I am saving documents to database, each document has to have an id with the format YYYY-00000:
the first 4 characters are the current year
the second five characters are numbers. They start with 1 each year and then increment.
For example I could have these documents in my database: 2011-00001, 2011-00002, 2011-00003, 2012-00001, 2012-00002, ...
I am thinking something like this:
add two columns to table Documents (Year and Number)
Year is computed column, something like year(getdate())
Number is computed column, which gets value from a function GetNextNumberForCurrentYear
GetNextNumberForCurrentYear returns next number for the current year (for example select max(Number) + 1 from Documents where Year = year(getdate()), and some isnull checking)
But i fear, that two users could want to save the document at the same time and that they would receive the same Number. Is this possible? Any better ideas?
It is a ASP.NET C# web application, .NET 4.0, MSSQL 2005, I have the control over all the parts of the application.
PS: after insert I would like to return the Id of the new document to the user, so I would probably have to do something like: select Id from Documents where SomeId = scope_identity(), so I guess there should be an identity column somewhere...?
Edit (final solution): I get the next number from stored procedure, build the Id of the document (in format YYYY-00001) in .NET, save the whole document to the database (using TransactionScope for whole process) and then return the Id to the user.
create table DocumentNumbers ([Year] int not null, Number int not null default 1)
insert into DocumentNumbers ([Year], Number)
select 2012, 1 -- and more...
create procedure GetNextDocumentNumber
#year int
as
begin
declare #myResult table (nextNumber int)
update DocumentNumbers
set Number = isnull(Number, 0) + 1
output inserted.Number into #myResult
where [Year] = #year
select top 1 nextNumber from #myResult
end
You could create a table NumberSeries, which contains a column Year and a column CurrentNo and a function that returns the next number from it like the following:
DECLARE #myResult TABLE (nextNumber INT)
UPDATE NumberSeries
OUTPUT INSERTED.NextNo INTO #myResult
SET
CurrentNo = ISNULL(CurrentNo, 0) + 1
WHERE
Year = Year(GetDate())
DECLARE #result INT
#result = (SELECT TOP 1 nextNumber FROM #myResult)
RETURN #result
This updates the NumberSeries table atomically and inserts the new value into the #myResult table variable. After that, it returns the first (and only) value from the #myResult table variable.
Everything else, like SCOPE_IDENTITY() and such may cause errors when using triggers or in other cases - the solution using the OUTPUT clause is safe.
EDIT
As for returning the ID of the inserted document: this is basically the same thing.
DECLARE #myDocId TABLE (yr int, no int)
INSERT INTO Documents
OUTPUT INSERTED.Year , INSERTED.YearID INTO #myDocID
...
SELECT TOP 1
CAST(yr AS NVARCHAR) +
'_' +
RIGHT(REPLICATE('0', 5) + CAST(no AS NVARCHAR), 5) AS NewID
Related
I am trying to write a MariaDB stored procedure.
Due to SQL_SAFE_UPDATES, it is required to use the ID column to use in the WHERE clause for updates. Due to this, what is the normal approach to also select a value from one of the other columns? I do not want to have multiple SELECT statements as it seems inefficient and room for error because they could return values from different rows.
I would like to store my first select statement
SELECT id, sequence FROM RECORDSEQUENCE WHERE SEQTABLE = SeqTable;
In the following two parameters #id, #seq from two seperate columns in the above query and use them in the UPDATE statement as well as the IF statement.
CREATE DEFINER=`sd`#`%` PROCEDURE `SD_GenerateNextRecordSequence`(IN SeqTable int)
BEGIN
SELECT id, sequence FROM RECORDSEQUENCE WHERE SEQTABLE = SeqTable;
IF (#seq IS NOT NULL) THEN
SET #NEXTSEQ := #seq+1;
UPDATE RECORDSEQUENCE SET RECORDSEQUENCE = #NEXTSEQ WHERE id = #id;
ELSE
SET #NEXTSEQ := 100;
INSERT INTO RECORDSEQUENCE (RECORDSEQUENCE,SEQTABLE) VALUES (#NEXTSEQ,SeqTable);
END IF;
SELECT #NEXTSEQ as SEQUENCE;
END
Hello i have an sqlite db with many records like 10540 record they are ordered by creation time , i want to shift like a record in the middle and like to do it automatically
for example :
select * from table1 where id >= 8521;
UPDATE Table1 SET id = id +1 ;
does not work i get Error: Result: UNIQUE constraint failed:
so i want to shift up all records from 8521 to the last record and get place in the 8520 place for example so i can insert my record in that place of table .
even the
id = select max(id)+1
does not work how can i increment the id from last record to the needed record so i can put a place in the records db
A simple update statement would fail, as it would try to create duplicate values in the primary key.
