.org/mysql-error-handling-in-stored-procedures/ execution, and issuing a meaningful error message.MySQL provides an easy way to define handlers that handle from general conditions such as warnings or exceptions to specific conditions e.g., specific error https://www.devco.net/archives/2007/06/02/handling_update_errors_in_mysql_triggers.php codes.Declaring a handlerTo declare a handler, you use the DECLARE HANDLER statement as follows: DECLARE action HANDLER FOR condition_value statement;1DECLARE action HANDLER FOR condition_value statement;If a condition whose value matches error handling the condition_value , MySQL will execute the statement and continue or exit the current code block based on the action . The action accepts one of the following values:CONTINUE : the execution of the enclosing code block ( BEGIN … END ) continues.EXIT : the execution of the enclosing code block, where the handler is declared, terminates.The condition_value specifies a particular handling in mysql condition or a class of conditions that activates the handler. The condition_value accepts one of the following values:A MySQL error code.A standard SQLSTATE value. Or it can be an SQLWARNING , NOTFOUND or SQLEXCEPTION condition, which is shorthand for the class of SQLSTATE values. The NOTFOUND condition is used for a cursor or SELECT INTO variable_list statement.A named condition associated with either a MySQL error code or SQLSTATE value.The statement could be a simple statement or a compound statement enclosing by the BEGIN and END keywords.MySQL error handling examplesLet’s look into several examples of declaring handlers.The following handler means that if an error occurs, set the value of the has_error variable to 1 and continue the execution. DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET has_error = 1;1DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET has_error = 1;The following is another handler which means that in case any error occurs, rollback the previous operation, issue an error message, and exit the current code block. If you declare it inside the BEGIN END block of a stored procedure, it will terminate stored procedure immediately. DECLARE EXIT HANDLER FOR
whole lot of programming recently and even getting into doing some MySQL stored procedure and trigger programming. I got a copy of the excellent book MySQL Stored Procedure Programming and can recommend it to anyone keen to get information on the subject. Usually when dealing with errors in stored procedures or triggers you define a handler for the MySQL error code and either continue - and presumably do something to handle the exception - or exit with an error. When doing an UPDATE with a WHERE clause that does not match any data though no error gets thrown, it just doesn't do anything. So I tried to come across some samples of how to get the affected row count but came up short - there are very few online resources that I found about MySQL stored procedures in general. So here is a solution for a simple trigger that updates a table when new data arrives in another. DELIMITER $$ CREATE TRIGGER trg_update_latest_on_email_stats AFTER INSERT ON email_stats FOR each row BEGIN DECLARE l_rows INT DEFAULT 0; UPDATE server_stats SET last_email_time = NEW.time WHERE server_name = NEW.server_name; /* how many rows did we affect? */ SELECT ROW_COUNT() INTO l_rows; /* If we didn't update any rows, then insert new data */ IF (l_rows = 0) THEN INSERT INTO server_stats (server_name, last_email_time) VALUES (NEW.server_name, NEW.time); END IF; END $$ That's it, pretty simple stuff. Data comes in, the trigger fires but if there is no data there nothing happens, so it inserts some data and future updates will pass. I could have used the REPLACE function for simpler code, but my solution should be faster which is key when using trigggers. Author R.I. Pienaar Category Code Comments No Comments Leave A Comment Leave a Reply Your email address will not be published. Required fields are marked *Comment Name * Email * Website © 2016 R.I.Pienaar |