Here,when I am passing correct and incorrect value,both the times I am getting result as 4
When I am executing this query
select Count(*) into result
from document_details
where document_name = name
and document_path = path;
then it shows me correct answer which is 1.
Kindly help me ASAP. Thank You in advance!!
create procedure check_status(IN name INT(30),IN path INT(255))
BEGIN
declare result int;
set result = 0;
select Count(*) into result from `document_details` where `document_name`=name and `document_path`=path;
select result;
END
IF types are OK, then that shoud work id not, change then into i.e. (name CHAR(30),path CHAR(255))
create procedure check_status(name INT(30),path INT(255))
BEGIN
select Count(*) as result from `document_details`
where `document_name`=name and `document_path`=path;
END;
In procedures there is no IN/OUT in funcions there are...
Related
I want MySQL outputting a sentence to describe the query results before outputting query results. How to do it?
For example, I want to write a procedure to query information about students with specific names，the name will be passed as argument to the procedure.
this is my snippet of my procedure :
delimiter $$
create procedure show_specific(in student_name text)
begin
declare b_count int default 0;
select count(*) into b_count from students where students.name=student_name;
if(b_count=0)
then select 'Not found';
else
select*
from students where students.name = student_name
end if;
end $$
delimiter ;
Maybe this is not a good example... In this example, if the b_count is zero, this procedure will output 'Not found'. I can use 'print' in SQL server. However MySQL doesn't have 'print' function, Is there similar function in MySQL?
It would help if you described why you want to do this. I don't believe there is any completely equivalent feature in mysql. You can return a warning that the client can see with SHOW WARNINGS by doing:
signal sqlstate '01000' set message_text='message to client';
You just select it:
select 'hello world' as greetings
I try to use subquery in mysql custom user-defined function I get an error so could u help me with one example.
Here is my code:
CREATE DEFINER=`root`#`localhost` FUNCTION `findsubName`(counts INT)
RETURNS varchar(255) CHARSET utf8
BEGIN
DECLARE result VARCHAR(500) DEFAULT NULL;
DECLARE v_name VARCHAR(200);
DECLARE finished INT(1) DEFAULT 0;
DECLARE my_cursor CURSOR FOR
SELECT id, (SELECT t_name FROM ajctb_titles b WHERE a.jt_id=b.t_id)
as tableName FROM ajctb_vacancies a limit counts;
DECLARE CONTINUE HANDLER
FOR NOT FOUND
SET finished = 1;
OPEN my_cursor;
calc_change: LOOP
FETCH my_cursor INTO v_name;
IF finished THEN
LEAVE calc_change;
END IF;
IF result<>'' THEN
SET result = CONCAT_WS(',',result,v_name);
ELSE
SET result = v_name;
END IF;
END LOOP calc_change;
CLOSE my_cursor;
RETURN result;
END
Error message:
Error Code: 1328. Incorrect number of FETCH variables
Error message: Error Code: 1328. Incorrect number of FETCH variables
Error messages attempt to tell you what the problem is. It is in the FETCH. Looking at the documentation:
13.6.6.3 Cursor FETCH Syntax
FETCH [[NEXT] FROM] cursor_name INTO var_name [, var_name] ...
This statement fetches the next row for the
SELECT statement associated with the specified cursor (which must be
open), and advances the cursor pointer. If a row exists, the fetched
columns are stored in the named variables. The number of columns
retrieved by the SELECT statement must match the number of output
variables specified in the FETCH statement.
https://dev.mysql.com/doc/refman/8.0/en/fetch.html
2 columns in your query:
SELECT
id
, (
SELECT
t_name
FROM ajctb_titles b
WHERE a.jt_id = b.t_id
)
AS tableName
means 2 variables are needed the FETCH
It hasn't even attempted the subquery yet.
Regarding that correlated subquery it could be a problem. When you use a subquery in the select clause like this it MUST return no more then one value. So you should use limit 1 if you continue with that subquery.
That subquery can be replaced with a join. e.g.
SELECT
id
, b.t_name AS tableName
FROM ajctb_vacancies a
LEFT JOIN ajctb_titles b ON a.jt_id = b.t_id
You may want to use an INNER JOIN if you must always have a non-null tablename returned.
Is it possible to use a GROUP_CONCAT in a SELECT as the input of a MySQL function? I cannot figure out how to cast the variable it seems. I've tried blob. I've tried text (then using another function to break it up into a result set, here) but I haven't had any success.
