Using SQL Server 2016, I'm trying to use a sequence to insert values automatically into a column, when another value is not null. However, if the case value is null, the next non-null NEXT VALUE FOR has increased by however many null values precede it. I'm unsure how to prevent this from occurring. The code is below:
The relevant part of the stored proc to create the sequence:
DECLARE #IdMax INT;
SELECT #IdMax = (MAX(CAST(Id AS Int)) + 1) from [db].[dbo].[table] WHERE ISNUMERIC(Id) = 1;
EXEC('CREATE SEQUENCE Id_Sequence
START WITH ' + #IdMax + '
INCREMENT BY 1
CACHE 1000;')
And the rough testing implementation:
DECLARE #StartDate date
SET #StartDate = '20220816'
DECLARE #IDSequenceValue int
SET #IDSequenceValue = CAST(NEXT VALUE FOR Id_Sequence as nvarchar(7))
INSERT INTO dbo.table (
StartDate,
Id)
Values (
#StartDate,
CASE
WHEN #StartDate IS NULL THEN NULL
ELSE #IdSequenceValue
END);
The code has been abridged to remove identifiable information. I had to declare the NEXT VALUE FOR statement as a variable to get around not being able to use it within the Case statement directly. My abridged outputs are:
StartDate Id
2022-08-17 5078561
NULL NULL
NULL NULL
2022-08-17 5078558
2022-08-17 5078557
NULL NULL
2022-08-17 5078555
2022-08-17 5078554
2022-08-17 5078553
Can this issue be overcome? I'm at a loss here. Thanks!
The issue is, you are generating the next sequence number always by this statement :
SET #IDSequenceValue = CAST(NEXT VALUE FOR Id_Sequence as nvarchar(7))
In your CASE expression, you are using the value conditionally. To resolve the issue, I would suggest to generate the next sequence number only if it is required to use like this :
if #StartDate IS NOT NULL
begin
SET #IDSequenceValue = CAST(NEXT VALUE FOR Id_Sequence as nvarchar(7))
end
I have several days trying to solve this problem, but my lack of knowledge is stopping me, I don’t know if is possible what I am trying to accomplish.
I need to have a table like this:
The first field should be a custom primary key ID (auto incremented):
YYYYMMDD-99
Where YYYMMDD is the actual day and “99” is a counter that should be incremented automatically from 01 to 99 in every new row added and need to be automatically restarted to 01 the next day.
The second field is a regular NVARCHAR(40) text field called: Name
For example, I add three rows, just introducing the “Name” of the person, the ID is automatically added:
ID Name
---------------------------
20160629-01 John
20160629-02 Katie
20160629-03 Mark
Then, the next day I add two new rows:
ID Name
-------------------------
20160630-01 Bob
20160630-02 Dave
The last two digits should be restarted, after the day changes.
And, what is all this about ?
Answer: Customer requirement.
If is possible to do it in a stored procedure, it will works for me too.
Thanks in advance!!
This is pretty easy to achieve, but a bit complicated to do so it is safe with multiple clients.
What you need is a new table (for example named IndexHelper) that actually stores the parts of the index as it should be using two columns: One has the current date properly formatted as you want it in your index and one is the current index as integer. Example:
DateString CurrentIndex
-------------------------------
20160629 13
Now you need some code that helps you get the next index value atomically, i.e. in a way that also works when more than one client try to insert at the same time without getting the same index more than once.
T-SQL comes to the rescue with its UPDATE ... OUTPUT clause, which allows you to update a table, at the same time outputting the new values as an atomic operation, which can not be interrupted.
In your case, this statement could look like this:
DECLARE #curDay NVARCHAR(10)
DELCARE #curIndex INT
DECLARE #tempTable TABLE (theDay NVARCHAR(10), theIndex INT)
UPDATE IndexHelper SET CurrentIndex = CurrentIndex + 1 OUTPUT INSERTED.DateString, INSERTED.CurrentIndex INTO #temptable WHERE CurrentDate = <code that converts CURRENT_TIMESTAMP into the string format you want>
SELECT #curDay = theDay, #curIndex = theIndex FROM #tempTable
Unfortunately you have to go the temporary table way, as it is demanded by the OUTPUT clause.
