Retrieving "pages" with some number of rows using SQL - sql

In PostgreSQL: To retrieve 100 rows using an SQL query we can use LIMIT 100.
Is there a way to retrieve first 100 rows and later the next 100 like doing some kind of pagination? i.e.
if I do something like:
SELECT ..... LIMIT 100;
and later execute a command like:
SELECT ... LIMIT 100
I could get the next 100 rows to the previous retrieval of 100 rows and so on?
Thanks in advance

Yes, you need to use limit combined with offset. You can find more details here
select * from table LIMIT 100 OFFSET 100*0 --first 100
select * from table LIMIT 100 OFFSET 100*1 --second 100

Related

How to select rows between x and y in Redshift

I can select the TOP rows from a Redshift table by using the TOP clause. But I would like to select the rows between, say, 10 and 20. I am using the ORDER BY clause, so the resultset is consistent.
How do I do that?
I would ideally like something like:
SELECT * BETWEEN 10 AND 20
FROM <tablename>
The more traditional method in Redshift would be LIMIT/OFFSET. For the second set of 10 rows:
select t.*
from t
order by XXX
limit 10 offset 9;
Note that the offset is one less than the row where you want to start (i.e. offset 0 = "first row").
This is also the syntax used in Postgres.

Know the hidden row in LIMIT sql lite query

I am trying to analyse a sqllite database and I use these data for a bar chart. I will count and do the avg of age group by each value in each column, in this case Class with the limit of only first 100 distinct values.
An example of this table:
Age Class
25 Worker
30 Student
48 Spy
I use LIMIT 100 to limit the result. To add more information for user, I want to let user know the number of values didn't get in account and the hidden rows, is there anyway to achieve this?
Simple solution: I am not very familiar with sql so I think to do two queries, with and without LIMIT, count the number of rows and substrat each other to find the answer. But because I have 42 columns so I would be very happy if I can have another solution.
If you want all but the first 100 rows, you can combine LIMIT with OFFSET.
select * from test01 LIMIT 1000000 OFFSET 100;

PostgreSQL:How get last rows from a select query

See the below example,
create table data(name varchar, value int);
insert into data values('joe',1);
insert into data values('bob',2);
insert into data values('jane',3);
insert into data values('anne',4);
insert into data values('kate',5);
And if I Execute
select * from data limit 2;
Will Get
name | value
------+-------
joe | 1
bob | 2
(2 rows)
So,How Can I Get the Last 2 Rows in select * from data?
What I'm expecting is....
name | value
------+-------
anne | 4
kate | 5
(2 rows)
You have two options according to your need i.e,
select * from data order by value desc limit 2
Or
LIMIT and OFFSET
if you want the 4th and 5th row just offset the first 3 so that the 4th row becomes the start of our set and you can specify a limit to say that you only want 2 rows from that.
select * from data offset 3 limit 2;
/* The order of LIMIT and OFFSET does not matter. This gives the same result */
select * from data limit 2 offset 3;
I know I'm answering a six year old question and I know the accepted answer says to use an offset, however that's only going to be useful if you know the length of the table. Looking at the wording of the question and the example given, I assumed that like myself, the author wanted the last entries in a table based on an id or other value in the order that they were entered.
The best solution I've found so far that orders the values as expected is using a subquery as follows:
SELECT * FROM ( SELECT * FROM data ORDER BY VALUE DESC LIMIT 2) AS _ ORDER BY VALUE ASC;
You'd substitute VALUE for whichever column you'd want to sort by to get the "last" entries. In my experience, this method is an order of magnitude quicker than using a count to find an offset.
To get the x last rows, example with x=10,
use offset alone, with count:
SELECT *
FROM data
ORDER BY value ASC
OFFSET (SELECT count(*) FROM DATA)-10
I let you check if the offset is not negative...
Make use of Order by Clause
select * from data order by value desc limit 2;
OR
select top 2 * from data order by value desc ;
You can achieve it using Order by clause desc
SELECT *
FROM data
ORDER BY value DESC limit 2;
like does Krishraj Rana you can try this function for get the last row with "limit 1" and order by "x col" desc, complete it "by x_col desc limit 1".

SQL - Get next set of xx items

I have a web API that returns the next "set" of x number of items based on the ID of the last item that was recieved. So, if my last item ID was 30, and I want 50 more, then I should get IDs 31 - 81.
If I implement an SQL query that says SELECT * FROM table WHERE ID > 30 LIMIT 50, am I guaranteed to get IDs 31 - 81? Or, is there a way to do that? The ID column is AUTOINCREMENT.
Also, this is SQLite, specifically. I am not sure if that matters.
You should also order them by id before limiting the number of results
SELECT * FROM table WHERE ID > 30
order by ID
LIMIT 50
Usually in SQLite you would do something like this:
SELECT * FROM table LIMIT 50 OFFSET 30;
See http://www.sqlite.org/lang_select.html for documentation.

Is there an alternative to TOP in MySQL?

I want to know the alternative of the TOP keyword as in MySQL. I have read about TOP in SQL Server.
Is there any alternative to this in MySQL, or any other method in MySQL from which we can get same functionality?
Ordering and limiting the results:
SELECT field1, field2
FROM myTable
ORDER BY field1 ASC
LIMIT 10
You can use the LIMIT keyword (See the documentation of the SELECT instruction) -- it goes at the end of the query :
select *
from your_table
where ...
limit 10
to get the top 10 lines
Or even :
select *
from your_table
where ...
limit 5, 10
To get 10 lines, startig from the 6th (i.e. getting lines 6 to 15).
yes, there is the limit clause.
Example:
SELECT * FROM `your_table` LIMIT 0, 10
This will display the first 10 results from the database.
mysql equivalent of top and you can find further more about LIMIT in MySql Doc