What you can do is this:
First update the column to the negatives of the values they should have:
update table1
set id = -(id + 1)
where id > 8520;
Now there are no duplicates and you just need to update again to the positive values:
update table1
set id = -id
where id < 0;
This will do the trick, but any kind of updating the primary key is not a recommended practice
I have an SQLite database for an art exhibition. In the table "exhibits" I have columns for the artwork ID, the exhibition space ID, a begin date, and an end date. The default value for "end date" is NULL.
Of course, the same artwork cannot be displayed in two different spaces at once. So I want to ensure that a new row with an artwork ID is not created unless all existing rows with that same artwork ID have a non-null end date.
Is there some kind of constraint, trigger, etc. that I can add to the table to ensure this?
I am not an expert on writing triggers for SQLite but something like this should work,
CREATE TRIGGER check_open_ended_exhibit BEFORE INSERT ON exhibits
BEGIN
SELECT RAISE(ABORT, "Open ended exhibit exists")
WHERE EXISTS(SELECT * FROM exhibits WHERE artworkID = NEW.artworkID AND enddate IS NULL);
END
According to your information “Artwork” cannot be displayed twice in the same show which means the EndTime is a unique field when constraining it together with Artwork. So by making these two together your constrain you won’t be able to insert a record if you already have “artwork and NULL”.
So yeah you can just create a unique constrain on these two columns.
CREATE TABLE testConstrain (
id INTEGER NOT NULL,
endDate DATETIME
)
CREATE UNIQUE INDEX testConstrain
ON testConstrain(id, endDate);
INSERT INTO testConstrain VALUES('1',null)
INSERT INTO testConstrain VALUES('2','01-01-2018')
INSERT INTO testConstrain VALUES('1','01-01-2018')
INSERT INTO testConstrain VALUES('1',null)
`
And you will get:
Started executing query at Line 11
(1 row affected)
(1 row affected)
(1 row affected)
Msg 2601, Level 14, State 1, Line 4
Cannot insert duplicate key row in object 'bginsburg.testConstrain' with unique index 'testConstrain'. The duplicate key value is (1, ).
The statement has been terminated.
I want to select Column from Table based on Its Order
like
create Table Products
(
ProductId Int,
ProductName varchar(50)
)
lets Say I don't Know the name of the second column.
How I can get it like :
Select Col1,Col2 From Product
For SQL Server:
You can't do this in the SELECT clause. You can't select based on the order number of the column. You have to list the columns' names you need to select explicitly, otherwise, use SELECT * to list all. Me be if you are using a data reader object or any other ado.net methods to get the data from database you can do something like this, but this will be based on the column names list listed in your SQL statement.
However, you can do something like this dynamically, by reading columns' metadata ordinal_position from information_schema.columns as explained in the following answer:
Is it possible to select sql server data using column ordinal position?
But, you can do this in the ORDER BY clause. You can ORDER BY column number:
SELECT *
FROM TableName
ORDER BY 2; -- for col2
But this is not recommended to use in ORDER BY or in the SELECT (if any). Furthermore, columns order is not significant in the relational model.
Update: If you want to select at least 3 columns from any table parameter passed to your stored procedure. Try this as follows:
Your stored procedure supposed to receive a parameter #tableNameParam. The folowing code should return the first three columns from the #tablenameParam passed to the stored procedure:
DECLARE #col1 AS VARCHAR(100);
DECLARE #col2 AS VARCHAR(100);
DECLARE #col3 AS VARCHAR(100);
DECLARE #tableNameParam AS VARCHAR(50) = 'Tablename';
DECLARE #sql AS VARCHAR(MAX) ;
SELECT #col1 = column_name FROM information_schema.columns
WHERE table_name = #tableNameParam
AND ordinal_position = 1;
SELECT #col2 = column_name FROM information_schema.columns
WHERE table_name = #tableNameParam;
AND ordinal_position = 2;
SELECT #col3 = column_name FROM information_schema.columns
WHERE table_name = #tableNameParam;
AND ordinal_position = 3;
SET #sql = 'SELECT ' + col1 + ',' + col2 ' + 'col3 ' + FROM ' + #tablename;
you always can do
select * from Product
I'd like to share the following code as a solution to CRUD processing on Ordinal Position within a table. I had this problem today and it took me quite a long time to research and find a working solution. Many of the posted answers indicated that it was not possible to interact with the tables columns on an Ordinal bases but as indicated in the post above using the information_schema table will allow using the column position.
