SQL OFFSET Query

For loading huge amounts of data from a relational database on a machine with limited memory and preventing an out-of-memory exception, use SQL Server OFFSET FETCH. In SQL Server, the FETCH and OFFSET clauses are used in conjunction with the SELECT and ORDER BY clauses. It can be used with the order by clause as an alternative.

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Following are the definition of OFFSET and FETCH clause.

OFFSET – It specifies the number of rows to skip before it starts to return rows from the query expression. It is mandatory.

FETCH – It specifies the number of rows to return after the OFFSET clause has been processed. It is an optional.

SYNTAX :

SELECT  col1, col2, ....
FROM table_name
WHERE  conditions
ORDER BY column_list [ASC |DESC] 
OFFSET offset_row_count {ROW | ROWS} 
FETCH {FIRST | NEXT} fetch_row_count {ROW | ROWS} ONLY

Example 1: Let's look at how to use the OFFSET and FETCH clauses in practice. Assume we have a customer table with the appropriate details :

Assume you want to get the first five rows of records and then the next four rows of records. We can simply accomplish this by utilising the OFFSET and FETCH clauses. The question is as follows:

SELECT * FROM customer   
ORDER BY c_name   
OFFSET 5 ROWS   
FETCH NEXT 4 ROWS ONLY;

The statement's execution produces the following output, with OFFSET 5 skipping the first five rows and FETCH 4 ROWS ONLY displaying the necessary results.

Example 2: Beginning with SQL Server 2012, OFFSET FETCH is a functionality added to the ORDER BY clause. It can be used to retrieve a given number of rows from a particular index. We have a query that returns 40 rows, then we need to remove 10 rows from the 10th row, for instance:

SELECT *
FROM Table
ORDER BY ID
OFFSET 10 ROWS
FETCH NEXT 10 ROWS ONLY

OFFSET 10 skips 10 rows in the query above, while FETCH 10 ROWS ONLY extracts only 10 rows.

Refer to the following official documents for more details on the ORDER BY clause and the OFFSET FETCH feature: Limiting the number of rows returned with OFFSET and FETCH.

Example 3: Lets take an example of using OFFSET and FETCH clause with order by clause:

If you wish to ignore the first four rows and choose the next five, use the FETCH clause with the OFFSET clause, as seen in the query below.

SELECT * FROM Student ORDER BY  studId
OFFSET 4 ROWS FETCH NEXT 5 ROWS ONLY;

To accomplish paging in SQL Server, use the OFFSET and NEXT operators. The OFFSET operator starts at the beginning and offsets the next K number of search results, whereas the FETCH NEXT operator receives the NEXT N results, where K and N are integers.

FETCH returns a set of rows. FETCH is used in conjunction with OFFSET and cannot be used by itself.

The FETCH argument is used to return a set of number of rows. FETCH can’t be used itself, it is used in conjuction with OFFSET.

Syntax :

The basic syntax for using FETCH NEXT command in a SELECT query is as follow:

SELECT column_name1, column_name2, ...
FROM table_name
ORDER BY sort_expression
OFFSET n ROWS
FETCH NEXT m ROWS ONLY;

The parameters used in the above mentioned syntax are as follows:

column_name1, column_name2,...: table columns or fields that must be retrieved.

table_name: the database table from which the columns must be retrieved.

sort_expression is fully optional, but it is regularly used in conjunction with FETCH commands. If you must utilise it, you must define the order and expression on which the result set must be sorted.

OFFSET n ROWS: This command is used to filter out the first n records. It's used in conjunction with FETCH NEXT to retrieve the specified row window. For example, if we want to skip the first 10 rows and start fetching from row 11, we must set the offset field to 10.

Example 1: Print the Fname, Lname from 3rd to 6th tuple of Employee table when sorted according to the Salary.

SELECT Fname, Lname
FROM Employee
ORDER BY Salary
OFFSET 2 ROWS
FETCH NEXT 4 ROWS ONLY;

Example 2: Let's have a look at an example. Assume you wish to display 20 rows from the Products table, beginning with row 11 in the result set, and ordering them by product name. The page-up button on the form should increase the offset by 20 and the page-down button should decrease it by 20. (after checking limits).

SELECT * FROM dbp.Products AS P
ORDER BY P.productName
OFFSET 10 ROWS
FETCH NEXT 20 ROWS ONLY

Example 3: OFFSET NEXT in action. The syntax of OFFSET NEXT is as follows:

SELECT * FROM Table_Name
ORDER BY COLUMN_NAME/S
OFFSET Number_of_rows_to_Skip ROWS
FETCH NEXT Number_of_rows_to_Fetch ROWS ONLY

Example 4: Starting with the third row in the registrations table, locate the username and city that match to the first three records.

