I am working on Windows Form Application and it accesses database in SQL Server 2014. I have EmployeeTable which I retrieve data from, and display all the records in DataGridView. In this table, I have a column SequenceID, which basically increments from 1 up to the number of records in this table, but this is not the same as AUTO INCREMENT in that SequenceID gets updated each time the table is modified, and keeps the numerical order no matter how many times new records get inserted or some records are deleted. For example, if the data looks like
SequenceID | Name
1 | John
2 | Mary
3 | Robert
and Mary is removed, then the resulting table needs to look like
SequenceID | Name
1 | John
2 | Robert
In order to achieve this, I used the best answer by zombat from Update SQL with consecutive numbering, and it was working great until I used ORDER BY expression.
This EmployeeTable also has DateAdded column, containing the date when the record was inserted. I need to display all records ordered by this DateAdded column, with the oldest record shown at the top and the newest at the bottom in addition to the correct SequenceID order. However, it gets messed up when a record is deleted, and a new one is inserted.
If I insert 3 records like,
SequenceID | Name | DateAdded
1 | John | 9/25/2017
2 | Mary | 9/26/2017
3 | Robert | 9/27/2017
and remove Mary, it becomes
SequenceID | Name | DateAdded
1 | John | 9/25/2017
2 | Robert | 9/27/2017
and this is good so far. However, if I add another record Tommy on, say, 9/28/2017, which should be added at the bottom because it is the newest, it results in something like,
SequenceID | Name | DateAdded
1 | John | 9/25/2017
3 | Robert | 9/27/2017
2 | Tommy | 9/28/2017
The ORDER BY is working fine, but it messes up the SequenceID, and I am not sure why this is happening. All I am doing is,
SELECT *
FROM EmployeeTable
ORDER BY DateAdded
I tried placing zombat's SQL command both before and after this SQL command, but neither worked. It seems to me like when I delete a row, the row has an invisible spot, and a new record is inserted in there.
Is there any way to fix this so I can order the records by DateAdded and still have the SequenceID working correctly?
If you need id for GUI (presentation only) you could use:
SELECT ROW_NUMBER() OVER(ORDER BY DateAdded) AS sequenceId, Name, DateAdded
FROM EmployeeTable
ORDER BY DateAdded;
EDIT:
I am trying to update the SequenceID, but it is not getting updated
You should not try to reorder your table every time. It doesn't make sense.
Related
My table:
Items | Price | UpdateAt
1 | 2000 | 02/02/2015
2 | 4000 | 06/04/2015
3 | 2150 | 07/05/2015
4 | 1800 | 07/05/2015
5 | 5540 | 08/16/2015
4 | 1700 | 12/24/2015
5 | 5200 | 12/26/2015
2 | 3900 | 01/01/2016
4 | 2000 | 06/14/2016
As you can see, this is a table that keeps items' price as well as their old price before the last update.
Now I need to find the rows which :
UpdateAt is more than 1 year ago from now
Must have updated price at least once ever since
Aren't the most up-to-date price
So with those conditions, the result from the above table should be :
Items | Price | UpdateAt
2 | 4000 | 06/04/2015
4 | 1800 | 07/05/2015
I can achieve what I need with this
Declare #LastUpdate date set #LastUpdate = DATEADD(YEAER, -1, GETDATE())
select Items, UpdateAt from ITEM_PRICE where Items in (
select Items from (
select Items, count(Items) as C from ITEM_PRICE group by Items) T
where T.C > 1)
and UpdateAt < #LastUpdate
But since I am still a newbie in sqlserver, and this need to be done in vb.net, passing along that query with lots of select in it seems sloppy and hard to maintain.
So, I would like to ask if anyone can give me a simpler solution ?
Sorry, i edited my question as I need one more condition to be met after trying #Tim Biegeleisen's answer, which is indeed the correct one for the question before edit. And I can't figure this out anymore.
Why I need all those condition, it's because I'm having to clean up the table: Clearing off the data that's older than 1 year, while still keeping the most up-to-date item price.
