Print debugging info from stored procedure in MySQL

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Is there a way in MySQL to print debugging messages to stdout, temptable or logfile? Something like:

  • print in SQLServer
  • DBMS_OUTPUT.PUT_LINE in Oracle

Option 1: Put this in your procedure to print 'comment' to stdout when it runs.

SELECT 'Comment';

Option 2: Put this in your procedure to print a variable with it to stdout:

declare myvar INT default 0;
SET myvar = 5;
SELECT concat('myvar is ', myvar);

This prints myvar is 5 to stdout when the procedure runs.

Option 3, Create a table with one text column called tmptable, and push messages to it:

declare myvar INT default 0;
SET myvar = 5;
insert into tmptable select concat('myvar is ', myvar);

You could put the above in a stored procedure, so all you would have to write is this:

CALL log(concat('the value is', myvar));

Which saves a few keystrokes.

Option 4, Log messages to file

select "penguin" as log into outfile '/tmp/result.txt';

There is very heavy restrictions on this command. You can only write the outfile to areas on disk that give the 'others' group create and write permissions. It should work saving it out to /tmp directory.

Also once you write the outfile, you can't overwrite it. This is to prevent crackers from rooting your box just because they have SQL injected your website and can run arbitrary commands in MySQL.

Lesson 2: Debugging a stored procedure, How do you return a value from a stored procedure in MySQL? 7.10 Debugging Stored Procedures and Functions The stored procedure debugger provides facilities for setting breakpoints, stepping into individual statements (Step Into, Step Out, Step Over), evaluating and changing local variable values, evaluating breakpoints, and other debugging tasks.


One workaround is just to use select without any other clauses.

http://lists.mysql.com/mysql/197901

How do you debug MySQL stored procedures?, & Functions. Right-click Debugger_Tutorial (GROUPO) and click Execute From Interactive SQL. This is an incorrect result. The remainder of the tutorial diagnoses the error that produced this result. A stored procedure can be significantly faster than a Java program which might make multiple calls to the database. A stored procedure can be more secure. Regardless of the reasons for choosing to write a stored procedure, the problem remains of how to debug one.


I usually create log table with a stored procedure to log to it. The call the logging procedure wherever needed from the procedure under development.

Looking at other posts on this same question, it seems like a common practice, although there are some alternatives.

Debugging MySQL Stored Procedures, I do something very similar to you. I'll usually include a DEBUG param that defaults to false and I can set to true at run time. Then wrap the  I have a MySQL stored procedure with a few cursors. I want to print a value to send output back to the client. SQLyog Enterprise.. I tried declaring a variable as TEXT and concatenating inside the loop but that does not work, at least not the way I was trying to do it.


Quick way to print something is:

select '** Place your mesage here' AS '** DEBUG:';

Debugging MySQL Procedures, In this kind of situation simply bench testing the SQL statements does not really test the procedure. Insert print statements in your Stored  For debugging info from stored procedure in MySQL,there are following options through which you can do this. 1.Write into the file externally: select "your_message" as log into outfile '/temp/brajesh.txt'; 2.Use select command to print message: select "result_message"; 3.Use select command to print additional information with message:


This is the way how I will debug:

CREATE PROCEDURE procedure_name() 
BEGIN
    DECLARE EXIT HANDLER FOR SQLEXCEPTION
    BEGIN
        SHOW ERRORS;  --this is the only one which you need
        ROLLBACK;   
    END; 
    START TRANSACTION;
        --query 1
        --query 2
        --query 3
    COMMIT;
END 

If query 1, 2 or 3 will throw an error, HANDLER will catch the SQLEXCEPTION and SHOW ERRORS will show errors for us. Note: SHOW ERRORS should be the first statement in the HANDLER.

Debugging MySQL Stored Procedures, asked how they could debug runtime variable values in a MySQL Stored Procedure You enable output display in Oracle by setting this in SQL*Plus: you've performed two or more SQL statements that may modify data. A student asked how they could debug runtime variable values in a MySQL Stored Procedure (or subroutines according to some documentation). You can see this post for how to create an equivalent solutions for MySQL functions. In Oracle, we debug with the DBMS_OUTPUT package.


MySQL stored procedures: all ways to produce an output, Upon launching the application, you'll be greeted by the Connection dialog. Enter the connection information for the sakila schema and click the  To observe the runtime behavior of a stored routine and debug any problems, use the Stored Procedure Debugger. For additional information, see Section 7.10, “Debugging Stored Procedures and Functions”.


How to Log Debug Information About a Stored Procedure , Since MySQL has no native debugger for stored procedures, there is a So the schema of the data can actually be decided by the procedure  I meant `procname=’p1′, args=[]`. The args is a list of your stored procedure arguments, which is empty in my p1 example. Also, a stored procedure can return not only one, but multiple result sets if you want (just use multiple SELECTs in the stored procedure body), so `cursor.stored_results()` will actually return a list of result sets.


Chapter 11, Debugging Stored Procedures and Functions, We have a group of fairly complex stored procedures that process a transaction queue on a round the clock schedule. These scripts use a number of print  Chapter 11 Debugging Stored Procedures and Functions The stored procedure debugger provides facilities for setting breakpoints, stepping into individual statements (Step Into, Step Out, Step Over), evaluating and changing local variable values, evaluating breakpoints, and other debugging tasks.