Convert postgresql trigger to mysql trigger - mysql

I'm trying to transpose a postgres trigger to a mysql trigger. It automatically adds fields to the row according to the date added
CREATE FUNCTION convert_date ()
RETURNS trigger
AS $$
declare
date_min DATE;
date_max DATE;
temp_year INTEGER;
begin
SELECT SUBSTRING(NEW."dc_date_label",0,5)::integer
INTO temp_year;
SELECT date(temp_year || '-01-10')
INTO date_min;
SELECT date(temp_year +1 || '-09-30')
INTO date_max;
NEW."dc_date_start" = date_min;
NEW."dc_date_end" = date_max;
RETURN new;
end;
CREATE TRIGGER trig_b_i_compute_date()
BEFORE INSERT
ON campaigns
FOR EACH ROW
EXECUTE PROCEDURE convert_date();
This is what i've done on mysql :
DELIMITER //
CREATE TRIGGER trig_b_i_compute_date
BEFORE INSERT ON campaigns
FOR EACH ROW
BEGIN
DECLARE date_min DATE;
DECLARE date_max DATE;
DECLARE temp_year INTEGER;
SET temp_year = SELECT CONVERT( SUBSTRING(NEW.dc_date_label,1,5), UNSIGNED INTEGER) ;
SET date_min = SELECT CONVERT( CONCAT(temp_year,'-01-10'), DATE);
SET date_max = SELECT CONVERT( CONCAT(temp_year + 1, '09-30'), DATE);
SET NEW.dc_date_start = date_min;
SET NEW.dc_date_end = date_max;
END;
//
DELIMITER ;
However I get an error :
MySQL server version for the right syntax to use near 'SELECT CONVERT( SUBSTRING(NEW.dc_date_label,1,5), UNSIGNED INTEGER) ;
What is wrong with the procedure ?

If you use SELECT in a SET statement, you need to put it in parentheses:
SET temp_year = (SELECT ...);
But in your case you don't need a SELECT and you can just skip it:
SET temp_year = CONVERT(...);
You can also use the SELECT INTO syntax in MySQL:
SELECT CONVERT(...) INTO temp_year;
And there is no need to declare date_min and date_max. Also no need to cast everything explicitly. Your trigger body could be:
DECLARE temp_year INTEGER;
SET temp_year = CONVERT( SUBSTRING(NEW.dc_date_label,1,5), UNSIGNED);
SET NEW.dc_date_start = CONCAT(temp_year, '-01-10');
SET NEW.dc_date_end = CONCAT(temp_year + 1, '-09-30');
I don't know how dc_date_label looks like, and why the year should be 5 characters long. So I kept the year extraction as it is. But if it's a DATE, DATETIME or TIMESTAMP, you can just use the YEAR function:
SET temp_year = YEAR(NEW.dc_date_label);
And since it's much shorter, you could also use it inline and skip the temp_year variable:
SET NEW.dc_date_start = CONCAT(YEAR(NEW.dc_date_label), '-01-10');
SET NEW.dc_date_end = CONCAT(YEAR(NEW.dc_date_label) + 1, '-09-30');
And last one: Remove the semicolon after END. It might work, but it doesn't belong there.

Related

how does mysql user defined function know a selected row was found?

