If use the select statement:
select top (18) * from pippo;
And I use the delete statement:
delete top (18) from pippo;
I would like to know if the 18 selected and deleted rows are the same.
Any help?
EDIT after having accepted the answer:
I have found the following solution here: Delete the 'first' record from a table in SQL Server, without a WHERE condition
WITH q AS
(
SELECT TOP 18 *
FROM pippo
ORDER BY FIELD1 ASC /* You may want to add ORDER BY here */
)
DELETE
FROM q
With this solution I sort all the "pippo" table by FIELD1, and then I delete the first 18 rows.
Without an order by clause, there is no guaranteed ordering so no, they are not guaranteed to be the same.
Related
I want to fire a Query "SELECT * FROM TABLE" but select only from row N+1. Any idea on how to do this?
For SQL Server 2012 and above, use this:
SELECT *
FROM Sales.SalesOrderHeader
ORDER BY OrderDate
OFFSET (#Skip) ROWS FETCH NEXT (#Take) ROWS ONLY
https://stackoverflow.com/a/19669165/1883345
SQL Server:
select * from table
except
select top N * from table
Oracle up to 11.2:
select * from table
minus
select * from table where rownum <= N
with TableWithNum as (
select t.*, rownum as Num
from Table t
)
select * from TableWithNum where Num > N
Oracle 12.1 and later (following standard ANSI SQL)
select *
from table
order by some_column
offset x rows
fetch first y rows only
They may meet your needs more or less.
There is no direct way to do what you want by SQL.
However, it is not a design flaw, in my opinion.
SQL is not supposed to be used like this.
In relational databases, a table represents a relation, which is a set by definition. A set contains unordered elements.
Also, don't rely on the physical order of the records. The row order is not guaranteed by the RDBMS.
If the ordering of the records is important, you'd better add a column such as `Num' to the table, and use the following query. This is more natural.
select *
from Table
where Num > N
order by Num
Query: in sql-server
DECLARE #N INT = 5 --Any random number
SELECT * FROM (
SELECT ROW_NUMBER() OVER(ORDER BY ID) AS RoNum
, ID --Add any fields needed here (or replace ID by *)
FROM TABLE_NAME
) AS tbl
WHERE #N < RoNum
ORDER BY tbl.ID
This will give rows of Table, where rownumber is starting from #N + 1.
In order to do this in SQL Server, you must order the query by a column, so you can specify the rows you want.
Example:
select * from table order by [some_column]
offset 10 rows
FETCH NEXT 10 rows only
Do you want something like in LINQ skip 5 and take 10?
SELECT TOP(10) * FROM MY_TABLE
WHERE ID not in (SELECT TOP(5) ID From My_TABLE ORDER BY ID)
ORDER BY ID;
This approach will work in any SQL version. You need to stablish some order (by Id for example) so all rows are provided in a predictable manner.
I know it's quite late now to answer the query. But I have a little different solution than the others which I believe has better performance because no comparisons are performed in the SQL query only sorting is done. You can see its considerable performance improvement basically when value of SKIP is LARGE enough.
Best performance but only for SQL Server 2012 and above. Originally from #Majid Basirati's answer which is worth mentioning again.
DECLARE #Skip INT = 2, #Take INT = 2
SELECT * FROM TABLE_NAME
ORDER BY ID ASC
OFFSET (#Skip) ROWS FETCH NEXT (#Take) ROWS ONLY
Not as Good as the first one but compatible with SQL Server 2005 and above.
DECLARE #Skip INT = 2, #Take INT = 2
SELECT * FROM
(
SELECT TOP (#Take) * FROM
(
SELECT TOP (#Take + #Skip) * FROM TABLE_NAME
ORDER BY ID ASC
) T1
ORDER BY ID DESC
) T2
ORDER BY ID ASC
What about this:
SELECT * FROM table LIMIT 50 OFFSET 1
This works with all DBRM/SQL, it is standard ANSI:
SELECT *
FROM owner.tablename A
WHERE condition
AND n+1 <= (
SELECT COUNT(DISTINCT b.column_order)
FROM owner.tablename B
WHERE condition
AND b.column_order>a.column_order
)
ORDER BY a.column_order DESC
PostgreSQL: OFFSET without LIMIT
This syntax is supported, and it is in my opinion the cleanest API compared to other SQL implementations as it does not introduce any new keywords:
SELECT * FROM mytable ORDER BY mycol ASC OFFSET 1
that should definitely be standardized.
