I wrote a function to generate unique id's,its working but sometimes two people are getting same id,I mean duplicates are formed. My unique id looks like
2016-17NLR250001, I deal with only last four digits 0001. I am posting my function please correct it and please help me in avoiding duplicates even though users login into same account or if they do it on same time.
MY FUNCTION:
DELIMITER $$
USE `olmsap`$$
DROP FUNCTION IF EXISTS `fun_generate_uniqueid`$$
CREATE DEFINER=`root`#`%` FUNCTION `fun_generate_uniqueid`( V_DATE DATE,V_MANDALID INT ) RETURNS VARCHAR(30) CHARSET latin1
DETERMINISTIC
BEGIN
DECLARE MDLCODE VARCHAR(5);
SET MDLCODE = ' ';
SELECT COUNT(*) INTO #CNT FROM `st_com_mandal` WHERE MANDAL_VS_MC=V_MANDALID;
SELECT dist_mandal_code INTO MDLCODE FROM `st_com_mandal` WHERE MANDAL_VS_MC=V_MANDALID;
IF #CNT>0 THEN
SET #YR=`FUN_FISCAL_YR`(V_DATE);
SELECT CONCAT(IF(DIST_SAN_CODE='GUN','GNT',DIST_SAN_CODE),IFNULL(`dist_mandal_code`,'NULL'))INTO #MANDAL
FROM `st_com_dist` SCD INNER JOIN `st_com_mandal` STM ON STM.`mandal_dist_id`= SCD.`DIST_VC_DC` WHERE MANDAL_VS_MC=V_MANDALID;
IF MDLCODE >0 THEN
SELECT COUNT(Soil_Sample_ID)+1 INTO #ID FROM `tt_mao_soil_sample_dtls` WHERE MANDAL_ID=V_MANDALID AND SUBSTR(UNIQUE_ID,1,7)=#YR ;
ELSE
SELECT COUNT(Soil_Sample_ID)+1 INTO #ID FROM `tt_mao_soil_sample_dtls` WHERE SUBSTR(UNIQUE_ID,1,14)=CONCAT(#YR,#MANDAL) ;
END IF ;
IF LENGTH(#ID)=1 THEN
SET #ID=CONCAT('000',#ID);
ELSEIF LENGTH(#ID)=2 THEN
SET #ID=CONCAT('00',#ID);
ELSEIF LENGTH(#ID)=3 THEN
SET #ID=CONCAT('0',#ID);
ELSE
SET #ID=#ID;
END IF ;
RETURN CONCAT(#YR,#MANDAL,#ID);
ELSE
RETURN 'Mandal Doesnt Exists';
END IF;
END$$
DELIMITER ;
I do not think community will be able to help you with this question. This is a complex function that requires very careful analysis of table / index access and locking.
The only thing I can recommend is to not use existing table data to calculate next sequence as this is a bad practice.
Besides Race conditions that you are experiencing you will also get problems if the record with the last sequence is deleted.
I suggest you read this to get an idea on how to write a custom sequence generator:
http://en.latindevelopers.com/ivancp/2012/custom-auto-increment-values/
Related
I am trying to use an attribute from a 2nd table in the trigger of the 1st. To do this I am trying to load that value into a variable and then use it as a comparison.
However whenever I try and test the process the comparison answers false.
DELIMITER $$
create trigger evolve_persona before update on phantom_thieves
for each row begin
set #t := (select tier from persona where pname = old.persona);
if((new.persona != old.persona) and (select cast(#t as unsigned) = '1')) then
set
new.st = old.st+10, new.ma = old.ma+10, new.en= old.en+10, new.ag= old.ag+10,
new.lu= old.lu+20;
end if;
end$$
DELIMITER ;
I can see nothing wrong with your trigger but, this is somewhat more complicated as be written in a comment.
Make please following
SET #t = -1;
SELECT #t; -- returns -1
update phantom_thieves SET .....
SELECT #t; -should display at sometime 1
This seems to be the only problem that tier don't has the response 1 and with above, you can see what you get.
I have a Mysql table name xyz which has two columns tc_name and tc_path where tc_path is like /a/b/c/x/tc_name and tc_name is null .I want to insert the values in the column(tc_name) using this tc_path column values.
I know it would be something like we do with regular expressions in other languages.But i have no idea how to do this in Mysql.