This increments the CurrentIndex field in IndexHelper atomically for the current date. You can combine both into a value like this:
DECLARE #newIndexValue NVARCHAR(15)
SET #newIndexValue = #curDay + '-' + RIGHT('00' + CONVERT(NVARCHAR, #curIndex), 2)
Now the question is: How do you handle the "go back to 01 for the next day" requirement? Also easy: Add entries into IndexHelper for 2 days in advance with the respective date and index 0. You can do this safely everytime your code is called if you check that an entry for a day is actually missing. So for today your table might look like this:
DateString CurrentIndex
-------------------------------
20160629 13
20160630 0
20160701 0
The first call tomorrow would make this look like:
DateString CurrentIndex
-------------------------------
20160629 13
20160630 1
20160701 0
20160702 0
Wrap this up into a stored procedure that does the entire INSERT process into your original table, what you get is:
Add missing entries for the next two days to IndexHelper table.
Get the next ID atomically as described above
Combine date string and ID from the UPDATE command into a single string
Use this in the INSERT command for your actual data
This results in the following stored procedure you can use to insert your data:
-- This is our "work date"
DECLARE #now DATETIME = CURRENT_DATETIME
-- These are the date strings that we need
DECLARE #today NVARCHAR(10) = CONVERT(NVARCHAR, #now, 112)
DECLARE #tomorrow NVARCHAR(10) = CONVERT(NVARCHAR, DATEADD(dd, 1, #now), 112)
DECLARE #datomorrow NVARCHAR(10) = CONVERT(NVARCHAR, DATEADD(dd, 2, #now), 112)
-- We will need these later
DECLARE #curDay NVARCHAR(10)
DELCARE #curIndex INT
DECLARE #tempTable TABLE (theDay NVARCHAR(10), theIndex INT)
DECLARE #newIndexValue NVARCHAR(15)
-- Add entries for next two days into table
-- NOTE: THIS IS NOT ATOMIC! SUPPOSED YOU HAVE A PK ON DATESTRING, THIS
-- MAY EVEN FAIL! THAT'S WHY IS USE BEGIN TRY
BEGIN TRY
IF NOT EXISTS (SELECT 1 FROM IndexHelper WHERE DateString = #tomorrow)
INSERT INTO IndexHelper (#tomorrow, 0)
END TRY
BEGIN CATCH
PRINT 'hmpf'
END CATCH
BEGIN TRY
IF NOT EXISTS (SELECT 1 FROM IndexHelper WHERE DateString = #datomorrow)
INSERT INTO IndexHelper (#datomorrow, 0)
END TRY
BEGIN CATCH
PRINT 'hmpf again'
END CATCH
-- Now perform the atomic update
UPDATE IndexHelper
SET
CurrentIndex = CurrentIndex + 1
OUTPUT
INSERTED.DateString,
INSERTED.CurrentIndex
INTO #temptable
WHERE CurrentDate = #today
-- Get the values after the update
SELECT #curDay = theDay, #curIndex = theIndex FROM #tempTable
-- Combine these into the new index value
SET #newIndexValue = #curDay + '-' + RIGHT('00' + CONVERT(NVARCHAR, #curIndex), 2)
-- PERFORM THE INSERT HERE!!
...
One way to achieve customised auto increment is using INSTEAD OF trigger in SQL Server.
https://msdn.microsoft.com/en-IN/library/ms189799.aspx
I have tested this using below code.
This might be helpful.
It is written with the assumption that maximum 99 records will be inserted in a given day.
You will have to modify it to handle more than 99 records.
