Running into some issues when trying to retrieve the last value in a specific column, from a table and assign it into a variable.
Looking for the last int in a column "id" that is a primary key basically.
So I have a variable like "lastValue" in a select statement like :
select last(id) into lastValue from test_table
Not sure on an exact, or best way to accomplish this.
(on mobile, please forgive formatting)
A typical way to solve this is with order by and limit:
select id
from test_table
order by id desc
limit 1;
Of course, in this case, you could simply use:
select max(id)
from test_table;
But the first method allows you to choose whichever variables you want from the row with the maximum value.
Related
How do I we get last row in SQL Server if we don't have primary id and numeric column? For example we only have a name and a few other columns in the table
If you mean the highest name, alphabetically,
select max(columnName) from tableName
If you mean the last row added to the table, it's not possible unless you have a column with the date/time inserted, or some other value like an identity column.
Maybe if you have a column for insertedDate you could do something like this:
select top (1) * from tableName order by insertedDate DESC
If not, for future use if you don't want an ID column, maybe you can add a default constraint for inserted date to pick from the system date, so you wouldn't have to add anything when you insert.
With no definition of 'last row'... :
select top 1 *
from t
order by Name desc
here is my situation,
I have 2 tables,
1st table has all records, and it has IDs
2nd table has new records and it doesnt have ID, yet.
I want to generate ID for 2nd table with max(id) + 1 from 1st table.
when i do this, it makes all rows same id number, but i want to make it unique increment number.
e.g
select max(id) from table1 then it gives '997040'
I want to make second table rows like;
id
997041
997042
997043
997044
i think i need to use cursor or whileloop, or both, but i could not create the actual query.
sorry about bad explanation, i am so confused now
Use ROWNUM to generate incrementing row numbers. E.g.:
SELECT someConstant + ROWNUM FROM source.
CREATE TABLE table_name
(
ID int IDENTITY(997041,1) PRIMARY KEY
)
I hope this sql query would work!!
Or refer http://www.w3schools.com/sql/sql_autoincrement.asp
I need to update a SQL Server table periodically by inserting new records into it.
The table has an ID column in the form of Company0001 through Company0020 right now.
Let's say I added one record of a new company into the table. I want to fill the ID column with Company0021 for this new record. Can anyone suggest a way to do this?
Thank you so much!
I would strongly suggest to use an identity column. Identity is a mechanism designed and used for this actual purpose and therefore it would be much better in terms of performance.
Nevertheless, if you insist on IDs on the format 'CompanyXXX' I would suggest to use a varchar column. Then you would add a trigger on the insert and update operations. When the trigger runs, it would find out the last 'CompanyXXX' and form the new one. If you need help regarding triggers, you could check this tutorial.
Hope I helped!
My suggestion would be to have an autoincrement field, and then concatenate the company name with the ID.
If you don't want to do it with an ID field, do you want it to happen automatically, or are you going to manage it manually? If automatically, you'll need to write a trigger to intercept the INSERT and change the value there. Shouldn't be too hard to do.
I'd seriously recommend NOT doing this and going down the autoincrement field path. It's better.
Add another column to the table to hold an integer value (in this example SNo) and then write query as
declare #SNo int
select #SNo=max(SNo)+1 from Table_Name
insert into Table_Namevalues (#SNo,'company'+right('0000'+cast(#SNo as varchar(10)),4))
And then see the result
Hope this helps
In case a solution is required as, having only one column with values in desired format you can create a function as:
create table table1(id varchar(100));
Go
create function dbo.fn_GetCompanyIdentity ()
returns varchar(100)
as
begin
declare #CompanyIdentify varchar(100);
select #CompanyIdentify =
(select 'Company' +
right ('00000' + cast (
(
(
case when Not exists (select ROW_NUMBER() over( order by (select 1)) from Table1 ) then 1
else (select top 1 ROW_NUMBER() over( order by (select 1)) as currentRownumber from Table1 order by currentRownumber desc) + 1
end
)
)
as varchar(4))
,4));
return #CompanyIdentify;
end;
go
and then use the function in insert statement as :
insert into Table1 (id)
select dbo.fn_GetCompanyIdentity();
Go
Hope this helps!!
Why dont you just create an auto-increment column and then concatenate "Company" to this column in another column. And for presentation just select "Company+autoincrement" column.
I have a query like below and it generate a temporary table automatically based on parameter. So, the number of column of this table can be vary. Now , i need to add an auto incremental id column into this table.How i do it?
SELECT #SourceFields INTO ##StoreSourceInfo FROM testdb.dbo.#SourceTable
Note: 1) Number of source field & name of table pass using the parameter #SourceFields & #SourceTable.
2) So, the number of column can be vary on ##StoreSourceInfo table.
Current Result:
select * from ##StoreSourceInfo shows only the available column.
Expected Result:
select * from ##StoreSourceInfo query will show an additional auto incremental id column & all rest of the column available in the temp table.
Hope you get me. Thanks in advance.
SELECT
IDENTITY(INT, 1, 1) AS id
INTO #Temptable
FROM User
You can use row_number function
Select ROW_NUMBER() over (order by T.field1) rownum
, T.field1, T.field2 into #temp1
from #Table T
Use the identity function. See the link for an example. http://msdn.microsoft.com/en-us/library/ms189838.aspx
You have to try with following query to get your excepted result to add a extra auto increment column :
SELECT
IDENTITY(INT, 1,1) AS Rank,
#SourceFields
INTO
##StoreSourceInfo
FROM
testdb.dbo.#SourceTable
Means apply IDENTITY function...
The reason I need this for is that I made a column on my table called display_order, for now it's smallint and the numbers were pre-determined.
However, when I insert a new record with my software I don't know how to get the highest number in that column and add 1, so I thought about the possibility of an auto-incremented column where if I change 8 to 9 it will change everything else accordingly.
Is this possible?
The answer to your question is "No" IDENTITY is the only auto incrementing capability (and these columns are not updatable)
But if this is a display_order field can't you just make it float to allow you to insert items between other items rather than having to shift all other items down to create a gap?
However, when I insert a new record with my software I don't know how to get the highest number in that column and add 1,
Insert MyTable( display_order, .... )
Select (
Select Max(display_order) + 1
From MyTable As T1
), ...
From MyTable
However, I wouldn't recommend this. If display_order is user settable, then I would simply assume relative values. Thus, it wouldn't matter if a user added two values with a display_order = 0. If you really want to go the extra mile and provide the ability to resequence the display_order, you could do it like so:
Update MyTable
Set display_order = Z.NewSeq
From (
Select PKCol
, Row_Number() Over ( Order By display_order ) As NewSeq
From MyTable
) As Z
Join MyTable As T
On T.PKCol = Z.PKCol
Because you only get one IDENTITY column per table, I would probably use a trigger or other mechanism (if there's a centralized insertion stored proc) to default it to one more than the highest number in the table if not provided. This avoids having to SET IDENTITY_INSERT or anything like that.