The fact that this is allowed can be seen from: https://www.postgresql.org/docs/13/sql-select.html since LIMIT and OFFSET can be given independently, since OFFSET is not a sub-clause of LIMIT in the syntax specification:
[ LIMIT { count | ALL } ]
[ OFFSET start [ ROW | ROWS ] ]
SQLite: negative limit
OFFSET requires LIMIT in that DBMS, but dummy negative values mean no limit. Not as nice as PostgreSQL, but it works:
SELECT * FROM mytable ORDER BY mycol ASC LIMIT -1 OFFSET 1
Asked at: SQLite with skip (offset) only (not limit)
Documented at: https://sqlite.org/lang_select.html
If the LIMIT expression evaluates to a negative value, then there is no upper bound on the number of rows returned.
MySQL: use a huge limit number
Terrible API design, the documentation actually recommends it:
SELECT * FROM tbl LIMIT 1,18446744073709551615;
Asked at: MySQL skip first 10 results
Node.js Sequelize ORM implements it
That ORM allows e.g. findAll({offset: without limit:, and implements workarounds such as the ones mentioned above for each different DBMS.
In Faircom SQL (which is a pseudo MySQL), i can do this in a super simple SQL Statement, just as follows:
SELECT SKIP 10 * FROM TABLE ORDER BY Id
Obviously you can just replace 10 with any declared variable of your desire.
I don't have access to MS SQL or other platforms, but I'll be really surprised MS SQL doesn't support something like this.
DECLARE #Skip int= 2, #Take int= 2
SELECT * FROM TABLE_NAME
ORDER BY Column_Name
OFFSET (#Skip) ROWS FETCH NEXT (#Take) ROWS ONLY
try below query it's work
SELECT * FROM `my_table` WHERE id != (SELECT id From my_table LIMIT 1)
Hope this will help
You can also use OFFSET to remove the 1st record from your query result like this-
Example - find the second max salary from the employee table
select distinct salary from employee order by salary desc limit 1 OFFSET 1
For SQL Server 2012 and later versions, the best method is #MajidBasirati's answer.
I also loved #CarlosToledo's answer, it's not limited to any SQL Server version but it's missing Order By Clauses. Without them, it may return wrong results.
For SQL Server 2008 and later I would use Common Table Expressions for better performance.
-- This example omits first 10 records and select next 5 records
;WITH MyCTE(Id) as
(
SELECT TOP (10) Id
FROM MY_TABLE
ORDER BY Id
)
SELECT TOP (5) *
FROM MY_TABLE
INNER JOIN MyCTE ON (MyCTE.Id <> MY_TABLE.Id)
ORDER BY Id
In Oracle PL/SQL I was used to write:
SELECT * FROM MY_TABLE WHERE ROWNUM <= 100;
in order to fetch only the first 100 records of the table named MY_TABLE.
What could be the equivalent SELECT statement in SQL SERVER?
In SQL-Server You can Use TOP to select the no. of rows.
SELECT TOP 100 * FROM MY_TABLE
select top 100 * from tbl
column name is required or use *
SELECT TOP 100 * FROM TABLE
You can also filter rows by using where class
SELECT TOP 100 * FROM YOURTABLE WHERE YOURCONDITION
In SQL Server 2012, you can use OFFSET and FETCH to determine which rows to return. They're documented under ORDER BY; This makes sense since asking for 100 rows, when tables are by definition unordered, gives unpredictable results.
Similarly, if you use other's answers, re: TOP, you should also have an ORDER BY clause, or else it's not defined which rows will be returned.
SELECT TOP 100 * FROM MY_TABLE
Sorry if I misunderstood.