I source the function:
DELIMITER $$
CREATE FUNCTION `regex_replace`(pattern VARCHAR(1000),replacement VARCHAR(1000),original VARCHAR(1000))
RETURNS VARCHAR(1000)
DETERMINISTIC
BEGIN
DECLARE temp VARCHAR(1000);
DECLARE ch VARCHAR(1);
DECLARE i INT;
SET i = 1;
SET temp = '';
IF original REGEXP pattern THEN
loop_label: LOOP
IF i>CHAR_LENGTH(original) THEN
LEAVE loop_label;
END IF;
SET ch = SUBSTRING(original,i,1);
IF NOT ch REGEXP pattern THEN
SET temp = CONCAT(temp,ch);
ELSE
SET temp = CONCAT(temp,replacement);
END IF;
SET i=i+1;
END LOOP;
ELSE
SET temp = original;
END IF;
RETURN temp;
END$$
I tried this:
update testplans set tc_name=regex_replace('.*/','',tc_path);
It should have given me tc_name=d if tc_path=/a/b/c/d
But instead it gave me abcd.
Am i using a wrong function or i don't know how to use it.
Please suggest some query for it.
Please help!!!
Thanks
In THIS particular case, where you are trying to get the last part of a path, you can skip regex and use simple string functions:
update testplans set tc_name=substr(tc_path, length(tc_path)-locate('/',reverse(tc_path))+2);
Doing search in reverse order
The proper regex expression would be
.*/([^/]*)
But you'd need to extract the last part, which MySQL really doesn't do. MariaDB 10 has a REGEXP_REPLACE that might help.
The function you have above will replace single characters that match a regex, but it's not a full regular expression replacement. Basically, wrong function.
Mysql isn't great at this right now -- you might want to consider another path, like the one that Jacques suggested, with a simple string replace.
If you really want a regex solution, maybe look at a more complete regex library for mysql:
https://github.com/mysqludf/lib_mysqludf_preg
We have a monitor on our databases to check for ids approaching max-int or max-bigint. We just moved from MySQL, and I'm struggling to get a similar check working on PostgreSQL. I'm hoping someone can help.
Here's the query in MySQL
SELECT table_name, auto_increment FROM information_schema.tables WHERE table_schema = DATABASE();
I'm trying to get the same results from PostgreSQL. We found a way to do this with a bunch of calls to the database, checking each table individually.
I'd like to make just 1 call to the database. Here's what I have so far:
CREATE OR REPLACE FUNCTION getAllSeqId() RETURNS SETOF record AS
$body$
DECLARE
sequence_name varchar(255);
BEGIN
FOR sequence_name in SELECT relname FROM pg_class WHERE (relkind = 'S')
LOOP
RETURN QUERY EXECUTE 'SELECT last_value FROM ' || sequence_name;
END LOOP;
RETURN;
END
$body$
LANGUAGE 'plpgsql';
SELECT last_value from getAllSeqId() as(last_value bigint);
However, I need to somehow add the sequence_name to each record so that I get output in records of [table_name, last_value] or [sequence_name, last_value].
So I'd like to call my function something like this:
SELECT sequence_name, last_value from getAllSeqId() as(sequence_name varchar(255), last_value bigint);
How can I do this?
EDIT: In ruby, this creates the output we're looking for. As you can see, we're doing 1 call to get all the indexes, then 1 call per index to get the last value. Gotta be a better way.
def perform
find_auto_inc_tables.each do |auto_inc_table|
check_limit(auto_inc_table, find_curr_auto_inc_id(auto_inc_table))
end
end
def find_curr_auto_inc_id(table_name)
ActiveRecord::Base.connection.execute("SELECT last_value FROM #{table_name}").first["last_value"].to_i
end
def find_auto_inc_tables
ActiveRecord::Base.connection.execute(
"SELECT c.relname " +
"FROM pg_class c " +
"WHERE c.relkind = 'S'").map { |i| i["relname"] }
end
Your function seems quite close already. You'd want to modify it a bit to:
include the sequences names as literals
returns a TABLE(...) with typed columns instead of SET OF RECORD because it's easier for the caller
Here's a revised version:
CREATE OR REPLACE FUNCTION getAllSeqId() RETURNS TABLE(seqname text,val bigint) AS
$body$
DECLARE
sequence_name varchar(255);
BEGIN
FOR sequence_name in SELECT relname FROM pg_class WHERE (relkind = 'S')
LOOP
RETURN QUERY EXECUTE 'SELECT ' || quote_literal(sequence_name) || '::text,last_value FROM ' || quote_ident(sequence_name);
END LOOP;
RETURN;
END
$body$
LANGUAGE 'plpgsql';
Note that currval() is not an option since it errors out when the sequence has not been set in the same session (by calling nextval(), not sure if there's any other way).
Would something as simple as this work?
SELECT currval(sequence_name) from information_schema.sequences;
If you have sequences that aren't keys, I guess you could use PG's sequence name generation pattern to try to restrict it.