CREATE TABLE dbo.CustomerTb(
ID VARCHAR(50),
Name VARCHAR(50)
)
GO
CREATE TRIGGER dbo.InsertCustomerTrigger ON dbo.CustomerTb INSTEAD OF INSERT
AS
BEGIN
DECLARE #MaxID SMALLINT=0;
SELECT #MaxID=ISNULL(MAX(RIGHT(ID,2)),0)
FROM dbo.CustomerTb
WHERE LEFT(ID,8)=FORMAT(GETDATE(),'yyyyMMdd');
INSERT INTO dbo.CustomerTb(
ID,
Name
)
SELECT FORMAT(GETDATE(),'yyyyMMdd')+'-'+RIGHT('00'+CONVERT(VARCHAR(5),ROW_NUMBER() OVER(ORDER BY Name)+#MaxID),2),
Name
FROM inserted;
END
GO
TEST CASE 1
INSERT INTO dbo.CustomerTb(NAME) VALUES('A'),('B');
SELECT * FROM dbo.CustomerTb;
TEST CASE 2
INSERT INTO dbo.CustomerTb(NAME) VALUES('P'),('Q');
SELECT * FROM dbo.CustomerTb;
I am asked to generate custom ID values for primary key columns. The query is as follows,
SELECT * FROM SC_TD_GoodsInward WHERE EntityId = #EntityId
SELECT #GoodsInwardId=IIF((SELECT COUNT(*) FROM SC_TD_GoodsInward)>0, (Select 'GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)+'_'+CONVERT(varchar,#EntityId)+'_'+(SELECT RIGHT('0000'+CONVERT(VARCHAR,CONVERT(INT,RIGHT(MAX(GoodsInwardId),4))+1),4) from SC_TD_GoodsInward)), (SELECT 'GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)+'_'+CONVERT(varchar,#EntityId)+'_0001'))
Here the SC_TD_GoodsInward is a table, GoodsInwardId is the value to be generated. I am getting the desired outputs too. Examples.
GI_131118_1_0001
GI_131212_1_0002
GI_131212_1_0003
But, the above condition fails when the last digits reach 9999. I simulated the query and the results were,
GI_131226_1_9997
GI_140102_1_9998
GI_140102_1_9999
GI_140102_1_0000
GI_140102_1_0000
GI_140102_1_0000
GI_140102_1_0000
GI_140102_1_0000
After 9999, it goes to 0000 and does not increment thereafter. So, in the future, I will eventually run into a PK duplicate error. How can i recycle the values so that after 9999, it goes on as 0000, 0001 ... etc. What am I missing in the above query?
NOTE: Please consider the #EntityId value to be 1 in the query.
I am using SQL SERVER 2012.
Before giving a solution for the question few points on your question:
As the Custom primary key consists of mainly three parts Date(140102), physical location where transaction takes place (entityID), 4 place number(9999).
According to the design on a single date in a single physical location there cannot be more than 9999 transactions -- My Solution will also contain the same limitation.
Some points on my solution
The 4 place digit is tied up to the date which means for a new date the count starts from 0000. For Example
GI_140102_1_0001,
GI_140102_1_0002,
GI_140102_1_0003,
GI_140103_1_0000,
GI_140104_1_0000
Any way the this field will be unique.
The solution compares the latest date in the record to the current date.
The Logic:
If current date and latest date in the record matches
Then it increments 4 place digit by the value by 1
If the current date and the latest date in the record does not matched
The it sets the 4 place digit by the value 0000.
The Solution: (Below code gives out the value which will be the next GoodsInwardId, Use it as per requirement to fit in to your solution)
declare #previous nvarchar(30);
declare #today nvarchar(30);
declare #newID nvarchar(30);
select #previous=substring(max(GoodsInwardId),4,6) from SC_TD_GoodsInward;
Select #today=RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)
+RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2);
if #previous=#today
BEGIN
Select #newID='GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)
+RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)
+'_'+CONVERT(varchar,1)+'_'+(SELECT RIGHT('0000'+
CONVERT(VARCHAR,CONVERT(INT,RIGHT(MAX(GoodsInwardId),4))+1),4)
from SC_TD_GoodsInward);
END
else
BEGIN
SET #newID='GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)
+RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)
+'_'+CONVERT(varchar,1)+'_0000';
END
select #newID;
T-SQL to create the required structure (Probable Guess)
For the table:
CREATE TABLE [dbo].[SC_TD_GoodsInward](
[EntityId] [int] NULL,
[GoodsInwardId] [nvarchar](30) NULL
)
Sample records for the table:
insert into dbo.SC_TD_GoodsInward values(1,'GI_140102_1_0000');
insert into dbo.SC_TD_GoodsInward values(1,'GI_140101_1_9999');
insert into dbo.SC_TD_GoodsInward values(1,'GI_140101_1_0001');
**Its a probable solution in your situation although the perfect solution would be to have identity column (use reseed if required) and tie it with the current date as a computed column.