a MYSQL user defined function selects a row from a table. How does the UDF code determine if the selected row was found in the table?
CREATE FUNCTION snippetFolder_folderPath(folder_id int)
RETURNS varchar(512)
BEGIN
declare vFolder_id int;
declare vParent_id int;
declare vPath varchar(512) default '';
declare vFolderName varchar(256) default '';
set vFolder_id = folder_id;
build_path:
while (vFolder_id > 0) do
/* -------- how to know this select statement returns a row?? ---------- */
select a.parent_id, a.folderName
into vParent_id, vFolderName
from SnippetFolder a
where a.folder_id = vFolder_id;
if vPath = ' ' then
set vPath = vFolderName;
else
set vPath = concat_ws( '/', vFolderName, vPath );
end if ;
set vFolder_id = vParent_id;
end while ;
return vPath;
END
https://dev.mysql.com/doc/refman/8.0/en/select-into.html says:
If the query returns no rows, a warning with error code 1329 occurs (No data), and the variable values remain unchanged.
So you could declare a continue handler on warnings, something like the example from the documentation:
BEGIN
DECLARE i INT DEFAULT 3;
DECLARE done INT DEFAULT FALSE;
retry:
REPEAT
BEGIN
DECLARE CONTINUE HANDLER FOR SQLWARNING
BEGIN
SET done = TRUE;
END;
IF done OR i < 0 THEN
LEAVE retry;
END IF;
SET i = i - 1;
END;
UNTIL FALSE END REPEAT;
END
I'll leave it to you to read the documentation and adapt that example to your table and your loop.
Alternatively, if you're using MySQL 8.0 you can use recursive common table expression:
CREATE FUNCTION snippetFolder_folderPath(vFolder_id int)
RETURNS varchar(512)
BEGIN
DECLARE vPath varchar(512) DEFAULT '';
WITH RECURSIVE cte AS (
SELECT folderName, parent_id, 0 AS height
FROM SnippetFolder WHERE folder_id = vFolder_id
UNION
SELECT f.folderName, f.parent_id, cte.height+1
FROM SnippetFolder AS f JOIN cte ON cte.parent_id = f.folder_id
)
SELECT GROUP_CONCAT(folderName ORDER BY height DESC SEPARATOR '/')
INTO vPath
FROM cte;
RETURN vPath;
END
The recursive CTE result is all the ancestors of the row matching vFolder_id, and then one can use GROUP_CONCAT() to concatenate them together as one string.

MYSQL Conditional Always Evaluating to Else

The below MYSQL conditional from a trigger is always evaluating to the ELSE statement after I have verified the numbers are as expected. If I make the following assumptions: NEW.exit_time = '2019-04-09 11:50:00', OLD.enter_time = '2019-04-09 11:00:00' I expect time_in_minutes = 50, which should then SET NEW.total = 25 if plot_minimum_cost = 25. I have verified that the select statements populating plot_minimum_cost and plot_minute_cost are accurate given that plot_max_cost is functioning correctly and it is using the same logic to retrieve. What am I missing?
DROP TRIGGER IF EXISTS get_total_parking_cost;
DELIMITER $$
CREATE TRIGGER get_total_parking_cost BEFORE UPDATE
ON records
FOR EACH ROW
BEGIN
DECLARE plot_minimum_cost DOUBLE;
DECLARE plot_max_cost DOUBLE;
DECLARE plot_minute_cost DOUBLE;
DECLARE time_in_lot DATETIME;
DECLARE time_in_minutes DOUBLE;
SELECT parking_lots.min_cost INTO plot_minimum_cost
FROM parking_lots
WHERE parking_lots.id = OLD.parking_id;
SELECT parking_lots.max_cost INTO plot_max_cost
FROM parking_lots
WHERE parking_lots.id = OLD.parking_id;
SELECT parking_lots.minutely_cost INTO plot_minute_cost
FROM parking_lots
WHERE parking_lots.id = OLD.parking_id;
SET #time_in_lot = TIMEDIFF(NEW.exit_time, OLD.enter_time);
SET #time_in_minutes = (HOUR(time_in_lot) * 60) + MINUTE(time_in_lot);
IF #time_in_minutes <= 60 THEN
SET NEW.total = plot_minimum_cost;
ELSEIF #time_in_minutes <= 300 THEN
SET NEW.total = time_in_minutes * plot_minute_cost;
ELSE
SET NEW.total = plot_max_cost;
END IF;
END$$
DELIMITER ;
You've declared the local variable time_in_lot and are using it in (HOUR(time_in_lot) * 60) + MINUTE(time_in_lot); but you never actually set it. You set #time_in_lot which is a session variable. Similarly, you are setting #time_in_minutes even though you've declared an time_in_minutes; but in that case you are using the # version for the IF conditions.
Basically, remove all instances of the # character from the trigger and see if that fixes it.

