i came across a procedure with this code
DELIMITER $$
Create PROCEDURE Procedure1 (IN A int)
BEGIN
DECLARE n int DEFAULT 0;
DECLARE i int DEFAULT 0;
DECLARE column_int int DEFAULT NULL;
SELECT
COUNT(1)
FROM table1 t1
WHERE t1.id = A INTO n;
WHILE i < n DO
SELECT
t1.B
FROM table1 t1
WHERE t1.id = A
ORDER BY t1.id
LIMIT i, 1 INTO column_int;
CALL Procedure2(A, column_int);
SET i = i + 1;
END WHILE;
END
$$
DELIMITER;
i don't understand the while part of the code, if we are limiting by i , the first run should give no records ( as i would be 0), and since n will be 1 ( from the first part of the query where count(1) is inserting in n ) how will i<n work ? how will limit i work here ?
i is being used to set the offset so it stepping through table1 1 row at a time until i reaches number of rows in table.
the full form of limit is limit offset,number
Related
I have a stored procedure that insert data related to a scooter rent, one of the fields is a "rent code" when i insert the information "rent code" should be a unique random number that don exist in the table "rents"
here is that i tried
SELECT FLOOR(RAND() *9999)+1 AS random_num
FROM reservaciones
WHERE "random_num" NOT IN (SELECT reservaciones.Codigo_Reservacion FROM reservaciones)
LIMIT 1
in the table i got
1
2
3
when i run the code if i reduce the limit to 4 (example) the query still generates the numbers that i already got in my table
Create and use user-defined function similar to:
CREATE FUNCTION generate_random_number (upper_limit INT)
RETURNS INT
BEGIN
IF upper_limit = (SELECT COUNT(*) FROM main_table WHERE id <= upper_limit) THEN
RETURN NULL;
END IF;
IF upper_limit IS NULL THEN
SELECT REPEAT('9', LENGTH(MAX(id) + 1)) FROM main_table INTO upper_limit;
END IF;
RETURN (SELECT t1.id + 1
FROM (SELECT id FROM main_table
UNION ALL
SELECT 0) t1
LEFT JOIN main_table t2 ON t1.id = t2.id - 1
WHERE t2.id IS NULL
AND t1.id < upper_limit
ORDER BY RAND() LIMIT 1);
END
upper_limit parameter specifies the range from which the number should be generated. Can be less than max. existing value. Cannot be greater than 2147483647. Cannot be set to NULL if max. existing value is 999999999 or greater (you may expand this limit by set the parameter and output datatypes to BIGINT).
Function returns NULL if there is no free number in specified range.
fiddle with some comments.
I have a routine. But it' s too slow. How can I improve the query?
My records: http://www.sqlfiddle.com/#!9/14cceb/1/0
My query:
CREATE DEFINER = 'root'#'localhost'
PROCEDURE example.ssa()
BEGIN
drop table if exists gps_table;
drop table if exists exam_datas;
CREATE TEMPORARY TABLE gps_table(ID int PRIMARY KEY AUTO_INCREMENT,timei
int,
trun_date_time datetime, tadd_meter int, tin_here int null);
insert into gps_table(timei,trun_date_time,tadd_meter,tin_here) select
imei, run_date_time, add_meter, in_here from example_table;
CREATE TEMPORARY TABLE exam_datas(ID int PRIMARY KEY AUTO_INCREMENT,vimei
int, vbas_run_date_time datetime, vbit_run_date_time datetime, vdifff int);
select tin_here from gps_table limit 1 into #onceki_durum;
select count(id) from gps_table into #kayit_sayisi;
set #i = 1;
set #min_mes = 0;
set #max_mes = 0;
set #frst_id = 0;
set #imei = 0;
set #run_date_time = '0000-00-00 00:00:00';
set #run_date_time2 = '0000-00-00 00:00:00';
myloop: WHILE (#i <= #kayit_sayisi) DO
select tin_here from gps_table where id = #i into #in_here_true;
if (#in_here_true = 1) then
select id,trun_date_time, tadd_meter from gps_table where id = #i into #frst_id,#run_date_time2, #min_mes;
select id from gps_table where id > #frst_id and tin_here =0 order by id asc limit 1 INTO #id;
SET #id = #id-1;
select id, timei, trun_date_time, tadd_meter from gps_table
where id = #id and tin_here =1 limit 1 into #i, #imei, #run_date_time, #max_mes;
if(#i-#frst_id>3) then
set #i:=#i+1;
insert into exam_datas(vimei,vbas_run_date_time,vbit_run_date_time,vdifff) Values (#imei, #run_date_time2, #run_date_time, #max_mes-#min_mes);
SELECT * FROM exam_datas;
SET #asd =1;
elseif 1=1 then
set #i:=#i+1;
End if;
ELSEIF 1=1
THEN SET #i:=#i+1;
End if;
IF (#i = #kayit_sayisi)
THEN set #tamam =1; LEAVE myloop;
END IF;
END WHILE myloop;
select DISTINCT * from exam_datas;
drop table if exists exam_datas;
drop table if exists gps_table;
END
I need: id= 6 first true and id= 11 last_true
firs_trure - last_true = 304-290= 14
id=14 first true and id=18 last_true
firs_true - last_true = 332-324= 8
This routine is too slow.