You get this problem because once the last 4 digits reach 9999, 9999 will remain the highest number no matter how many rows are inserted, and you are throwing away the most significant digit(s).
I would remodel this to track the last used INT portion value of GoodsInwardId in a separate counter table (as an INTEGER), and then MODULUS (%) this by 10000 if need be. If there are concurrent calls to the PK generator, remember to lock the counter table row.
Also, even if you kept all the digits (e.g. in another field), note that ordering a CHAR is as follows
1
11
2
22
3
and then applying MAX() will return 3, not 22.
Edit - Clarification of counter table alternative
The counter table would look something like this:
CREATE TABLE PK_Counters
(
TableName NVARCHAR(100) PRIMARY KEY,
LastValue INT
);
(Your #EntityID might be another candidate for the counter PK column.)
You then increment and fetch the applicable counter on each call to your custom PK Key generation PROC:
UPDATE PK_Counters
SET LastValue = LastValue + 1
WHERE TableName = 'SC_TD_GoodsInward';
Select
'GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)
+RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)
+RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)+'_'
+CONVERT(varchar,#EntityId)+'_'
+(SELECT RIGHT('0000'+ CONVERT(NVARCHAR, LastValue % 10000),4)
FROM PK_Counters
WHERE TableName = 'SC_TD_GoodsInward');
You could also modulo the LastValue in the counter table (and not in the query), although I believe there is more information about the number of records inserted by leaving the counter un-modulo-ed.
Fiddle here
Re : Performance - Selecting a single integer value from a small table by its PK and then applying modulo will be significantly quicker than selecting MAX from a SUBSTRING (which would almost certainly be a scan)
DECLARE #entityid INT = 1;
SELECT ('GI_'
+ SUBSTRING(convert(varchar, getdate(), 112),3,6) -- yymmdd today DATE
+ '_' + CAST(#entityid AS VARCHAR(50)) + '_' --#entity parameter
+ CASE MAX(t.GI_id + 1) --take last number + 1
WHEN 10000 THEN
'0000' --reset
ELSE
RIGHT( CAST('0000' AS VARCHAR(4)) +
CAST(MAX(t.GI_id + 1) AS VARCHAR(4))
, 4)
END) PK
FROM
(
SELECT TOP 1
CAST(SUBSTRING(GoodsInwardId,11,1) AS INT) AS GI_entity,
CAST(SUBSTRING(GoodsInwardId,4,6) AS INT) AS GI_date,
CAST(RIGHT(GoodsInwardId,4) AS INT) AS GI_id
FROM SC_TD_GoodsInward
WHERE CAST(SUBSTRING(GoodsInwardId,11,1) AS INT) = #entityid
ORDER BY gi_date DESC, rowTimestamp DESC, gi_id DESC
) AS t
This should take the last GoodInwardId record, ordered by date DESC and take its numeric "id". Then add + 1 to return the NEW id and combine it with today's date and the #entityid you passed. If >9999, start again from 0000.
You need a timestamp type column tho, to order two inserted in the same date + same transaction time. Otherwise you could get duplicates.
I have simplified the answer even more and arrived with the following query.