My situation was interacting with a table populated through the use of a pivot view so the columns are always changing based on the data, which is fine in a view result but when the dataset is stored into a table the columns are dynamic. The column names are a Year-Month combination such as 201801, 201802 with an Item Number as a primary key. This pivot table is to indicate manufacturing quantities by Year-Month on a rolling 12 month period so each month the column names with change/shift which changes their ordinal position when the table is rebuilt each month.
The Pivot view is used to build the Staging table, The Staging table is used to build the
Target table so the ordinal position of the staging and target tables are lined up with the same ordinal position.
Declare #colname Varchar(55) -- Column Name
Declare #ordpos INT -- Ordinal Position
Declare #Item Varchar(99) -- PK
Declare #i INT -- Counter
Declare #cnt INT -- Count
Declare #ids table(idx int identity(1,1), Item Varchar(25))
-- Item List
Insert INTO #ids Select Item From DBName.Schema.TableName
select #i = min(idx) - 1, #cnt = max(idx) from #ids
-- Row Loop
While #i < #cnt
Begin
Select #i = #i + 1
Set #ordpos=3
Set #Item = (select Item from #ids where idx = #i)
-- Column Loop
While #ordpos < 27
Begin
Select #colname =column_name From INFORMATION_SCHEMA.Columns Where table_name='TargetTable' and ordinal_position=#ordpos
Exec ('Update TargetTable set ['+#colname+']= (Select ['+#colname+'] From StagingTable Where Item='''+#Item+''') where Item='''+#Item+'''')
Set #ordpos=#ordpos + 1
End -- End Column Loop
End -- End Row Loop
The code here will loop through the Item matrix by rows and by columns and uses Dynamic SQL to build the action, in this case the action is an update but it could just as easily be a select. Each column is processed through the While Loop and then loops through the next row. This allows updates to a specific cell in the matrix by (Item X YearMonth) without actually knowing what the column name at a given position.
The one concern is that depending on the size of the data in this matrix it can be SLOW. I just wanted to show this as a way to use unknown column names in an ordinal position.
I have a stored procedure which uses the IN clause. In my ASP.NET application, I have a multiline textbox that supplies values to the stored procedure. I want to be able to order by the values as they were entered in the textbox. I found out how to do this easily in mySQL (using FIELD function), but not a SQL Server equivalent.
So my query looks like:
Select * from myTable where item in #item
So I would be passing in values from my application like '113113','112112','114114' (in an arbitrary order). I want to order the results by that list.
Would a CASE statement be feasible? I wouldn't know how many items are coming in the textbox data.
How are you parameterising the IN clause?
As you are on SQL Server 2008 I would pass in a Table Valued Parameter with two columns item and sort_order and join on that instead. Then you can just add an ORDER BY sort_order onto the end.
From KM's comment above...
I know you didn't state it is comma seperated, but if it was a CSV or even if you have it space seperated you could do the following.
DECLARE #SomeTest varchar(100) --used to hold your values
SET #SomeTest = (SELECT '68,72,103') --just some test data
SELECT
LoginID --change to your column names
FROM
Login --change to your source table name
INNER JOIN
( SELECT
*
FROM fn_IntegerInList(#SomeTest)
) n
ON
n.InListID = Login.LoginID
ORDER BY
n.SortOrder
And then create fn_IntegerInList():
CREATE FUNCTION [dbo].[fn_IntegerInList] (#InListString ntext)
RETURNS #tblINList TABLE (InListID int, SortOrder int)
AS
BEGIN
declare #length int
declare #startpos int
declare #ctr int
declare #val nvarchar(50)
declare #subs nvarchar(50)
declare #sort int
set #sort=1
set #startpos = 1
set #ctr = 1
select #length = datalength(#InListString)
while (#ctr <= #length)
begin
select #val = substring(#InListString,#ctr,1)
if #val = N','
begin
select #subs = substring(#InListString,#startpos,#ctr-#startpos)
insert into #tblINList values (#subs, #sort)
set #startpos = #ctr+1
end
if #ctr = #length
begin
select #subs = substring(#InListString,#startpos,#ctr-#startpos)
insert into #tblINList values (#subs, #sort)
end
set #ctr = #ctr +1
set #sort = #sort + 1
end
RETURN
END
This way your function creates a table that holds a sort order namely, SortOrder and the ID or number you are passing in. You can of course modify this so that you are looking for space rather then , values. Otherwise Martin has the right idea in his answer. Please note in my example I am using one of my tables, so you will need to change the name Login to whatever you are dealing with.
the same way you concatenate ('113113','112112','114114') to pass to the sql sentence in the where clausule you can concatenate
order by
case item
when '113113' then 1
when '112112' then 2
when '114114' then 3
end
to pass to your order by clausule