In my answer below, I use a subquery to identify all items which appear in the table during the last year. This is the requirement of having an updated price "at least once ever since." In the outer query, I restrict to only records which are older than one year from now, which is the other part of the requirement. An INNER JOIN is used, because we want to filter off records which do not meet both criteria.
SELECT t1.Items, t1.Price, t1.UpdateAt
FROM ITEM_PRICE t1
INNER JOIN
(
SELECT DISTINCT Items
FROM ITEM_PRICE
WHERE UpdateAt > DATEADD(year, -1, GETDATE())
) t2
ON t1.Items = t2.Items
WHERE t1.UpdateAt <= DATEADD(year, -1, GETDATE())
Once again, SQL Fiddle is having problems simulating SQL Server. But I went ahead and created a Fiddle in MySQL, which looks nearly identical to my SQL Server answer. You can verify that the logic and output are correct.
SQLFiddle
I have a table1 like below having more than 400k records.Below I'm just showing example, how it look likes. I want to write some query to iterate through each row and find its corresponding date; if all dates are present for the account ID , then I have to update another table2 "Yes". And, if any one of the date is null (for any account ID) then I have to update table2 flag as "No".
This is my source table1.
Table1
Account ID | Date
----------- |------------
1 | 12-03-2015
1 | 11-03-2015
1 | 11-04-2015
1 | 01-03-2015
2 | 06-03-2015
2 | 11-03-2015
2 | Null
2 | 01-03-2015
This is how the table2 result will look like (after query execution)
Table2
Account ID | Flag
-----------|------
1 | Yes
2 | No
2ndly, if after few days, Date of Account ID is changed from Null to an actual date (say 07-07-2015), then Table2 "Account ID 2" value should change from "No" to "Yes". So after few days the Table2 should look like this
Account ID | Flag
-----------|------
1 | Yes
2 | Yes
Hope I have explained it correctly.I'm thinking to use cursor, however, I'm not sure how to use this and will cursor really solve this problem? Is there any other ways to achieve this? Checked on net, however, not able to get suitable solution, please help?
You need to change your mindset from looking at every row. This is a very simple set based solution. You should also use better names than DATE and Flag but whatever, this will return the desired output you are after.
select AccountID
, case MIN(case when [Date] is null then '' else [DATE] end) when '' then 'No' else 'Yes' end as Flag
from Table1
group by AccountID
I have data in my PeopleInfo table where there are some people that have multiple records that I am trying to combine together into one record for a view.
All people data is the almost the same except for the PlanId and PlanName. So:
| FirstName | LastName | SSN | PlanId | PlanName | Status | Price1 | Price2 |
|-----------|----------|-----------|--------|----------|-----------|---------|--------|
| John | Doe | 123456789 | 1 | Plan A | Primary | 9.00 | NULL |
|-----------|----------|-----------|--------|----------|-----------|---------|--------|
| John | Doe | 123456789 | 2 | Plan B | Secondary | NULL | 5.00 |
I would like to only to have one John Doe record in my view that looked like this:
| FirstName | LastName | SSN | PlanId | PlanName | Status | Price1 | Price2 |
|-----------|----------|-----------|--------|----------|-----------|---------|--------|
| John | Doe | 123456789 | 1 | Plan A | Primary | 9.00 | 5.00 |
Where the Primary status determines which PlanId and PlanName to show. Can anyone help me with this query?
declare #t table ( FNAME varchar(10), LNAME varchar(10), SSN varchar(10), PLANID INT,PLANNAME varchar(10),stat varchar(10),Price1 decimal(18,2),Price2 decimal(18,2))
insert into #t (FNAME,LNAME,SSN,PLANID,PLANNAME,stat,Price1,Price2)values ('john','doe','12345',1,'PlanA','primary',9.00,NULL),('john','doe','12345',1,'PlanB','secondary',Null,8.00)
select
FNAME,
LNAME,
SSN,
MAX(PLANID)PLANID,
MIN(PLANNAME)PLANNAME,
MIN(stat)stat,
MIN(Price1)Price1,
MIN(Price2)Price2 from #t
GROUP BY FNAME,LNAME,SSN
(I can't yet add a comment, so have an answer.)