IF (SELECT COUNT(GoodsInwardId) FROM SC_TD_GoodsInward WHERE EntityId = #EntityId)=0
BEGIN
SELECT #GoodsInwardId= 'GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)+
RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+
RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)+'_'+
CONVERT(varchar,#EntityId)+'_0001'
END
ELSE
BEGIN
SELECT * FROM SC_TD_GoodsInward WHERE EntityId = #EntityId AND CONVERT(varchar,CreatedOn,103) = CONVERT(varchar,GETDATE(),103)
SELECT #GoodsInwardId=IIF(##ROWCOUNT>0,
(Select 'GI_'+
RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)+
RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+
RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)+'_'+
CONVERT(varchar,#EntityId)+'_'+
(SELECT RIGHT('0000'+CONVERT(VARCHAR,CONVERT(INT,RIGHT(MAX(GoodsInwardId),4))+1),4) from SC_TD_GoodsInward WHERE CONVERT(varchar,CreatedOn,103) = CONVERT(varchar,GETDATE(),103))),
(SELECT 'GI_'+RIGHT('00'+CONVERT(varchar,datepart(YY,getdate())),2)+
RIGHT('00'+CONVERT(varchar,datepart(MM,getdate())),2)+
RIGHT('00'+CONVERT(varchar,datepart(DD,getdate())),2)+'_'+
CONVERT(varchar,#EntityId)+'_0001'))
END
select * from SC_TD_GoodsInward
I have this stored function
function GetPrevReading(
#utility int,
#asofdate datetime
) returns decimal(10,5)
This function returns the previous meter reading from the table with the following fieds:
utility - int
date - datetime
reading - numeric(18,4)
When I use select on this table I want to set a date as a parameter and get this from the table:
Utility Previous Reading
(distinct) GetPrevReading(utility from query, #date from parameter)
I want the function GetPrevReading to take parameter 'utility' from the current row.
Is it possible to accompish this with a query or should I make a stored procedure?
For example, this is the table:
Utility Date Reading
1 2013-10-1 105.6
1 2013-11-1 123.72
2 2013-10-1 226.1
2 2013-10-1 238.18
Now, if I set parameter #date to 2013-10-29 I should get this result:
Utility PreviousReading
1 105.6
2 226.1
Here, my function should get #utility=1 and #asofdate='2013-10-29' on the first row and #utility=2 and #asofdate='2013-10-29' on the second one.
Try this out. I fixed some inconsistencies in your data types, and assumed that your last line of sample data really should have had 2013-11-01 as the date. Also, the way that the function is written, it's not getting the previous reading, but the reading on that date.
CREATE TABLE MyTable (
Utility Int,
Date Date,
Reading Decimal(10,5)
);
INSERT INTO MyTable (Utility, Date, Reading)
VALUES
(1,'2013-10-01', 105.60),
(1,'2013-11-01', 123.72),
(2,'2013-10-01', 226.10),
(2,'2013-11-01', 238.18);
CREATE FUNCTION dbo.GetPrevReading(
#utility int,
#asofdate datetime
)
RETURNS Decimal(10,5)
AS
BEGIN
RETURN (
SELECT TOP 1 Reading
FROM MyTable
WHERE Utility = #Utility
AND Date = #asofdate
ORDER BY Date DESC
)
END;
SELECT
Utility
,Date
,dbo.GetPrevReading(Utility, Date)
FROM (
SELECT Utility, Max(Date) Date
FROM MyTable
WHERE Date < '2013-10-29'
GROUP BY Utility
) x;
Am I understanding the question; the function returns for this call
GetPrevReading( 1,2013-10-29)
Returns
1, 105.6
2, 226.1
And you want to join between the function and its results and the underlying table? You can do this in SQL 2005 + using the Apply join
Select
…
From tblUtilityReadings
Cross Apply GetPrevReading(tblUtilityReadings.utility, #date)
Is there a way to combine assigning a value to a variable and Selecting a column in sql. I need to compute and select a column in a table based on the variable. The variable's value changes based on another column in the table.
var #BeginValue
Columns in table : ReducedBy
My initial begin value is stored in #BeginValue. The table has reducedBy which is a factor by which my begin value should be reduced. So when i select, beginvalue for the first recored would be #BeginValue and the #EndValue should be #BeginValue = #BeginValue - reducedBy. It continues like this, as many times as the number of records in my table.
Result set must be like this:
#Begin = 10
Begin End ReducedBy
10 8 2
8 6 2
6 5 1
Is there a way with which i can achieve this without using a cursor or with multiple update statements.
You can't assign in a query that returns a result set. The closest you can get is to store the result in a table variable. Then you can both do computations against that table, and return it as a result set:
-- Store results in table variable
declare #tbl table (id int, col1 int, ...)
insert #tbl
(id, col1, ...)
select id
, col1
, ...
from ... your query here ...
-- Assign variable
select #YourVariable = ... your computation here ...
from #tbl
-- Return result set
select *
from #tbl
If your question is
Can I do..
SELECT #a = field, field2 from table
and get a resultset and set the value of #a?
Then the answer is no, not in a single statement.