ignoring last value if its the same as current value - sql

I have an table where i would like to query the following:
The data comes in batches . This data is combined with an id.
This ID only gets send ones when the new batch comes in. After that the ID only changes when there is a new batch . In the mean time the value stays null
What i need to do is if new data comes in and it has the same id as the previous batch i have to continue the insert with null in the id field instead of pushing a new row with the same id value.
Beneath is a simplistic view of the table
ID Values
1 10
null 20
null 20
null 20
null 20
2 20
null 20
null 20
null 20
null 20
1 20
null 20
If you could help me point in a directions that would help me a lot.
Maybe to clearify the id value is a set of tags. So there are some definied tags(100 or more) and when a new batch comes the batch gets a tag with it. And if that tag is the same as the previous the null has to continue instead of inserting the same tag

You'll need to add an identity field (or a timestamp) in order to be able to query the latest ID.
ALTER TABLE MyTable ADD MyIdent INT IDENTITY(1, 1) NOT NULL
Then on your insert (if your Id value is NULL) you can call
INSERT INTO MyTable (Id, Values)
SELECT TOP 1 Id, #ValuesVariable
FROM MyTable
WHERE Id IS NOT NULL
ORDER BY MyIdent DESC

This below Sp may helps to inert data try this
IF OBJECT_ID('tempdb..#Temp')IS NOT NULL
DROP TABLE #Temp
CREATE TABLE #Temp (ID INT,[Values] INT)
CREATE PROCEDURE usp_Insert
(
#Id INT,
#Values INT
)
AS
BEGIN
IF NOT EXISTS (SELECT 1 FROM #Temp WHERE ID = #ID)
BEGIN
INSERT INTO #Temp(ID,[Values])
SELECT #Id,#Values
END
ELSE
INSERT INTO #Temp(ID,[Values])
SELECT NULL,#Values
END
EXEC usp_Insert 2,12
SELECT * FROM #Temp

Related

SQL Server trigger if update() with condition

I have a table in SQL Server that has 3 columns: ID, NAME, VALUE.
This table has 2 rows with ID=1 and ID=2.
(The value of ID doesn't change).
Every moment of time the value of column VALUE changes. Every time the column VALUE changes, I want to insert this updated value into a table (Device1 for ID=1, Device1 for ID=2).
I created a trigger for updating as if update(VALUE) begin...but it doesn't do the work.
Is there a way to add a condition in if update(VALUE) to work in each row
I used this query
Create Trigger insertIntoDevices
On ITEMS
For Update
As
If Update(VALUE)
Begin
Insert Into table device1
Where ID = 1
Insert Into table device2
Where ID = 2
End
With this query each update in column VALUE inserts VALUE into device1 and device1 and that duplicates values in my tables device1 and device2.
Table creation on the below ;
CREATE TABLE TestTable(
ID INT IDENTITY(1,1),
Name VARCHAR(5),
VALUE NVARCHAR(50)
)
GO
CREATE TABLE device1(
VALUE NVARCHAR(50)
)
GO
CREATE TABLE device2(
VALUE NVARCHAR(50)
)
GO
Insertion for ID=1 and ID=2
GO
INSERT INTO TestTable(Name,Value)
VALUES('Test1','test1'),('TEST2','test2')
Firstly,To find new values for each row you can use 'inserted' but it can be include non-changed data. For example: ID =1,Name='test1' and VALUE='test1' and updation of name column will be also included in inserted.
Secondly,To find old values for each row you can use 'deleted'.
After that we find the values that only includes updation for VALUE.
To Sump Up,
Finding Inserted rows and deleted rows will give us the result of each rows new and old values. We used intersection (INNER JOIN ) to find only changed values.
CREATE TRIGGER [dbo].[insertIntoDevices]
ON [dbo].[TestTable]
AFTER UPDATE
AS
BEGIN
DECLARE #InsertedTable table (
InsertedID INT,
InsertedName VARCHAR(5),
InsertedVALUE NVARCHAR(50)
)
DECLARE #DeletedTable table (
DeletedID INT,
DeletedName VARCHAR(5),
DeletedVALUE NVARCHAR(50)
)
INSERT INTO #InsertedTable(InsertedID,InsertedName,InsertedVALUE)
SELECT ID,[Name],[Value] FROM inserted;
INSERT INTO #DeletedTable(DeletedID,DeletedName,DeletedVALUE)
SELECT ID,Name,Value FROM deleted;
INSERT INTO device1(VALUE)
SELECT UpdatedValue = it.InsertedVALUE
FROM #InsertedTable as it
INNER JOIN #DeletedTable as dt ON it.InsertedID = dt.DeletedID AND ISNULL(dt.DeletedVALUE,'') <> ISNULL(it.InsertedVALUE,'')
WHERE it.InsertedID = 1
INSERT INTO device2(VALUE)
SELECT UpdatedValue = it.InsertedVALUE
FROM #InsertedTable as it
INNER JOIN #DeletedTable as dt ON it.InsertedID = dt.DeletedID AND ISNULL(dt.DeletedVALUE,'') <> ISNULL(it.InsertedVALUE,'')
WHERE it.InsertedID = 2
END
To test I used the updation queries on the below;
--Example 1
UPDATE TestTable
SET Value='selam'
WHERE ID = 1
--Example 2
UPDATE TestTable
SET Value='hi'
WHERE ID = 2