Edit: Must be faster
How do I delete only the top row of a table in SQL Server?
I did:
set rowcount 1;
delete * from table;
set rowcount 0;
But I am not sure if its a good way to do it.
Is there any better way to accomplish that?
UPDATE: oops! #gbn is right, my ORDER BY sample was broken! Updating with correct code sample.
In the most common case where the "top" is based the order of values in a particular column or columns, you can use a CTE and ROW_NUMBER to simulate an ordered TOP:
WITH cte AS
(
SELECT *, ROW_NUMBER() OVER(ORDER BY SomeColumn, OtherColumn) AS RowNum
FROM table
)
DELETE FROM cte
WHERE RowNum <= 1;
See Itzik Ben-Gan's SQLMag article on TOP for more info on this suggested pattern.
If you simply want to delete any row of a set of duplicates, or just want to delete a random row for some reason, then it's safe to omit the ORDER BY and do something simpler:
DELETE TOP (1) FROM table
Quoting from the DELETE docs on MSDN:
TOP ( expression ) [ PERCENT ]
Specifies the number or percent of
random rows that will be deleted.
expression can be either a number or a
percent of the rows. The rows
referenced in the TOP expression used
with INSERT, UPDATE, or DELETE are not
arranged in any order.
Parentheses delimiting expression in
TOP are required in INSERT, UPDATE,
and DELETE statements. For more
information, see TOP (Transact-SQL).
TOP is meaningless without ORDER BY
Use WITH TIES to deal with joint top
You can't use ORDER BY directly in a DELETE so you have to workaround it
Like this:
DELETE foo
FROM (SELECT TOP 1 /*WITH TIES*/ * FROM Mytable ORDER BY WhatDecidesTop) foo;
;WITH Foo AS
(
SELECT TOP 1 /*WITH TIES*/ * FROM Mytable ORDER BY WhatDecidesTop
)
DELETE foo;
The problem with this approach is that it will delete one row at random, you need to be more specific (such as using an order by clause) to make sure you are deleting what you want. Better yet - add a where clause with the primary key for the row you really want to delete and drop the "rowcount" clause altogether.
Dim mySqlCommondDelete As String = "DELETE BOOK_ID,MemberID FROM (SELECT TOP 1 * FROM ISSUE_BOOK) where BOOK_ID = Val(" & deleteBook & ") and MemberID = Val(" & msk & ")"
this is work for ms access sql.i tested...only one first raw deleted...
only first row will be delete
Is there any way to select, for example, first 10 rows of a table in T-SQL (working MSSQL)?
I think I saw something in Oracle defined as rownum meta variable, used in a following way
select * from Users where rownum<=10
But what about MSSQL?
select top(#count) * from users
If #count is a constant, you can drop the parentheses:
select top 42 * from users
(the latter works on SQL Server 2000 too, while the former requires at least 2005)
You can use Microsoft's row_number() function to decide which rows to return. That means that you aren't limited to just the top X results, you can take pages.
SELECT *
FROM (SELECT row_number() over (order by UserID) AS line_no, *
FROM dbo.User) as users
WHERE users.line_no < 10
OR users.line_no BETWEEN 34 and 67
You have to nest the original query though, because otherwise you'll get an error message telling you that you can't do what you want to in the way you probably should be able to in an ideal world.
Msg 4108, Level 15, State 1, Line 3
Windowed functions can only appear in the SELECT or ORDER BY clauses.
SELECT TOP 10 *
FROM Users
Note that if you don't specify an ORDER BY clause then any 10 rows could be returned, because "first 10 rows" doesn't really mean anything until you tell the database what ordering to use.
You can also use rowcount, but TOP is probably better and cleaner, hence the upvote for Mehrdad
SET ROWCOUNT 10
SELECT * FROM dbo.Orders
WHERE EmployeeID = 5
ORDER BY OrderDate
SET ROWCOUNT 0
Try this.
declare #topval int
set #topval = 5 (customized value)
SELECT TOP(#topval) * from your_database
SELECT TOP 10 * FROM TABLE_NAME ORDER BY ORDERED_UNIQUE_COLUMN
DESC
ORDERED_UNIQUE_COLUMN could be your incrementing primary key or a timestamp
Try this:
SELECT * FROM USERS LIMIT 10;
What's the best way to delete all rows from a table in sql but to keep n number of rows on the top?