MySql version is 5.7 and There are 2 milions record in the table.
UPDATE:
Query is here. HERE
Thank you #LukStorms
It's possible to get such results in 1 query.
Thus avoiding a WHILE loop over records.
This example works without using window functions. Just using variables inside the query to calculate a rank. Which is then used to get the minimums and maximums of the groups.
select
imei,
min(run_date_time) as start_dt,
max(run_date_time) as stop_dt,
max(add_meter) - min(add_meter) as diff
from
(
select imei, id, run_date_time, add_meter, in_here,
case
when #prev_imei = imei and #prev_ih = in_here then #rnk
when #rnk := #rnk + 1 then #rnk
end as rnk,
#prev_imei := imei as prev_imei,
#prev_ih := in_here as prev_ih
from example_table t
cross join (select #rnk := 0, #prev_ih := null, #prev_imei := null) vars
order by imei, id, run_date_time
) q
where in_here = 1
group by imei, rnk
having count(*) > 4
order by imei, min(id);
In the procedure such query can be used to fill that final temporary table.
A test on db<>fiddle here
I have problem with my procedure. I have table oferty_in which contain fields (id, status, ..., id_om). I want procedure which check if exist rows with the same id_om.
If exist, delete rows where status = 'N' (N - new).
My procedure almost works, but i have problem with iterate in loop. Every time I run my procedure ,procedure delete a half of rows. I don't know where is problem...
DELIMITER //
CREATE PROCEDURE check_duplicates_oferty_in()
BEGIN
DECLARE n INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DECLARE v_id_del BIGINT;
SELECT count(*) INTO n FROM oferty_in where status_oferty = 'N';
SET i=0;
WHILE i<n DO
IF EXISTS (SELECT id_om FROM oferty_in group by id_om having count(*) >= 2 LIMIT i,1) THEN
SELECT id_om INTO v_id_del FROM oferty_in group by id_om having count(*) >= 2 LIMIT i,1;
DELETE from oferty_in where id_om = v_id_del and status_oferty = 'N';
END IF;
SET i=i+1;
END WHILE;
END
//
I try also:
IF EXISTS (SELECT id_om FROM oferty_in group by id_om having count(*) >= 2 LIMIT i,1) THEN
SELECT id_om INTO v_id_del FROM oferty_in group by id_om having count(*) >= 2 LIMIT i,1;
DELETE from oferty_in where id_om = v_id_del and status_oferty = 'N';
SET i=i+1;
ELSE
SET i=i+1;
END IF;
But it's the same.
Every time half of rows. I use counter 'i' and while loop to iterate row by row on rows in oferty_in when status = 'N'. Anyone have a idea what I did wrong? Thanks for help and time.
You seem to want to delete rows with status = 'N' when id_om is duplicated.
I want procedure which check if exist rows with the same id_om. If exist, delete rows where status = 'N' (N - new).
Non-working code doesn't generally help explain logic, so this is what I am going by.
You definitely do not need a looping construct for this, nor a cursor:
delete o
from oferty_in o join
(select o2.id_om
from oferty_in o2
group by o2.id_om
having count(*) > 1 and sum(status = 'N') > 0
) o2
on o.id_om = o2.id_om
where o.status = 'N';
I want a query to insert a row into a table I know it is simple but the scenario is the table should not have more than 5 rows. If table has more than five rows I need to remove the old row(Or replace with new row ) (Based on the insert time stamp) then i need to insert a new row.If number of rows less than count 5 then i can directly insert a row.
Please share me the query.
How about something like this.
declare #count int
SELECT #count=COUNT(*)
from EP_ANSWERS
IF (#count<5)
// DO your insert here
ELSE
DELETE FROM TABLE
WHERE inserttimestamp = (SELECT x.inserttimestamp
FROM (SELECT MAX(t.inserttimestamp) AS inserttimestamp
FROM TABLE t) x)
// DO your insert here
If it is impossible for the table to have more than 5 rows:
DELETE FROM yourtable
WHERE 5 <= (SELECT COUNT(*) FROM yourtable)
AND yourtimestamp = (SELECT MIN(yourtimestamp) FROM yourtable)
;
INSERT INTO yourtable ...