error in stored procedure ...into keyword

Two tables Borrower(rollno,name,bookissue_date) and Fine(rollno,name,amount)
delimiter //
create procedure student( in roll_no int,in Nameofbook varchar(40))
begin
declare Dateofiss1 date;
Declare cur cursor for
select Dateofiss from Borrower where Roll_no = roll into Dateofiss1;
OPEN cur;
fetch cur into Dateofiss1
if(datediff(sysdate(),Dateofiss1)<15) then varchar(20))
update Borrower set status='R'where Roll_no=roll_no
elseif(datediff(sysdate(),Dateofiss1)>=15)and datediff (sysdate(),Dateofiss1<30)
SET FINEAMOUNT=5*(datediff(sysdate(),Dateofiss1)-15)
insert into Fine(Roll_no,Date,amount)values(rollno,sysdate,fineamount);
update.borrower set status='R' where Roll_no='rollno';
elseif (datediff(sysdate(),Dateofiss1)>30)
SET FINEAMOUNT=50*(datediff(sysdate(),Dateofiss1)-15)
insert into Fine(Roll_no,Date,amount)values(rollno,sysdate,fineamount);
update.borrower set status='R' where Roll_no='rollno';
close cur;
end if
select * from Borrower;
elect * from Fine;
end
You have a number of syntax errors.
You have an extraneous varchar(20)) in the first if statement.
You're missing THEN in the ELSEIF statements.
You wrote update.borrower instead of update borrower.
You have roll_no in quotes in some of your update statements.
The roll_no parameter is the same as a table column, since column names are case-insensitive. The condition where Roll_no = roll_no will match every row because of this. Give the parameter a different name.
In a SELECT, the INTO clause goes after FROM, not at the end.
There's no need to use a cursor if you're using SELECT INTO. Just execute the query and it will set the variable.
You can also simplify the code by putting the date difference in a variable, so you don't have to repeatedly calculate it. And in the ELSEIF you don't need to test >= 15, since you'll only get there if the < 15 test failed.
The UPDATE statement is the same in all conditions, so it doesn't need to be in the IF at all.
delimiter //
create procedure student( in p_roll_no int,in Nameofbook varchar(40))
begin
declare Dateofiss1 date;
declare diff INT;
select Dateofiss from Borrower into Dateofiss1 where Roll_no = p_roll_no;
OPEN cur;
SET diff = datediff(sysdate(),Dateofiss1)
IF diff BETWEEN 15 AND 29 THEN
SET FINEAMOUNT= 5 * (diff - 15)
insert into Fine(Roll_no,Date,amount)values(rollno,sysdate,fineamount);
else
SET FINEAMOUNT= 50 * (diff - 15)
insert into Fine(Roll_no,Date,amount)values(rollno,sysdate,fineamount);
end if
update Borrower set status='R'where Roll_no=p_roll_no
select * from Borrower;
select * from Fine;
end

How to convert TSQL query into MYSQL query?

I have developed a function for split string in tsql but mysql don't have some built in functions. I needed to function in MYSQL as i am new in mysql. Function should accept 2 parameters
1. String to be split
2. separator (',' or whatever)
Kindly reply me.
i had found solution on the internet you can into that.
DELIMITER //
DROP FUNCTION IF EXISTS `splitAndTranslate` //
CREATE FUNCTION splitAndTranslate(str TEXT, delim VARCHAR(124))
RETURNS TEXT
DETERMINISTIC
BEGIN
DECLARE i INT DEFAULT 0; -- total number of delimiters
DECLARE ctr INT DEFAULT 0; -- counter for the loop
DECLARE str_len INT; -- string length,self explanatory
DECLARE out_str text DEFAULT ''; -- return string holder
DECLARE temp_str text DEFAULT ''; -- temporary string holder
DECLARE temp_val VARCHAR(255) DEFAULT ''; -- temporary string holder for query
-- get length
SET str_len=LENGTH(str);
SET i = (LENGTH(str)-LENGTH(REPLACE(str, delim, '')))/LENGTH(delim) + 1;
-- get total number delimeters and add 1
-- add 1 since total separated values are 1 more than the number of delimiters
-- start of while loop
WHILE(ctr<i) DO
-- add 1 to the counter, which will also be used to get the value of the string
SET ctr=ctr+1;
-- get value separated by delimiter using ctr as the index
SET temp_str = REPLACE(SUBSTRING(SUBSTRING_INDEX(str, delim, ctr), LENGTH(SUBSTRING_INDEX(str, delim,ctr - 1)) + 1), delim, '');
-- query real value and insert into temporary value holder, temp_str contains the exploded ID
SELECT <real_value_column> INTO temp_val FROM <my_table> WHERE <table_id>=temp_str;
-- concat real value into output string separated by delimiter
SET out_str=CONCAT(out_str, temp_val, ',');
END WHILE;
-- end of while loop
-- trim delimiter from end of string
SET out_str=TRIM(TRAILING delim FROM out_str);
RETURN(out_str); -- return
END//
reference http://www.slickdev.com/2008/09/15/mysql-query-real-values-from-delimiter-separated-string-ids/
In mysql they they dont support some functionality like sqlserver. so spliting will be difficult in mysql
SELECT e.`studentId`, SPLIT(",", c.`courseNames`)[e.`courseId`]
FROM ..
SELECT TRIM(SUBSTRING_INDEX(yourcolumn,',',1)), TRIM(SUBSTRING_INDEX(yourcolumn,',',-1)) FROM yourtable
CREATE FUNCTION [dbo].[SplitString]
(
#RowData nvarchar(2000),
#SplitOn nvarchar(5)
)
RETURNS #RtnValue table
(
--Id int identity(1,1),
Data nvarchar(100)
)
AS
BEGIN
Declare #Cnt int
Set #Cnt = 1
While (Charindex(#SplitOn,#RowData)>0)
Begin
Insert Into #RtnValue (data)
Select
Data = ltrim(rtrim(Substring(#RowData,1,Charindex(#SplitOn,#RowData)-1)))
Set #RowData = Substring(#RowData,Charindex(#SplitOn,#RowData)+1,len(#RowData))
Set #Cnt = #Cnt + 1
End
Insert Into #RtnValue (data)
Select Data = ltrim(rtrim(#RowData))
Return
END