DELETE FROM Table WHERE ID NOT IN (SELECT TOP 10 ID FROM Table)
Edit:
Chris brings up a good performance hit since the TOP 10 query would be run for each row. If this is a one time thing, then it may not be as big of a deal, but if it is a common thing, then I did look closer at it.
I would select ID column(s) the set of rows that you want to keep into a temp table or table variable. Then delete all the rows that do not exist in the temp table. The syntax mentioned by another user:
DELETE FROM Table WHERE ID NOT IN (SELECT TOP 10 ID FROM Table)
Has a potential problem. The "SELECT TOP 10" query will be executed for each row in the table, which could be a huge performance hit. You want to avoid making the same query over and over again.
This syntax should work, based what you listed as your original SQL statement:
create table #nuke(NukeID int)
insert into #nuke(Nuke) select top 1000 id from article
delete article where not exists (select 1 from nuke where Nukeid = id)
drop table #nuke
Future reference for those of use who don't use MS SQL.
In PostgreSQL use ORDER BY and LIMIT instead of TOP.
DELETE FROM table
WHERE id NOT IN (SELECT id FROM table ORDER BY id LIMIT n);
MySQL -- well...
Error -- This version of MySQL does not yet support 'LIMIT &
IN/ALL/ANY/SOME subquery'
Not yet I guess.
Here is how I did it. This method is faster and simpler:
Delete all but top n from database table in MS SQL using OFFSET command
WITH CTE AS
(
SELECT ID
FROM dbo.TableName
ORDER BY ID DESC
OFFSET 11 ROWS
)
DELETE CTE;
Replace ID with column by which you want to sort.
Replace number after OFFSET with number of rows which you want to keep.
Choose DESC or ASC - whatever suits your case.
I think using a virtual table would be much better than an IN-clause or temp table.
DELETE
Product
FROM
Product
LEFT OUTER JOIN
(
SELECT TOP 10
Product.id
FROM
Product
) TopProducts ON Product.id = TopProducts.id
WHERE
TopProducts.id IS NULL
This really is going to be language specific, but I would likely use something like the following for SQL server.
declare #n int
SET #n = SELECT Count(*) FROM dTABLE;
DELETE TOP (#n - 10 ) FROM dTable
if you don't care about the exact number of rows, there is always
DELETE TOP 90 PERCENT FROM dTABLE;
I don't know about other flavors but MySQL DELETE allows LIMIT.
If you could order things so that the n rows you want to keep are at the bottom, then you could do a DELETE FROM table LIMIT tablecount-n.
Edit
Oooo. I think I like Cory Foy's answer better, assuming it works in your case. My way feels a little clunky by comparison.
I would solve it using the technique below. The example expect an article table with an id on each row.
Delete article where id not in (select top 1000 id from article)
Edit: Too slow to answer my own question ...
Refactored?
Delete a From Table a Inner Join (
Select Top (Select Count(tableID) From Table) - 10)
From Table Order By tableID Desc
) b On b.tableID = A.tableID
edit: tried them both in the query analyzer, current answer is fasted (damn order by...)
Better way would be to insert the rows you DO want into another table, drop the original table and then rename the new table so it has the same name as the old table
I've got a trick to avoid executing the TOP expression for every row. We can combine TOP with MAX to get the MaxId we want to keep. Then we just delete everything greater than MaxId.
-- Declare Variable to hold the highest id we want to keep.
DECLARE #MaxId as int = (
SELECT MAX(temp.ID)
FROM (SELECT TOP 10 ID FROM table ORDER BY ID ASC) temp
)
-- Delete anything greater than MaxId. If MaxId is null, there is nothing to delete.
IF #MaxId IS NOT NULL
DELETE FROM table WHERE ID > #MaxId
Note: It is important to use ORDER BY when declaring MaxId to ensure proper results are queried.