;
If it is possible for the table to have more than 5 rows:
DELETE FROM yourtable
WHERE 5 <= (SELECT COUNT(*) FROM yourtable)
AND yourtimestamp NOT IN (SELECT yourtimestamp
FROM yourtable
ORDER BY yourtimestamp DESC
LIMIT 4)
;
INSERT INTO yourtable ...
;
It sounds like you want to put a trigger on the table to maintain this rule, in MySQL the something like this should work
CREATE TRIGGER trg__my_table__limit_rows
BEFORE INSERT
ON my_table
FOR EACH ROW
BEGIN
IF ((SELECT COUNT(1) FROM my_table) = 5)
BEGIN
DELETE FROM my_table
WHERE id = (SELECT MIN(id) FROM my_table) -- change this to fit your logic for which record should be removed
END
END
Some of the code here is in pseudo (you didn't wrote your schema), but i wrote where you need to complete your own code.
DECLARE #NumberOfRowsToInsert INT = -- select from the data you want to insert
DECLARE #MaxNumberOfRows INT = 5
DECLARE #NumberOfExistingRows INT
DECLARE #Query VARCHAR(MAX) = 'SELECT TOP #rows id FROM SomeTable ORDER BY createdDate ASC'
SELECT #NumberOfExistingRows = COUNT(*)
FROM SomeTable
SET #Query = REPLACE(#Query,'#rows',
CAST(#NumberOfRowsToInsert - (#MaxNumberOfRows - #NumberOfExistingRows))) AS VARCHAR(1))
CREATE TABLE #IdsToDelete(id INT PRIMARY KEY)
INSERT INTO #IdsToDelete
EXEC(#Query)
DELETE FROM SomeTable
WHERE id IN (SELECT * FROM #IdsToDelete)
-- insert here..
I have the query working, just wondering if there is a better way to do this without cursors/loops/php side. I've been a DBA for 5+ years and just came across the := statement. Very cool.
Table (tblPeople) with the person ID and the number of tickets they bought.
PersonId NumTickets
1 3
2 1
3 1
I then want to assign individual tickets to each person in a new table (tblTickets), depending on how many tickets they bought. The TicketId is a key, auto increment column.
TicketId PersonId
100 1
101 1
102 1
103 2
104 3
Here is the code. It loops through the whole tblPeople over and over again incrementing a new calculated column called rowID. Then I filter out the rows based on the number of tickets they bought in the WHERE clause. The problem I see is the subquery is huge, the more people I have, the bigger the subquery gets. Just not sure if there is a better way to write this.
INSERT INTO tblTickets (PersonId)
SELECT PersonId
FROM (
SELECT s.PersonId, s.NumTickets,
#rowID := IF(#lastPersonId = s.PersonId and #lastNumTickets = s.NumTickets, #rowID + 1, 0) AS rowID,
#lastPersonId := s.PersonId,
#lastNumTickets := s.NumTickets
FROM tblPeople m,
(SELECT #rowID := 0, #lastPersonId := 0, #lastNumTickets := 0) t
INNER JOIN tblPeople s
) tbl
WHERE rowID < NumTickets
I'd add a utility table Numbers which contains all the numbers from 1 up to the maximal number of tickets a person may buy. Then you can do something like this:
INSERT INTO tblTickets (PersonId)
SELECT s.PersonId
FROM tblPeople s, Numbers n
WHERE n.number <= s.NumTickets
Following Stored procedure will serve your purpose...
DELIMITER $$
USE <your database name> $$
DROP PROCEDURE IF EXISTS `update_ticket_value2`$$
CREATE PROCEDURE `update_ticket_value2`()
BEGIN
DECLARE index_value INT;
DECLARE loop_variable INT;
SET #KeyValue = 100;
SET #LastPersonID = 0;
SET #TicketNum = 0;
SET #PersonIDToHandle = 0;
SELECT #PersonIDToHandle = PersonID, #TicketNum = NumTickets
FROM tblPeople
WHERE PersonId > #LastPersonID
ORDER BY PersonId
LIMIT 0,1;
WHILE #PersonIDToHandle IS NOT NULL
DO
SET loop_variable = 0;
WHILE(loop_variable < #TicketNum) DO
INSERT INTO tblTickets(TicketId, PersonId) VALUES(#KeyValue + loop_variable, #PersonIDToHandle);
SET loop_variable = loop_variable + 1;
END WHILE;
SET #LastPersonID = #PersonIDToHandle;
SET #PersonIDToHandle = NULL;
SET #KeyValue = #KeyValue + #TicketNum;
SELECT #PersonIDToHandle := PersonID, #TicketNum := NumTickets
FROM tblPeople
WHERE PersonId > #LastPersonID
ORDER BY PersonId
LIMIT 0,1;
END WHILE;
END$$
DELIMITER ;
Call the procedure as:
CALL update_ticket_value2();
Hope it helps...