Know identity before insert

I want to copy rows from the table within the table itself. But before inserting I need to modify a varchar column appending the value of identity column to it.
My table structure is:
secID docID secName secType secBor
1 5 sec-1 G 9
2 5 sec-2 H 12
3 5 sec-3 G 12
4 7 sec-4 G 12
5 7 sec-5 H 9
If I want to copy data of say docID 5, currently this runs through a loop one row at a time.
I can write my query as
insert into tableA (docID, secName, secType, secBor)
select 8, secName, secType, secBor from tableA where docID = 5
But how can I set value of secName before hand so that it becomes sec-<value of secID column>?
Don't try to guess the value of identity column. In your case you could simply create a computed column secName AS CONCAT('sec-', secID). There is no further need to update that column.
DB Fiddle
It is also possible to create an AFTER INSERT trigger to update the column.
Since SQL Server does not have GENERATED ALWAYS AS ('Sec - ' + id) the only simple option I see is to use a trigger.
Adding to my comment something like:
insert into tableA (docID, secName, secType, secBor)
select
ROW_NUMBER() OVER (ORDER BY DocID),
'Sec -'+ ROW_NUMBER() OVER (ORDER BY DocID),
secType, secBor
from tableA
where docID = 5
In SQL Server 2012 and later, you can achieve this by using the new sequence object.
CREATE SEQUENCE TableAIdentitySeqeunce
START WITH 1
INCREMENT BY 1 ;
GO
create table TableA
(
secId int default (NEXT VALUE FOR TableAIdentitySeqeunce) not null primary key,
varcharCol nvarchar(50)
)
declare #nextId int;
select #nextId = NEXT VALUE FOR TableAIdentitySeqeunce
insert TableA (secId, varcharCol)
values (#nextId, N'Data #' + cast(#nextId as nvarchar(50)))

In a persisted field, how do you return the number of occurrences of a column within a different table's column

