I have a table with 116,000 rows and I want to retrieve all of these rows but in 3 separate queries using:
"SELECT * FROM table LIMIT 0, 50000"
"SELECT * FROM table LIMIT 1, 50000"
"SELECT * FROM table LIMIT 2, 50000"
I have tried this but all the queries return a result of 50,000 rows, even if the "LIMIT is 10, 50000" there is a result which is not what I want. I am only expecting 16,000 rows for the 3rd query.
How can I accomplish this? Is my expectation of LIMIT pagination wrong?
Your expectation of how LIMIT works is wrong. The first parameter is the first record to fetch, and the second parameter is the number of records to fetch.
For example, if a query has 800 results and you use LIMIT 100, 300 you will get the 100th to 400th rows, totalling 300 rows.
Go to http://dev.mysql.com/doc/refman/5.0/en/select.html and search for "The LIMIT clause" to read more about how LIMIT works.
The first argument to LIMIT is the starting record number, not the starting page number. Your limits in this case should be:
"SELECT * FROM table LIMIT 0, 50000" # 50,000 records starting at the 0th record
"SELECT * FROM table LIMIT 50000, 50000" # 50,000 records starting at the 50000th record
"SELECT * FROM table LIMIT 100000, 50000" # 50,000 records starting at the 100000th record
It's LIMIT offset, rowcount. Your first query fetches 50,000 rows, starting at row 0. Your second query fetches 50,000 rows, starting at row 2. In other words, you're fetching 49,999 same rows, and then one different.
If you want to split your 116,000 rows into 3 equal parts, you'd have to do
SELECT ... LIMIT 0, 38666
SELECT ... LIMIT 38667, 38666
SELECT ... LIMIT 77333, 38668
Limit clause takes one or two arguments:
the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return. The offset of the initial row is 0 (not 1).
So you can do:
select * from table limit 0,50000;
select * from table limit 50001,50000;
select * from table limit 100001,50000;
Take a look at this link
Yes, you're understanding is wrong. You should do
SELECT * FROM table LIMIT 100000, 50000
. The syntax is either
SELECT [..] LIMIT <count>
or
SELECT [..] LIMIT <offset>, <count>
. Whereas everything is relative to the number of rows SELECTed.
Related
This might be a very basic question but I am struggling with queying the specific rows in a table based only on the row range.
Let's say I have a table ABC where I have populated 1000 rows. Now I want a sql query so that I can fetch first 100 rows ( that is the range 1 to 100) and then the next 100 ( 101 to 200) and so on till I am done with all rows. And this should be done without querying/filtering on the table's id or any column id.
I am not able to figure it out as I am trained only on querying specific columns in WHERE clause so would appreciate if someone can plz help
You have to use the LIMIT clause in the SELECT query. MySQL allows you to set two parameters for the clause, the offset (first parameter) and the number of rows to fetch (second parameter).
SELECT * FROM `ABC` LIMIT 0, 100
SELECT * FROM `ABC` LIMIT 100, 100
SELECT * FROM `ABC` LIMIT 200, 100
-- etc...
However, you cannot guarantee the order of these rows unless you sort by one or more specific column(s) using the ORDER BY clause.
Read more about the SELECT statement here: http://dev.mysql.com/doc/refman/5.6/en/select.html
you can use limit in mysql.
limit accept 2 parameters.
this will return 1-10 records.
select * from abcd limit 10
this will return 10-20 records.
select * from abcd limit 10,10
this will return 20-30 records.
select * from abcd limit 20,10
Let say I retrieve my list of data...
First
$Query = mysql_query("SELECT * FROM data ORDER BY name ASC LIMIT 0,30");
From there I am using AJAX/jQuery to to append an additional 30 records. Which I need to call another file where the query will pick up where I left off.
Second
$Query = mysql_query("SELECT * FROM data WHERE name < '".mysql_real_escape_string($_GET['lastRecord'])."' ORDER BY name ASC LIMIT 0,30");
My question is, if I have the first query order the first 30 by name, how can I write the second query to pick up where I left off in that order?
Change the LIMIY like this - LIMIT 30, 30
BTW, you tagged this as jQuery and it isn't.
This option is good for short tables, but in a long tables this will give bad performance.
Every query (like that) you execute will do full table scan with filesort which takes some time.
I think you need to read the table once, and put the result in a temporary table (already sorted) with some index column and then use WHERE index BETWEEN $number AND ($number+30).
You don't need to add a WHERE clause to your query, you just need to use LIMIT to slice out the chunks of results you want. Limit is used to limit your MySQL query results to those that fall within a specified range. You can use it to show the first X number of results, or to show a range from X - Y results. The syntax is Limit X, Y where X is the starting point and Y is the number of records to retrieve.
For example:
$Query = mysql_query("SELECT * FROM data ORDER BY name ASC LIMIT 90,30");
would retrieve 30 records beginning with the 91st (records are zero indexed).
