I'm trying to generate a primary key for my table, something like this
(simplified version) - the purpose is to have a daily incremented key:
DELIMITER ^
CREATE TABLE `ADDRESS` (
ID INTEGER NOT NULL DEFAULT -1,
NAME VARCHAR(25),
PRIMARY KEY(`ID`))^
CREATE FUNCTION `GETID`()
RETURNS INTEGER
deterministic
BEGIN
declare CURR_DATE DATE;
declare maxid, _year, _month, _day, newid INTEGER;
set CURR_DATE = CURRENT_DATE;
set _year = EXTRACT(YEAR FROM CURR_DATE);
set _mon = EXTRACT(MONTH FROM CURR_DATE);
set _day = EXTRACT(DAY FROM CURR_DATE);
set newid = (_year - (_year/100) * 100) * 10000 + _mon * 100 + _day;
select max(ID) into maxid From `ADDRESS`;
if (maxid is null) then
set maxid = 0;
end if;
if (MAXID / 1000 != newid) then
set MAXID = newid * 1000;
end if;
set MAXID = MAXID + 1;
return MAXID;
END^
CREATE TRIGGER `ADDRESS_ID_TRIGGER` BEFORE INSERT ON `ADDRESS`
FOR EACH ROW
BEGIN
if new.id=-1 then
set new.id = getid();
end if ;
END^
COMMIT^
DELIMITER ;
Generally it works fine, but when I test it with multiple inserts at the same time
it obviously fails (e.g. no dirty reads, the select max will fail for the 2nd insert,
thus it will generate the same id as fro the 1st insert).
Workaround:
Make primary key AUTO_INCREMENT.
Add TIMESTAMP field and use BEFORE INSERT/UPDATE trigget to set CURRENT_TIMESTAMP().
Also you can use ON UPDATE CURRENT_TIMESTAMP option for TIMESTAMP field, value will be updated automatically.
So, ID is ID, and TIMESTAMP field contains date and time.
Related
I am trying to create a procedure in MySQL that insert weeks (for current year) to my week table. But there is a problem because after first row is added for the next one I get an error: number column cannot be null. I am new to MySQL so I will appreciate any help.
CREATE PROCEDURE generateWeeks()
BEGIN
SET #currentYear = YEAR(CURDATE());
SET #nextYear = #currentYear + 1;
SET #startOfCurrentWeek = CURDATE();
WHILE(#currentYear < #nextYear) DO
SET #endOfCurrentWeek = DATE_ADD(#startOfCurrentWeek , INTERVAL 7 DAY);
SET #weekNumber = WEEK(#startOfCurrentWeek, 3) -
WEEK(#startOfCurrentWeek - INTERVAL DAY(#startOfCurrentWeek)-1 DAY, 3) + 1;
INSERT INTO `week` (`number`, `start_date`, `end_date`)
VALUES (#weekNumber, #startOfCurrentWeek, #endOfCurrentWeek);
SET #startOfCurrentWeek = #endOfCurrentWeek + 1;
SET #currentYear = YEAR(#endOfCurrentWeek);
END WHILE;
END //
DELIMITER ;
EDITED:
Table Creation:
CREATE TABLE `week` (
`id` INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
`number` INT(11) NOT NULL,
`start_date` DATE NOT NULL,
`end_date` DATE NOT NULL
)
Why for first while iteration everything is ok (rows is added), but in the next one I get null value in #weekNumber variable ?
The line:
SET #startOfCurrentWeek = #endOfCurrentWeek + 1;
will convert the variable into a integer. Use date_add instead.
Also, instead of using user-defined variables (#endOfCurrentWeek) you better use local variabled (declare v_endOfCurrentWeek date).
I need to write a Stored procedure to insert data in a column( unique constraint) in mysql and first i have to check if column is null then i have to check for duplicate, if not then insert the random generated data.
BEGIN
DECLARE key1 VARCHAR(10);
DECLARE accid varchar(32);
WHILE ( select count(*) from account where customerkey is null)>0 DO
SET key1 = (SELECT LEFT(MD5(UUID()), 7));
WHILE (SELECT count(*) FROM account WHERE customerkey = key1) < 1 DO
SET accid = (select id from account where customerkey is null limit 1);
update account set customerkey = key1 where id = accid;
END WHILE;
END WHILE;
END
One doesn't need a loop or separate variables in the procedure. Based on what you've posted, you should be able to get away with a single update statement:
update account set customerkey = LEFT(MD5(UUID()), 7) where customerkey is null;
Try that and let me know if it does the trick.
As an aside reassurance, yes, UUID() returns unique for each row.