The only thing that troubles me here is that i am also determining which PlanId and PlanName since they are different and i want to show a specific one based off of the Status field of both records.
Then you don't even need GROUPing. It would be much simpler. Just SELECT WHERE 'Primary' = PlanName. Assuming that (A) there will always be this PlanName for each user, and (B) You are happy to ignore all others.
P.S. If you will only be using Primary and Secondary PlanNames, you might want to change the column to a bit named something like isPrimaryPlan where 1 indicates true and 0 false. However, if you might bring in e.g. Bronze and Consolation Prize Plans later, then you'll need to retain a more variable datatype. Perhaps store the plans in a separate table and have an int FOREIGN KEY to it... I could go on!
OK, I'm back after having a sleep, which has improved my brain slightly,
First, let the record reflect that I don't like the database design here. The People and Plans should be separate tables, linked by foreign keys - via a 3rd table, e.g. PeoplePlans. That takes me to another point: the people here have no primary key (at least not that you have specified). So when writing the below, I had to pick the SSN, assuming that will always be present and unique.
Anyway, something like this should work, with the caveat that I'm not going to replicate the database structure to test it.
select
FirstName,
LastName,
SSN,
PlanId,
PlanName,
Status,
_ca._sum_Price1,
_ca._sum_Price2
from
PeopleInfo as _Primary
cross apply (
select
sum(Price1) as _sum_Price1,
sum(Price2) as _sum_Price2
from
PeopleInfo
where
_Primary.SSN = SSN
) as _ca
where
'Primary' = Status;
This SELECTs all People with Primary status in order to get you those rows. It then CROSS APPLYs their Primary and any other rows and takes the summed Prices.
Hopefully this makes sense. If not, you'll have to do some reading about CROSS APPLY, in addition to about good relational database design. ;-)
I want to use an aggregate function in SQL Server to sum the number of seats:
The table is like that (it's all the same software just version changes)
OrderID | CustomerID | ProductID | Product Name | No of Seats
1 | 11 | 351-0212-4 | soft v601,Download | 3
2 | 11 | 361-0313-5 | soft v701,Upgrade | 2
3 | 12 | 341-1210-4 | soft v501,Download | 5
4 | 12 | 351-0212-5 | soft v601,Upgrade | 2
...
And I want a result like
Sum(no of seats)
8
So If a customer already bought the software but have upgraded keep number of seats for the customer.
e.g.:
Customer 11 bought 3 licences of our soft and then he bought two upgrades of a newer vesion so the sum for him should be 3 instead of 5.
Is that something possible to do in SQL ?
I hope I've been clear if not let me know.
Thanks in advance.
something like
select CustomerID, sum([No of Seats])
from <your table>
where [Product Name] not like '%upgrade%'
group by CustomerID
But in general - filter out those you don't want to see in the results and then sum. And if you want total number (not per customer):
select sum([No of Seats])
from <your table>
where [Product Name] not like '%upgrade%'
you should add boolean column, like 'isActive', then your select can be like this
select customerid, sum(numberOfSeats) from table
where isActive = 1
group by customerid
You have some normalization problems. The Product Name column is (presumably) redundant with the ProductID column, plus Product Name
apparently carries two logically distinct pieces of information: the name itself, and whether that product is an upgrade.
It would be better to split this into two tables, say Products and Orders. The Products table would have columns ProductID (primary key), Product_Name, and Is_Upgrade, and the Orders table would have columns OrderID (primary key), CustomerID (foreign key), ProductID (foreign key), and NumberOfSeats.
Given what you now have, however, and assuming that you want to avoid counting seats where the product name ends in 'Upgrade', you seem to want a query along these lines:
SELECT SUM("No of seats")
FROM Orders
WHERE CustomerID = 11 AND "Product Name" NOT LIKE '%Upgrade'
I have a database table called A and now i have create a new table called B and create some columns of A in table B.