SELECT username,city
FROM registrations
OFFSET 2 ROWS
FETCH NEXT 3 ROWS ONLY;

A table in a SQL server database can have an unlimited number of records. Filling a grid control with all of these records slows down the web page. You must split the quantity of records and populate the web page accordingly. Pagination is the process of dividing a SELECT query result set's number of records into multiple pages. The ROW NUMBER function or the OFFSET FETCH clause can be used to do this.

Pagination is commonly used in applications where the user can click Previous/Next to traverse between the pages that make up the results, or click on a page number to get straight to that page.

The OFFSET and FETCH options of the ORDER BY clause in SQL Server can be used to paginate the output while performing queries.

Syntax:

The Syntax of the OFFSET FETCH pagination:

SELECT columnName(s)
FROM tableName
ORDER BY columnName
OFFSET Rows_To_Skip
FETCH NEXT Rows_To_Fetch ROWS ONLY;

Example 1: This instance is nearly identical to the last one, with the exception that you can provide the page number instead of the row number.

DECLARE 
 @PageNumber int = 1,
 @RowsPerPage int = 3;
SELECT *  
FROM Genres
ORDER BY GenreId ASC
 OFFSET (@PageNumber - 1) * @RowsPerPage ROWS
 FETCH NEXT @RowsPerPage ROWS ONLY;

Result:

Example 2: This stored procedure returns a given number of rows (determined by the argument @pageSize) sorted by the FirstName column for the passed page number (determined by the parameter @pageNum):

CREATE PROCEDURE dbo.GetCustomersPagedDatabyFetch
(
  @pageNum INT,
  @pageSize INT
)
AS
BEGIN
    SELECT Id, FirstName, LastName
    FROM dbo.Customers WITH(NOLOCK)
    ORDER BY FirstName
    OFFSET (@pageNum - 1) * @pageSize ROWS
    FETCH NEXT @pageSize ROWS ONLY 
END

Try invoking the preceding Stored Procedure to receive the first page data sorted by FirstName, assuming a page size of 3 for our instance.

EXEC dbo.GetCustomersPagedDatabyFetch 
@pageNum = 1, @pageSize = 3

Example 3: The below query populates the first page with first 10 records.

DECLARE @PageNo INT = 1
DECLARE @RowsPerPage INT = 10 --Records Per Page
DECLARE @RowsToSkip INT  =  (@PageNo -1) * @RowsPerPage

SELECT * FROM Course 
ORDER BY department, id 
OFFSET  @RowsToSkip ROWS
FETCH NEXT @RowsPerPage ROWS ONLY;

To employ COUNT The ORDER BY clause is directly connected with the OFFSET and FETCH clauses. They let you limit the number of rows that a query returns. However, an OFFSET-FETCH cannot exist without an ORDER BY clause.

Example 1: The top three rows, marked in red above, are the ones that will be eliminated during an OFFSET-FETCH statement, as illustrated below.

SELECT MiddleName
,COUNT(MiddleName) AS 'MnameCount'
FROM Person.Person
WHERE MiddleName IS NULL OR MiddleName IS NOT NULL
GROUP BY MiddleName
ORDER BY MiddleName
OFFSET 3 ROWS FETCH NEXT 5 ROWS ONLY;
GO

Example 2: The COUNT() OVER() function is used. (I'm not sure if it was the server because it took 40 seconds to return 10 records but then worked well later.) This method worked in all cases without the need for COUNT() OVER() and achieves the same result:

DECLARE 
    @PageSize INT = 10, 
    @PageNum  INT = 1;

WITH TempResult AS(
    SELECT ID, Name
    FROM Table
), TempCount AS (
    SELECT COUNT(*) AS MaxRows FROM TempResult
)
SELECT *
FROM TempResult, TempCount
ORDER BY TempResult.Name
    OFFSET (@PageNum-1)*@PageSize ROWS
    FETCH NEXT @PageSize ROWS ONLY

Example 3: use COUNT(*) OVER() ... here is a quick example using sys.all_objects:

DECLARE 
  @PageSize INT = 10, 
  @PageNum  INT = 1;

SELECT 
  name, object_id, 
  overall_count = COUNT(*) OVER()
FROM sys.all_objects
ORDER BY name
  OFFSET (@PageNum-1)*@PageSize ROWS
  FETCH NEXT @PageSize ROWS ONLY;

However, this should only be used on small data sets; on bigger data sets, efficiency can be poor. Managing indexed views (which only works if the result is unfiltered or you know the WHERE clauses in advance) and employing ROW_NUMBER() trickery are two superior solutions described in this Paul White essay.