I would like to capture the primary key value of column based on the last inserted record. Below is the table structure:
create table test
(
id varchar(100) not null primary key,
rmain varchar(100),
rpart bigint
);
Stored Procedure:
Delimiter $$
DROP PROCEDURE IF EXISTS insTest$$
Create Procedure insTest()
Begin
Set #rmain := (select trim(concat('DNB', DATE_FORMAT(CURRENT_DATE(), '%y'), DATE_FORMAT(CURRENT_DATE(), '%m'))));
IF ((trim(DATE_FORMAT(CURRENT_DATE(),'%m')) = 01) OR (trim(DATE_FORMAT(CURRENT_DATE(),'%m')) = 1)) THEN
Set #rpart = 1;
END IF;
IF ((trim(DATE_FORMAT(CURRENT_DATE(),'%m')) != 01) OR (trim(DATE_FORMAT(CURRENT_DATE(),'%m')) != 1)) THEN
Set #rpart := (select coalesce(max(rpart),0) from test) + 1;
END IF;
insert into Test (ID, rmain, rpart) values (concat(#rmain,#rpart),#rmain,#rpart);
End$$
DELIMITER ;
Please advice. I checked on last_insert_ID() but it works for primary key column with auto_increment setting only. Thanks in advance...
Why? What if you get select max(id) or if you get select id from tbl1 order by id desc limit 1?
See Transaction In MySQL. Also, set the transaction isolation level to READ COMMITTED
declare last_id INT;
START TRANSACTION;
INSERT INTO tbl1(id,col1,col2) values(1001,'test','test');
SELECT last_id = id FROM tbl1 ORDER BY id DESC LIMIT 1
COMMIT;
INSERT INTO test (a,b,c) values (1,2,3);
SELECT LAST_INSERT_ID();
this way you can access the last inserted id
I saw another post explaining the use of sequence table to create prefixed AUTO INCREMENT ID.
Link to referenced post
SQL Fiddle
http://sqlfiddle.com/#!2/0ed88/1
I need the generated auto increment format to be: YYMM + AUTO INCREMENT VALUE that reset every month. For example now is January, 2015. The generated id should be: 15011, 15012, 15013, etc. Next month February 2015, the generated id should be: 15021, 15022, 15023, etc. I can use the above method to generate the prefix, however how do I reset the AUTO INCREMENT value each month? Database is InnoDB. Any help will be greatly appreciated :)
MODIFIED CODE
CREATE TABLE table1_seq
(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
)|
CREATE TABLE Table1
(
id VARCHAR(7) NOT NULL PRIMARY KEY DEFAULT '0', name VARCHAR(30)
)|
CREATE TRIGGER tg_table1_insert
BEFORE INSERT ON table1
FOR EACH ROW
BEGIN
INSERT INTO table1_seq VALUES (NULL);
SET NEW.id = CONCAT(DATE_FORMAT(NOW(),'%y%m'), LAST_INSERT_ID());
END |
INSERT INTO Table1 (name) VALUES ('Jhon'), ('Mark')|
If you have a field DATE or DATETIME in your table then this solution maybe can help you.
Let say your table name my_table and has PK id (INT) and also a field bila (DATE). I just need to get last (biggest) id in current month from my_table then add by 1.
SET #mos= (SELECT MAX(id) FROM my_table WHERE MONTH(`bila`) = MONTH(NOW()) AND YEAR(`bila`) = YEAR(NOW()));
SET #mos = IF(
#mos IS NULL,
CONCAT(YEAR(NOW()),MONTH(NOW()),'001'),
#mos + 1
);
Then u can use #mos in your query next
To reset the AUTO_INCREMENT value, drop and recreate the table1_seq table. Given your example, a TRUNCATE statement would be sufficient (given that there aren't any foreign keys, and we assume the table is using either the MyISAM or InnoDB engine).
TRUNCATE TABLE table1_seq ;
(MySQL behavior for this statement is to create a new, empty table, with the AUTO_INCREMENT set back to the value when the table was created.)
This effectively achieves the same result as a DROP table followed by CREATE table.
That answers the question you asked. As a side note, generating a key value this way usually turns out to be a bad idea.