Eg: Suppose following columns in tables
Table A // The one already exists
Id, Country Age Firstname, Middlename, Lastname
Table B // The new table I create
Id Firstname Middlename Lastname
Now the table A will be look like,
Table A // new table A after the modification
Id, Country, Age, Name
In this case it will map with table B..
So my problem is now i need to kind of maintain the reports which were generated before the table modifications and my friend told me you need to have a data migration..so may i know what is data migration and how its work please.
Thank you.
Update
I forgot to address the reporting issue raised by the OP (Thanks Mark Bannister). Here is a stab at how to deal with reporting.
In the beginning (before data migration) a report to generate the name, country and age of users would use the following SQL (more or less):
-- This query orders users by their Lastname
SELECT Lastname, Firstname, Age, Country FROM tableA order by Lastname;
The name related fields are no longer present in tableA post data migration. We will have to perform a join with tableB to get the information. The query now changes to:
SELECT b.Lastname, b.Firstname, a.Country, a.Age FROM tableA a, tableB b
WHERE a.name = b.id ORDER BY b.Lastname;
I don't know how exactly you generate your report but this is the essence of the changes you will have to make to get your reports working again.
Original Answer
Consider the situation when you had only one table (table A). A couple of rows in the table would look like this:
# Picture 1
# Table A
------------------------------------------------------
Id | Country | Age | Firstname | Middlename | Lastname
1 | US | 45 | John | Fuller | Doe
2 | UK | 32 | Jane | Margaret | Smith
After you add the second table (table B) the name related fields are moved from table A to table B. Table A will have a foreign key pointing to the table B corresponding to each row.
# Picture 2
# Table A
------------------------------------------------------
Id | Country | Age | Name
1 | US | 45 | 10
2 | UK | 32 | 11
# Table B
------------------------------------------------------
Id | Firstname | Middlename | Lastname
10 | John | Fuller | Doe
11 | Jane | Margaret | Smit
This is the final picture. The catch is that the data will not move from table A to table B on its own. Alas human intervention is required to accomplish this. If I were the said human I would follow the steps given below:
Create table B with columns Id, Firstname, Middlename and Lastname. You now have two tables A and B. A has all the existing data, B is empty .
Add a foreign key to table A. This FK will be called name and will reference the id field of table B.
For each row in table A create a new row in table B using the Firstname, Middlename and Lastname fields taken from table A.
After copying each row, update the name field of table A with the id of the newly created row in table B.
The database now looks like this:
# Table A
-------------------------------------------------------------
Id | Country | Age | Firstname | Middlename | Lastname | Name
1 | US | 45 | John | Fuller | Doe | 10
2 | UK | 32 | Jane | Margaret | Smith | 11
# Table B
------------------------------------------------------
Id | Firstname | Middlename | Lastname
10 | John | Fuller | Doe
11 | Jane | Margaret | Smith
Now you no longer need the Firstname, Middlename and Lastname columns in table A so you can drop them.
voilà, you have performed a data migration!
The process I just described above is but a specific example of a data migration. You can accomplish it in a number of ways using a number of languages/tools. The choice of mechanism will vary from case to case.
Maintenance of the existing reports will depend on the tools used to write / generate those reports. In general:
Identify the existing reports that used table A. (Possibly by searching for files that have the name of table A inside them - however, if table A has a name [eg. Username] which is commonly used elsewhere in the system, this could return a lot of false positives.)
Identify which of those reports used the columns that have been removed from table A.
Amend the existing reports to return the moved columns from table B instead of table A.
A quick way to achieve this is to create a database view that mimics the old structure of table A, and amend the affected reports to use the database view instead of table A. However, this adds an extra layer of complexity into maintaining the reports (since developers may need to maintain the database view as well as the reports) and may be deprecated or even blocked by the DBAs - consequently, I would only recommend using this approach if a lot of existing reports are affected.