I am working on python sqlite3.
This statement gets records 5 - 14;
SELECT * FROM something LIMIT 5, 10;
But how do I get, lets say the first five and last five records through a single statement?
You can combine output of two select statement like this:
(SELECT * FROM `something` order by some_column_name
limit 0,5)
union
(SELECT * FROM `something` order by some_column_name desc
limit 0,5
)
Specify some ordering of rows, so that it will select rows accordingly.
Maybe the better way is using rowid in your order by clause to get the first and last rows based on inserting the rows:
select test from
(select test,rowid from table1 order by rowid asc limit 0,5)t1
union all
select test from
(select test,rowid from table1 order by rowid desc limit 0,5)t2;
Here is a sample in SQL Fiddle
Say I have 100 records in a certain column in a certain table.
All of these pieces of data in that column are random numbers from 1 to 10
What SQL function can I use to count the number that appears the most within those 100 records and it will display that number alone in the column?
How do I do this? Thanks
Assuming you're using mysql (because of question tags):
SELECT n
FROM tablename
GROUP BY n
ORDER BY COUNT(*) DESC
LIMIT 1
Try a query like this to get the count:
select count(*)
from t
group by col
order by count(*) desc
limit 1
This is MySQL syntax. The limit 1 is database-specific. In SQL Server, for instance, it would be select top 1.
And this to get the number in the column:
select col
from t
group by col
order by count(*) desc
limit 1
This is a known question but the best solution I've found is something like:
SELECT TOP N *
FROM MyTable
ORDER BY Id DESC
I've a table with lots of rows. It is not a posibility to use that query because it takes lot of time. So how can I do to select last N rows without using ORDER BY?
EDIT
Sorry duplicated question of this one
You can get SQL server to select the last N rows with the following query:
select * from tbl_name order by id desc limit N;
I tested JonVD's code, but found it was very slow, 6s.
This code took 0s.
SELECT TOP(5) ORDERID, CUSTOMERID, OrderDate
FROM Orders where EmployeeID=5
Order By OrderDate DESC
You can do it by using the ROW NUMBER BY PARTITION Feature also. A great example can be found here:
I am using the Orders table of the Northwind database... Now let us retrieve the Last 5 orders placed by Employee 5:
SELECT ORDERID, CUSTOMERID, OrderDate
FROM
(
SELECT ROW_NUMBER() OVER (PARTITION BY EmployeeID ORDER BY OrderDate DESC) AS OrderedDate,*
FROM Orders
) as ordlist
WHERE ordlist.EmployeeID = 5
AND ordlist.OrderedDate <= 5
If you want to select last numbers of rows from a table.
Syntax will be like
select * from table_name except select top
(numbers of rows - how many rows you want)* from table_name
These statements work but differrent ways. thank you guys.
select * from Products except select top (77-10) * from Products
in this way you can get last 10 rows but order will show descnding way
select top 10 * from products
order by productId desc
select * from products
where productid in (select top 10 productID from products)
order by productID desc
select * from products where productID not in
(select top((select COUNT(*) from products ) -10 )productID from products)
First you most get record count from
Declare #TableRowsCount Int
select #TableRowsCount= COUNT(*) from <Your_Table>
And then :
In SQL Server 2012
SELECT *
FROM <Your_Table> As L
ORDER BY L.<your Field>
OFFSET <#TableRowsCount-#N> ROWS
FETCH NEXT #N ROWS ONLY;
In SQL Server 2008
SELECT *
FROM
(
SELECT ROW_NUMBER() OVER(ORDER BY ID) AS sequencenumber, *
FROM <Your_Table>
Order By <your Field>
) AS TempTable
WHERE sequencenumber > #TableRowsCount-#N
In a very general way and to support SQL server here is
SELECT TOP(N) *
FROM tbl_name
ORDER BY tbl_id DESC
and for the performance, it is not bad (less than one second for more than 10,000 records On Server machine)
Is "Id" indexed? If not, that's an important thing to do (I suspect it is already indexed).
Also, do you need to return ALL columns? You may be able to get a substantial improvement in speed if you only actually need a smaller subset of columns which can be FULLY catered for by the index on the ID column - e.g. if you have a NONCLUSTERED index on the Id column, with no other fields included in the index, then it would have to do a lookup on the clustered index to actually get the rest of the columns to return and that could be making up a lot of the cost of the query. If it's a CLUSTERED index, or a NONCLUSTERED index that includes all the other fields you want to return in the query, then you should be fine.
select * from (select top 6 * from vwTable order by Hours desc) T order by Hours
Here's something you can try without an order by but I think it requires that each row is unique. N is the number of rows you want, L is the number of rows in the table.
select * from tbl_name except select top L-N * from tbl_name
As noted before, which rows are returned is undefined.