The following is required due to records being entered by 3rd parties in a web application.
Certain columns (such as Category) require validation including the one below. I have a table OtherTable with the allowed values.
I need to identify how many occurrences (ie: IF) there are of the current table's column's value in a different table's specified column. If there are no occurrences this results in a flagged error '1', if there are occurrences, then it results in no flagged error '0'.
If `Category` can be found in `OtherTable.ColumnA` then return 0 else 1
How can I do this please?
If Category can be found in OtherTable.ColumnA then return 0 else 1
You could use CASE with EXISTS
SELECT CASE WHEN EXISTS(
SELECT NULL
FROM AllowedValues av
WHERE av.ColumnA = Category
) THEN 0 ELSE 1 END AS ErrorCode
, Category
FROM [Table]
Edit: Here's a sql-fiddle: http://sqlfiddle.com/#!3/55a2e/1
Edit: I've only just noticed that you want to use a computed column. As i've read you can only use it with scalar values and not with sub-queries. But you can create a scalar valued function.
For example:
create table AllowedValues(ColumnA varchar(1));
insert into AllowedValues Values('A');
insert into AllowedValues Values('B');
insert into AllowedValues Values('C');
create table [Table](Category varchar(1));
insert into [Table] Values('A');
insert into [Table] Values('B');
insert into [Table] Values('C');
insert into [Table] Values('D');
insert into [Table] Values('E');
-- create a scalar valued function to return your error-code
CREATE FUNCTION udf_Category_ErrorCode
(
#category VARCHAR(1)
)
RETURNS INT
AS BEGIN
DECLARE #retValue INT
SELECT #retValue =
CASE WHEN EXISTS(
SELECT NULL
FROM AllowedValues av
WHERE av.ColumnA = #category
) THEN 0 ELSE 1 END
RETURN #retValue
END
GO
Now you can add the column as computed column which uses the function to calculate the value:
ALTER TABLE [Table] ADD ErrorCode AS ( dbo.udf_Category_ErrorCode(Category) )
GO
Here's the running SQL: http://sqlfiddle.com/#!3/fc49e/2
Note: as #Damien_The_Unbelieve has commented at the other answer, even if you persist the result with a UDF, the value won't be updated if the rows in OtherTable change. Just keep that in mind, so you need to update the table manually if desired with the help of the UDF.
select mt.*,IFNULL(cat_count.ct,0) as Occurrences from MainTable mt
left outer join (select ColumnA,count(*) as ct from OtherTable) cat_count
on mt.Category=cat_count.ColumnA
Result:
mt.col1 | mt.col2 | Category | Occurrences
### | ### | XXX | 3
### | ### | YYY | 0
### | ### | ZZZ | 1

Loop through rows and add a number for a column for each of them automatically in SQL Server

I have got an over 500 rows table with a column called ID which is of datetype INT. Currently the values are all NULL.
What I want to achieve is to populate the ID column with an incremental number for each row, say 1, 2, 3, 4, ..., 500 etc.
Please give me a help with any idea how to achieve this by SQL script.
using ROW_NUMBER in a CTE is one way, but here's an alternative; Create a new id1 column as int identity(1,1), then copy over to id, then drop id1:
-- sample table
create table myTable(id int, value varchar(100));
-- populate 10 rows with just the value column
insert into myTable(value)
select top 10 'some data'
from sys.messages;
go
-- now populate id with sequential integers
alter table myTable add id1 int identity(1,1)
go
update myTable set id=id1;
go
alter table myTable drop column id1;
go
select * from myTable
Result:
id value
----------- -------------
1 some data
2 some data
3 some data
4 some data
5 some data
6 some data
7 some data
8 some data
9 some data
10 some data
While you could also drop and recreate ID as an identity, it would lose its ordinal position, hence the temporary id1 column.
#create one temporary table
CREATE TABLE Tmp
(
ID int NOT NULL
IDENTITY(1, 1),
field(s) datatype NULL
)
#suppose your old table name is tbl,now pull
#Id will be auto-increment here
#dont select Id here as it is Null
INSERT INTO Tmp (field(s) )
SELECT
field(s)
FROM tbl
#drop current table
DROP TABLE tbl
#rename temp table to current one
Exec sp_rename 'Tmp', 'tbl'
#drop your temp table
#write alter command to set identitry to Id of current table
good luck

Select data, setting a calculated value into a column

I'm selecting data from a table within a trigger (FOR UPDATE). Some rows I'm selecting have been updated by a transaction, that initiated the trigger, and some rows are not. I'd like to write somewhere in the dataset a flag for every row, which value would be calculated as "id IN (SELECT [id] FROM INSERTED)". This flag would show, is a row updated with the last transaction or not.
Is it possible in SQL?
Sure, I can do 2 separate queries, with 2 different conditions, but the trigger perfomance is real bottleneck...
Here's an example for SQL Server:
if object_id('TriggerTest') is not null
drop table TriggerTest
create table TriggerTest (id int identity, name varchar(50), inLastUpdate bit)
insert TriggerTest (name) values ('joe'), ('barrack'), ('george'), ('dick')
go
create trigger dbo.TriggerTestDelete
on TriggerTest
after update
as begin
declare #date datetime
set #date = GETDATE()
update dbo.TriggerTest
set inLastUpdate =
case when id in (select id from inserted) then 1
else 0
end
end
go
update TriggerTest set name = name where id in (1,2)
update TriggerTest set name = name where id in (1,3)
select * from TriggerTest
This prints:
id name inLastUpdate
1 joe 1
2 barrack 0
3 george 1
4 dick 0