Example 4: The OFFSET-FETCH syntax is used. This is handy for retrieving a single page of records from a bigger (sorted) collection. However, you'd generally do a second query to count the entire number of records. The T-SQL code below demonstrates how to perform a total count as part of the query that delivers the requested page. Although the count is repeated for each entry, it removes the need for two queries.

select FirstName, LastName, COUNT(*) over () as TotalCount
from Person
where LastName like 'mc%'
order by LastName, FirstName
offset 500 rows
fetch next 100 rows only;

Example 1: If this is not what you expected, you can add an aggregate function to your query to make the order by consistent (I used MIN here):

SELECT ed."event"
FROM public."eventdate" as ed
GROUP BY ed."event"
ORDER BY MIN(ed."start_date") ASC
LIMIT 5
OFFSET 0

Example 2: I have two tables, events and eventdate, with a row event in eventdate matching the id column in events. (An event can therefore have numerous dates.)

SELECT ed."event"
FROM public."eventdate" as ed
GROUP BY ed."event"
ORDER BY ed."start_date" ASC
LIMIT 5
OFFSET 0

but the following error is thrown:

To be clear, I'm looking for a list of ids with a maximum of 5 entries and no duplicates (a duplicate would just be "removed").

Given the following set:

If you simply want to see the first few rows of a query, limit the results or use table pagination.

The limit option limits the number of rows retrieved from a query, whereas the offset option allows you to exclude a defined number of rows before the result set begins. Restrict and offset are used together to omit both rows and limit the number of rows returned.

You can use limit and offset on these statement types:

• select statements
• Device tables
• Union
• Non-correlated subqueries

Limit and offset are usually natural numbers that are smaller than the order by clause's outcome size.

If you choose a negative number for limit or offset, you'll get an error message.

When the offset value is greater than or equal to the result size of the order by clause, the output of the limit clause is blank.

Only the rows from offset to the end of the order by result are delivered when the values of limit and offset are greater than the outcome size.

MySQL doesn't have a PAGE clause, but it does offer an OFFSET clause that allows you to change the starting point for counting up to the LIMIT number.

Multiply the LIMIT clause value by the page number you're searching for minus one to get the value of OFFSET.

When both the limit and offset clauses are used simultaneously, the order by clause provides the results in the appropriate order and avoids a result set with undesired sort order.

Example 1: There are 11 users in the database above, and we use the following query to get the first two:

PAGE = 1
LIMIT = 2
OFFSET = (PAGE-1) * LIMIT
OFFSET = (1-1) * 2
OFFSET = 0 * 2
OFFSET = 0

We deduct 1 from the page number because the offset beginning value is 0, not 1.

SELECT `id`, `name`
FROM `users`
LIMIT 2
OFFSET 0

Example 2: Starting with the seventh row (that is, the row immediately after the number supplied by offset), this instance imposes a limit of five rows:

select * from table1 order by column1 rows limit 5 offset 6

Even though you specified a limit of five rows, if table1 has only 10 rows, the output will only have the remaining four rows.

Example 3: Even though you mentioned a limit of five rows, if table1 only has 10 rows, the output will only contain the remaining four rows:

limit = 10;
offset = (limit * pageNumber) - limit;

I've known for a long time that PostgreSQL supports the OFFSET keyword, but for some purpose I always assumed MySQL didn't.

The OFFSET LIMIT clause is an optional clause that allows you to skip a certain number of values from the query before returning the results. The OFFSET LIMIT clause requires both the OFFSET and LIMIT counts.

By doing a pass and picking on the ordered values, the output set is created.

Unless you use ORDER BY to ensure a predictable result ordering, using different LIMIT/OFFSET settings to pick different subsets of a query result will produce inconsistent results. There will be a deterministic order of values if no ORDER BY clause is applied.

If both OFFSET and LIMIT are present, then OFFSET rows are ignored before counting the returning LIMIT rows.

Because the server must still calculate the rows missed by an OFFSET clause, a large OFFSET can be wasteful.

OFFSET indicates how many rows should be skipped before returning to rows. OFFSET 0 is equivalent to leaving the OFFSET clause blank.

If you specify a limit count, only that many rows will be shown (but possibly less, if the query itself yields fewer rows). The LIMIT ALL option is equivalent to missing the LIMIT clause.