The first number in the LIMIT clause is the offset, starting at 0. So, your first query is correctly LIMIT 0, 30 to get the first 30.
Simply increase the offset by 30 to start at record 31, so to get 30 more do LIMIT 30, 30.
For the third page, it would be LIMIT 60, 30, etc.
If you need a page x of n type display, issue a COUNT(*) first to get the total number of rows, but understand that the actual rows and row count may change if rows are being inserted or deleted between calls.
Is there a way to grab an exact amount of entries from a database example. For example say you had a table that just had an id and total visits for the columns. Say you wanted to grab exactly 20 entries and sort them by total visits. How would you go about this? I know how to sort the whole table, but would like to be able to grab the top twenty total visits and then sort them. Thanks
O and right now I am using sqlite, but I know in the future I will be using mysql also. Thanks
Try with:
SELECT * FROM TableName ORDER BY TotalVisits LIMIT 20
using limit to get the top 20,
and if you want to add another sort, add it after visit column
like :
SELECT * FROM mytable ORDER BY visits DESC
/*here put another order by field like date */
, date
LIMIT 20
Use ORDER - LIMIT clause
SELECT * FROM table ORDER BY field [ASC|DESC] LIMIT 20 OFFSET [offset value]
You need to use LIMIT, but you will need to put the whole thing in a subquery if you intend to re-sort the top 20 based on separate criteria. So
SELECT * from <table> order by <total visits column> LIMIT 20
will get you the top 20, but then to sort within that result you would do something like
SELECT * from
(SELECT * from <table> ORDER BY <total visits column> LIMIT 20)
ORDER BY <other criteria>
The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants, with these exceptions:
With two arguments, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return. The offset of the initial row is 0 (not 1):
SELECT * FROM tbl LIMIT 5,10; # Retrieve rows 6-15
To retrieve all rows from a certain offset up to the end of the result set, you can use some large number for the second parameter. This statement retrieves all rows from the 96th row to the last:
SELECT * FROM tbl LIMIT 95,18446744073709551615;
With one argument, the value specifies the number of rows to return from the beginning of the result set:
SELECT * FROM tbl LIMIT 5; # Retrieve first 5 rows
In other words, LIMIT row_count is equivalent to LIMIT 0, row_count.
All on: http://dev.mysql.com/doc/refman/5.5/en/select.html better explnation for mysql, however sqlite works same way: http://www.sqlite.org/lang_select.html
Is there a way in MySQL to have the first 10 result from a SELECT query skipped?
I'd like it to work something like LIMIT.
Use LIMIT with two parameters. For example, to return results 11-60 (where result 1 is the first row), use:
SELECT * FROM foo LIMIT 10, 50
For a solution to return all results, see Thomas' answer.
There is an OFFSET as well that should do the trick:
SELECT column FROM table
LIMIT 10 OFFSET 10
OFFSET is what you are looking for.
SELECT * FROM table LIMIT 10 OFFSET 10
From the manual:
To retrieve all rows from a certain offset up to the end of the result set, you can use some large number for the second parameter. This statement retrieves all rows from the 96th row to the last:
SELECT * FROM tbl LIMIT 95,18446744073709551615;
Obviously, you should replace 95 by 10. The large number they use is 2^64 - 1, by the way.
LIMIT allow you to skip any number of rows. It has two parameters, and first of them - how many rows to skip
To skip first 10 rows use OFFSET 10, but LIMIT is also required,
If you want to get all the rows and only skip first 10 rows try using a big number like 999999999 or as per your choice
SELECT * FROM table LIMIT 999999 OFFSET 10
select * from table where id not in (select id from table limit 10)
where id be the key in your table.
If your table has ordering by id, you could easily done by:
select * from table where id > 10
for example will select * from table limit 0,5 return at most 5 rows or must it find exactly 5 and if the row_count doesnt equal 5, it returns an empty result set?
what if the query was select * from table limit 5?
http://dev.mysql.com/doc/refman/5.1/en/select.html
"The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be non-negative integer constants (except when using prepared statements).
With two arguments, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return."
So, to answer your question directly, it would return at most 5 rows.
Query SELECT * FROM table LIMIT 0,5 will return 5 records starting from the first record.
Query SELECT * FROM table LIMIT 5 will also give the same result as above query.
If in that table there are fewer than 5 records then it will not fail but return whatever records are there.
Query SELECT * FROM table LIMIT 6,5 will return record 7,8,9,10,11 as the index starts from 0.
The limit is, well, a limit, so it won't return more than that many rows. It can return less.
In query "select * from table limit 0,5"
0 does not specify the minimum records to return. It specifies the OFFSET. So when you say 0, if the query "select * from table" returns 10 records, "limit 0,5" will return the first 5. If you use "limit 5,5" it will return last 5 records.
If you have only 2 records, it will return two records. It will not return an error if you have no results. LIMIT is the maximum limit. Minimum can be anything, even 0 records.
"select * from table limit 5" is the same as "select * from table limit 0,5"