EDIT: this is actually dog slow. Of no value really.
A technique I use to query the MOST RECENT rows in very large tables (100+ million or 1+ billion rows) is limiting the query to "reading" only the most recent "N" percentage of RECENT ROWS. This is real world applications, for example I do this for non-historic Recent Weather Data, or recent News feed searches or Recent GPS location data point data.
This is a huge performance improvement if you know for certain that your rows are in the most recent TOP 5% of the table for example. Such that even if there are indexes on the Tables, it further limits the possibilites to only 5% of rows in tables which have 100+ million or 1+ billion rows. This is especially the case when Older Data will require Physical Disk reads and not only Logical In Memory reads.
This is well more efficient than SELECT TOP | PERCENT | LIMIT as it does not select the rows, but merely limit the portion of the data to be searched.
DECLARE #RowIdTableA BIGINT
DECLARE #RowIdTableB BIGINT
DECLARE #TopPercent FLOAT
-- Given that there is an Sequential Identity Column
-- Limit query to only rows in the most recent TOP 5% of rows
SET #TopPercent = .05
SELECT #RowIdTableA = (MAX(TableAId) - (MAX(TableAId) * #TopPercent)) FROM TableA
SELECT #RowIdTableB = (MAX(TableBId) - (MAX(TableBId) * #TopPercent)) FROM TableB
SELECT *
FROM TableA a
INNER JOIN TableB b ON a.KeyId = b.KeyId
WHERE a.Id > #RowIdTableA AND b.Id > #RowIdTableB AND
a.SomeOtherCriteria = 'Whatever'
MS doesn't support LIMIT in t-sql. Most of the times i just get MAX(ID) and then subtract.
select * from ORDERS where ID >(select MAX(ID)-10 from ORDERS)
This will return less than 10 records when ID is not sequential.
This query returns last N rows in correct order, but it's performance is poor
select *
from (
select top N *
from TableName t
order by t.[Id] desc
) as temp
order by temp.[Id]
use desc with orderby at the end of the query to get the last values.
This may not be quite the right fit to the question, but…
OFFSET clause
The OFFSET number clause enables you to skip over a number of rows and then return rows after that.
That doc link is to Postgres; I don't know if this applies to Sybase/MS SQL Server.
DECLARE #MYVAR NVARCHAR(100)
DECLARE #step int
SET #step = 0;
DECLARE MYTESTCURSOR CURSOR
DYNAMIC
FOR
SELECT col FROM [dbo].[table]
OPEN MYTESTCURSOR
FETCH LAST FROM MYTESTCURSOR INTO #MYVAR
print #MYVAR;
WHILE #step < 10
BEGIN
FETCH PRIOR FROM MYTESTCURSOR INTO #MYVAR
print #MYVAR;
SET #step = #step + 1;
END
CLOSE MYTESTCURSOR
DEALLOCATE MYTESTCURSOR
In order to get the result in ascending order
SELECT n.*
FROM
(
SELECT *
FROM MyTable
ORDER BY id DESC
LIMIT N
) n
ORDER BY n.id ASC
I stumpled acros this issue while using SQL server
What i did to resolve it is order the results descending and giving row number to the results of that, After i filtered the results and turned them around again.
SELECT *
FROM (
SELECT *
,[rn] = ROW_NUMBER() OVER (ORDER BY [column] DESC)
FROM [table]
) A
WHERE A.[rn] < 3
ORDER BY [column] ASC
Easy copy paste answer
To display last 3 rows without using order by:
select * from Lms_Books_Details where Book_Code not in
(select top((select COUNT(*) from Lms_Books_Details ) -3 ) book_code from Lms_Books_Details)
Try using the EXCEPT syntax.
Something like this:
SELECT *
FROM clientDetails
EXCEPT
(SELECT TOP (numbers of rows - how many rows you want) *
FROM clientDetails)
I want to select the last three rows of a table in ascending order. What is the query for that?
SELECT * FROM table ORDER BY DESC LIMIT 3
SELECT *
FROM (
SELECT *
FROM tblname
ORDER BY rowid DESC
) WHERE rownum < 4;
Rowid is the physical address of every row.
Rownum is the psuedo column which is used to generate sequence number of rows.
i am running mysql and i would like to display the last 10 records that were added. what is the select statement for this?
If you have an auto-incrementing ID, you can do this:
SELECT * FROM my_table ORDER BY id DESC LIMIT 10;
If you don't, you'll need some criteria you can order by. An insertion date or something. The LIMIT 10 clause is what you're looking for here.
If you have an autoincrementing ID you can use this:
SELECT *
FROM yourtable
ORDER BY id DESC
LIMIT 10
If you have a column added_datetime that is set to the time of the insert then you can use that instead:
SELECT *
FROM yourtable
ORDER BY added_datetime DESC
LIMIT 10