It's critical to employ an ORDER BY clause with LIMIT to ensure that the result rows are in a logical order. Instead, a random subset of the query's rows will be returned.

Syntax :

The following shows the syntax of LIMIT & OFFSET clauses:

SELECT 
    column_list
FROM
    table1
ORDER BY column_list
LIMIT row_count OFFSET offset;

In this syntax:

The LIMIT row_count specifies how many rows (row count) the query should provide.

Before returning the rows, the OFFSET offset clause ignores the offset rows.

The OFFSET clause is not required. If you leave it out, the query will output the row_count rows from the first SELECT clause row.

Example 1: The illustration employs both the LIMIT and OFFSET clauses to return five rows, beginning with the 4th row:

SELECT employee_id, 
first_name, last_name
FROM
    employees
ORDER BY first_name
LIMIT 5 OFFSET 3;

Example 2: Here's an instance of a query that ignores the first value and returns the second (in order of resident city_name):

SELECT f.id, f.address.city
FROM Families f
ORDER BY f.address.city
OFFSET 1 LIMIT 1

The value of OFFSET must be zero or larger. An error occurs when a number is negative.

No rows are skipped when OFFSET is 0.

No rows are provided if OFFSET is larger than the number of rows in the ordered outcomes.

Negative OFFSET, which works fine:

SELECT DISTINCT s.* FROM s WHERE ... ORDER BY s.bday ASC, s.name
ASC LIMIT 15 OFFSET -15

When I run the same query on Postgres 9.1, I get an error:

The OFFSET option is used to choose where to begin returning rows from a result. In a SELECT statement or UNION clause, OFFSET must come after the ORDER BY clause. It can not be used independently. The OFFSET specifies how many rows should be skipped before they are included in the result.

Alternatively, an undefined subset of the result set is returned.

When both LIMIT and OFFSET are specified in a SELECT statement or a UNION clause, Vertica evaluates the OFFSET statement first, then performs the LIMIT statement on the remaining data.

Any combination of Sequence BY, OFFSET, and FETCH FIRST clauses can be used in a query, but only in that sequence.

The OFFSET and FETCH FIRST clauses can only be used once per query and are not compatible with unions or view declarations. Except in a CREATE TABLE statement or an INSERT statement, they can't be used in subselects.

The FETCH FIRST clause cannot be combined with the SELECT FIRST rowc_ount clause in the same SELECT statement.

Syntax :

SELECT column-names
  FROM table-name
 ORDER BY column-names
OFFSET n ROWS

Example 1: The general form for the OFFSET argument is:

SELECT   columns
FROM     table
ORDER BY columns OFFSET rows-to-skip ROWS

Values for OFFSET should be zero or higher. An error is produced by a negative number.

There are no rows displayed if OFFSET is higher than the number of rows in the ordered results.

Example 2: List all but 10 of the largest orders, sorted by amount:

SELECT *
  FROM [Order]
 ORDER BY TotalAmount DESC
OFFSET 10 ROWS

Example 3: The following query returns 14 rows from the customer_dimension table:

SELECT customer_name, customer_gender FROM customer_dimension 
WHERE occupation='Dancer' AND customer_city = 'San Francisco' ORDER BY customer_name;

Output:

Example 4: For example, the following query returns rows starting from the 25th row of the result set:

SELECT * FROM MYTABLE ORDER BY COL1 OFFSET 25

On its own, a UNION query relies on the query planner's brains, so you may have to check its plan results to find out (I'm not a PostgreSQL specialist), and it may also depend on the rest of the query information. The output will be the same regardless of how the job is done (which will affect performance); the limitation will be used on the result.

Example 1: In the instance you provided, the UNION query returns a derived table called rs. The limitation will be used throughout the result, in this case, making it functionally equivalent to SELECT * FROM some table > OFFSET 100000 LIMIT 10. You might redo your example as simple as possible because they are similar:

SELECT * FROM rs1
UNION ALL
SELECT * FROM rs2
OFFSET 100000 LIMIT 10;

Example 2:

>@offset INT,
@fetch INT

WITH CTE1
AS
(SELECT TOP 100 PERCENT col1 AS col FROM tab1
UNION
SELECT TOP 100 PERCENT col1 FROM tab2
ORDER BY col OFFSET @offset ROWS FETCH NEXT @fetch ROWS ONLY)

SELECT * FROM CTE1
UNION
SELECT TOP 1 col1 FROM tab3
ORDER BY NEWID()