I want to use it like this:
SELECT
newCustomerCount(GROUP_CONCAT(DISTINCT items.invoicenumber)) AS new_customers
FROM items;
Here is the function:
DROP FUNCTION IF EXISTS newCustomerCount;
DELIMITER $$
CREATE FUNCTION newCustomerCount(invoicenumbers BLOB)
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE new_customers INT;
SET new_customers = 0;
SELECT
SUM(nc.record) INTO new_customers
FROM (
SELECT
1 AS customer,
(SELECT COUNT(*) FROM person_to_invoice ps2 WHERE person_id = ps1.person_id AND invoice < ps1.invoice) AS previous_invoices
FROM person_to_invoice ps1
WHERE invoice IN(invoicenumbers)
HAVING previous_invoices = 0
) nc;
RETURN new_customers;
END$$
DELIMITER ;
Because Mysql functions do not support dynamic queries, I recommend you re-think your basic strategy to pass in a list of invoice numbers to your function. Instead, you could modify your function to accept a single invoice number and return the number of new customers just for the one invoice number.
Also, there are some optimizations you can make in your query for finding the number of new customers.
DROP FUNCTION IF EXISTS newCustomerCount;
DELIMITER $$
CREATE FUNCTION newCustomerCount(p_invoice INT)
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE new_customers INT;
SET new_customers = 0;
SELECT
COUNT(DISTINCT ps1.person_id) INTO new_customers
FROM
person_to_invoice ps1
WHERE
ps1.invoice = p_invoice
AND NOT EXISTS (
SELECT 1
FROM person_to_invoice ps2
WHERE ps1.person_id = ps2.person_id
AND ps2.invoice < ps1.invoice
);
RETURN new_customers;
END$$
DELIMITER ;
Then you can still get the total number of new customers for a given list of invoice numbers like this:
SELECT
SUM(newCustomerCount(invoice)) as total_new_customers
FROM items
WHERE ...
You could try FIND_IN_SET() instead of IN(). The performance will probably be horrible when passing in a long list of invoice numbers. But it should work.
WHERE FIND_IN_SET(invoice, invoicenumbers)
You are looking in the wrong place.
WHERE invoice IN(invoicenumbers) will not do the desired substitution. Instead you need to use CONCAT to construct the SQL, then prepare and execute it.
A rather simple question, but I can only find answers to more complex questions.
I'm working on a stored procudure and am currently inside a REPEAT loop. I need to run the following query in the loop to get the 1 column value that is returned (only 1 record will be returned). This will need to be stored as a var to be used later in the loop.
SELECT photo_id FROM photos ORDER BY photo_id DESC LIMIT 1;
How do I set that to 'last_photo_id' to be used later in the stored procdure?
You could do something like this:
SELECT #varname := photo_id
FROM photos
ORDER BY photo_id DESC
LIMIT 1;
That is, if you are sure there's no other way to do what you want to do than in a loop. For SQL works best when you use it for set-based solutions.
Try this:
DECLARE total_products INT DEFAULT 0
SELECT COUNT INTO total_products
FROM products
You can use a function
So for example
SET i_camera_count = get_camera_count(i_photo_camera_data_id);
and then make a function like this.
DELIMITER $$
DROP FUNCTION IF EXISTS `get_camera_count` $$
CREATE DEFINER=`root`#`localhost` FUNCTION `get_camera_count`(camera_id_2 INT(10)) RETURNS int(11)
BEGIN
DECLARE v_return_val INT;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_return_val = -1;
SELECT x FROM y WHERE camera_id = camera_id_2
RETURN v_return_val;
END $$
DELIMITER ;
So, I'm making my first MySQL function.
BEGIN
DECLARE ID INT;
SELECT
LandID INTO ID
FROM
Landen
WHERE
Landnaam = landnaam;
RETURN ID;
END
The parameter is a varchar.
So, let's say I got a record in Landen with the Landnaam 'Nederland'.
I run my function, give 'Nederland' as parameter.
But then it gives me to following error:
1172 - result consisted of more than one row
Which makes no sense at all. Cause when I give something as a parameter that is not in my database, like 'ASDASD', I get the same error.
And when limmiting the results with
LIMIT 1
It just always returns 1.
What am I doing wrong?
drop function if exists myfunc;
delimiter //
create function myfunc(str varchar(50))
returns int
reads sql data
begin
declare id int;
select landid into id from Landen where landnaam = str limit 1;
return id;
end//
delimiter ;
select myfunc('nederland');