Shuffle a string with mysql/sql

I was wondering, if there is some way to shuffle the letters of a string in mysql/sql, i.e. something like the pseudocode: SELECT SHUFFLE('abcdef')?
Couldn't find any from http://dev.mysql.com/doc/refman/5.0/en/string-functions.html and searching for it just seems to find solutions for shuffling results, not a string.
Here you go:
DELIMITER //
DROP FUNCTION IF EXISTS shuffle //
CREATE FUNCTION shuffle(
v_chars TEXT
)
RETURNS TEXT
NOT DETERMINISTIC -- multiple RAND()'s
NO SQL
SQL SECURITY INVOKER
COMMENT ''
BEGIN
DECLARE v_retval TEXT DEFAULT '';
DECLARE u_pos INT UNSIGNED;
DECLARE u INT UNSIGNED;
SET u = LENGTH(v_chars);
WHILE u > 0
DO
SET u_pos = 1 + FLOOR(RAND() * u);
SET v_retval = CONCAT(v_retval, MID(v_chars, u_pos, 1));
SET v_chars = CONCAT(LEFT(v_chars, u_pos - 1), MID(v_chars, u_pos + 1, u));
SET u = u - 1;
END WHILE;
RETURN v_retval;
END;
//
DELIMITER ;
SELECT shuffle('abcdef');
See sqlfiddle.com for the output.
Tested successfully with mariadb 10.1 (mysql 5.6 equivalent)
Edit: this solution is for Microsoft SQL Server.
As it's not allowed to use RAND() in user defined function, we create a view to use it later in our shuffle function:
CREATE VIEW randomView
AS
SELECT RAND() randomResult
GO
The actual shuffle function is as following:
CREATE FUNCTION shuffle(#string NVARCHAR(MAX))
RETURNS NVARCHAR(MAX) AS
BEGIN
DECLARE #pos INT
DECLARE #char CHAR(1)
DECLARE #shuffeld NVARCHAR(MAX)
DECLARE #random DECIMAL(18,18)
WHILE LEN(#string) > 0
BEGIN
SELECT #random = randomResult FROM randomView
SET #pos = (CONVERT(INT, #random*1000000) % LEN(#string)) + 1
SET #char = SUBSTRING(#string, #pos, 1)
SET #shuffeld = CONCAT(#shuffeld, #char)
SET #string = CONCAT(SUBSTRING(#string, 1, #pos-1), SUBSTRING(#string, #pos+1, LEN(#string)))
END
RETURN #shuffeld
END
Calling the function
DECLARE #string NVARCHAR(MAX) = 'abcdefghijklmnonpqrstuvwxyz0123456789!"ยง$%&/()='
SELECT dbo.shuffle(#string)
There is nothing in standard SQL - your best bet is probably to write a user defined function