i've relied on the last answer above, i've used the orderDate field from my table and compared it with the current date during insertion , to decide finally if i want to reset or increment the purchaseOrderRef field:
The aim is to insert custom auto increment order id (field name: "purchaseOrderRef" ) with the format DD-MM-XXX in table [Products_SumOrders]. such that it resets the XXX to 0 automatically every month:
USE [Mydatabase] -- here you need to use your own database
GO
/****** Object: Trigger [dbo].[customAutoIncrement] Script Date: 10/1/2016 10:07:41 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TRIGGER [dbo].[customAutoIncrement]
ON [dbo].[Products_SumOrders]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
declare #maxOrderID int;
declare #maxOrderRef nvarchar(max);
declare #relativeID varchar(max);
declare #orderId int;
select #orderId =orderid from inserted;
print(#orderId);--allow me to display the inserted order id
SET #maxOrderID = (SELECT Max(orderid) FROM [Products_SumOrders] WHERE MONTH([OrderDate]) = (MONTH(GETDATE())) AND YEAR([OrderDate]) = YEAR(GETDATE()) and orderid < #orderId );
print(#maxOrderID);--last added order
--custom month format (always MM):
declare #mon int;
declare #stringMon nvarchar(10);
set #mon= MONTH(GETDATE());
IF #mon <10
set #stringMon ='0' + CONVERT(VARCHAR(1),#mon) ;
ELSE
set #stringMon = CONVERT(VARCHAR(2),#mon) ;
IF #maxOrderID is null --no orders has been added in this month:
begin
set #maxOrderRef = Substring(CONVERT(VARCHAR(4),YEAR(GETDATE())),3,4)+ '-'+ CONVERT(VARCHAR(2),#stringMon)+'-001';
end
ELSE
--custom order id format (always XXX):
begin
set #relativeID =(SELECT [purchaseOrderRef] FROM [Products_SumOrders] WHERE orderid=#maxOrderID);
set #relativeID = Substring(#relativeID,LEN(#relativeID)-(Charindex('-', REVERSE(#relativeID))-2),LEN(#relativeID));
print(CONVERT(int,#relativeID));
IF CONVERT(int,#relativeID) < 9
set #relativeID ='00' + CONVERT(VARCHAR(2),#relativeID+1) ;
ELSE
begin
if CONVERT(int,#relativeID) < 99
set #relativeID ='0' + CONVERT(VARCHAR(3),#relativeID+1) ;
else
set #relativeID = CONVERT(VARCHAR(3),#relativeID+1) ;
end
set #maxOrderRef = Substring(CONVERT(VARCHAR(4),YEAR(GETDATE())),3,4)+ '-'+ CONVERT(VARCHAR(2),#stringMon)+'-'+ CONVERT(VARCHAR(3),#relativeID);
end
print(#maxOrderRef);
UPDATE Products_SumOrders
SET purchaseOrderRef = #maxOrderRef
FROM inserted INNER JOIN [Products_SumOrders] On inserted.orderid = [Products_SumOrders].orderid
END
GO
I have a table which contains header information for transactions. The transactions belong to different projects.
In the header I have columns:
rhguid - uniqueidentifier
rhserial - int
rh_projectID - int
First I insert the row (there's more columns)
Then I calculate the serial number for that project:
update responseheader
set rhSerial = 1 + (select isnull(max(rhSerial), 0)
from responseheader
where (rhstatus = 0) AND (rh_projectID = 1234))
where
(rhGUID = <preassignedGUID>);
However when there are many transactions happening at the same time for a project I am finding duplicate rhserial values.
I'm doing this in classic ASP with SQL Server 2008.
Is there a better way?
From your example, it doesn't look like you're using a transaction. My guess is that the SELECT portion of the statement is running as READ UNCOMMITTED, otherwise you would not see duplicates. There are ways to start transactions with ADO, but I prefer using stored procedures instead.
Try implementing something like this:
CREATE PROC dbo.ResponseHeader_Insert
<more data to insert>,
#ProjectID INT,
#Status SMALLINT
as
insert responseheader (column names here)
select <param values here>, isnull(max(rhSerial), 0) + 1
from responseheader
where (rhstatus = #Status) AND (rh_projectID = #ProjectID))
If this doesn't work for ya, try creating sequence tables (one for each sequence).
create table <tablename> (
SeqID int identity(1,1) primary key,
SeqVal varchar(1)
)
Create a procedure to get the next identity:
create procedure GetNewSeqVal_<tablename>
as
begin
declare #NewSeqValue int
set NOCOUNT ON
insert into <tablename> (SeqVal) values ('a')
set #NewSeqValue = scope_identity()
delete from <tablename> WITH (READPAST)
return #NewSeqValue
end
If there are too many sequence tables that need to be created or you want to create sequences on the fly, try this approach:
Create table AllSequences (
SeqName nvarchar(255) primary key, -- name of the sequence
Seed int not null default(1), -- seed value
Incr int not null default(1), -- incremental
Currval int
)
Go
create procedure usp_CreateNewSeq
#SeqName nvarchar(255),
#seed int = 0,
#incr int = 1
as
begin
declare #currval int
if exists (
select 1 from AllSequences
where SeqName = #SeqName )
begin
print 'Sequence already exists.'
return 1
end
if #seed is null set #seed = 1
if #incr is null set #incr = 1
set #currval = #seed
insert into AllSequences (SeqName, Seed, Incr, CurrVal)
values (#SeqName, #Seed, #Incr, #CurrVal)
end
go
create procedure usp_GetNewSeqVal
#SeqName nvarchar(255)
as
begin
declare #NewSeqVal int
set NOCOUNT ON
update AllSequences
set #NewSeqVal = CurrVal = CurrVal+Incr
where SeqName = #SeqName
if ##rowcount = 0 begin
print 'Sequence does not exist'
return
end
return #NewSeqVal
end
go