SELECT currval(sequence_name) from information_schema.sequences
WHERE sequence_name LIKE '%_seq';
If that is still too many false positives, you can get table names from the information_schema (or the pg_* schemata that I don't know very well) and refine the LIKE parameter.
I'm fairly new to SQL in general and even more so to MySQL and I've hit a stumbling block. I'm attempting to use a procedure to copy the value of one field to another if the original field is not null, this procedure is then called by triggers whenever the table is updated or has a new row inserted into it. Here is what I have so far:
-- WORK_NOTES_PROCEDURE - This copies the contents of the estimate notes to the work order notes if the original estimate had any notes with it.
DROP PROCEDURE IF EXISTS 'WORK_NOTES_PROCEDURE';
DELIMITER $$
CREATE PROCEDURE WORK_NOTES_PROCEDURE()
BEGIN
DECLARE var_temp VARCHAR(50);
SET var_temp := (SELECT ESTIMATE_NOTES FROM ESTIMATES WHERE ESTIMATES.ESTIMATE_NUMBER = WORK_ORDERS.ESTIMATE_NUMBER);
IF var_temp IS NOT NULL THEN
UPDATE WORK_ORDERS SET WORK_ORDER_NOTES = var_temp WHERE WORK_ORDERS.ESTIMATE NUMBER = ESTIMATES.ESTIMATE_NUMBER;
END IF;
END$$
DELIMITER ;
Absolutely any help would be appreciated, the error I'm getting is a syntax error for the line where I'm assigning a value to var_temp.
try,
SET var_temp = (SELECT ESTIMATE_NOTES
FROM ESTIMATES INNER JOIN WORK_ORDERS
ON ESTIMATES.ESTIMATE_NUMBER = WORK_ORDERS.ESTIMATE_NUMBER
LIMIT 1);
I'm writing a stored procedure that uses multiple IF / THEN statements that also need to execute multiple queries if they evaluate to true. Problem is, I can't seem to find any examples of the appropriate syntax. From the MySQL dev handbook, it seems like I could have multiple queries in the "statement_list," but so far I can't get it to work.
Here's what I'm trying to do:
SET agency =
COALESCE((SELECT org_agency_o_id
FROM orgs_agencies
WHERE org_agency_code = maj_agency_cat)
,(SELECT min(org_id)
FROM orgs
WHERE org_name LIKE CONCAT('U.S.',SUBSTRING(maj_agency_cat,5))))
IF agency IS NULL THEN
-- execute multiple queries
INSERT INTO orgs (org_name
,org_name_length
,org_type
,org_sub_types)
VALUES (CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5))
,LENGTH(CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5)))
,'org','Org,GovernmentEntity,Federal,Agency');
SET agency = LAST_INSERT_ID();
END IF;
The error:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF agency IS NULL THEN
INSERT INTO orgs (org_name,org_name_length,org_type,' at line 53
Any ideas? I know it has to be something simple, so I would greatly appreciate anybody's input.
You got a few issues as far as I can see:
As David pointed out, each and every statement needs to be terminated by a ;
If you do a SELECT, better make sure it can only select one value by doing a LIMIT 1; If you've got an aggregate function like min() then only one value can come out.
If you writing the procedure using the CREATE PROCEDURE ... syntax, don't forget to set DELIMITER $$ before the CREATE PROCEDURE ... END $$ body and a DELIMITER ; after.
If you have multiple statements inside your IF THEN ... END IF block, it's a good idea to put them inside a BEGIN ... END; block.
If you have a return value, like agency here, why not make it a FUNCTION name (arg1: INTEGER) RETURNS INTEGER instead of a PROCEDURE name (IN arg1 INTEGER, OUT agency INTEGER). The function is much more versatile.
DELIMITER $$
CREATE PROCEDURE name(arg1 INTEGER, arg2 INTEGER, ...)
BEGIN
SELECT SET agency =
COALESCE((SELECT org_agency_o_id
FROM orgs_agencies
WHERE org_agency_code = maj_agency_cat) LIMIT 1,
(SELECT min(org_id) FROM orgs
WHERE org_name LIKE CONCAT('U.S.',SUBSTRING(maj_agency_cat,5))));
IF agency IS NULL THEN BEGIN
-- execute multiple queries
INSERT INTO orgs (org_name
,org_name_length
,org_type
,org_sub_types)
VALUES (CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5))
,LENGTH(CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5)))
,'org','Org,GovernmentEntity,Federal,Agency');
SET agency = LAST_INSERT_ID();
END; END IF;
END $$
DELIMITER ;
No semicolon after your first SET statement.