I want to select last 3 rows of my table and no id is defined and table is not sorted either. Put it this way without using order clause or I just want to reverse the records of my non ordered table.
Try this -
SET #rownum:=0;
SELECT *
FROM (SELECT #rownum:=#rownum+1 as rownum,*
FROM yourTable) t1
ORDER BY rownum DESC
LIMIT 3;
Related
I was wondering how to grab the first item and the last item in a MySQL database. I know these two lines will do the work, but I am trying to limit it down to one line.
SELECT * FROM `test_table` order by ID asc limit 0,1
SELECT * FROM `test_table` order by ID desc limit 0,1
For example there is a table called test_table and it has 5 rows. I would like to get row number 1 and row number 5 in the same statement. This will save me from using many PHP if statements and will shorten up my code. Any help would be appreciated.
The following SQL does not get the first item:
SELECT * FROM `test_table` limit 0,1
It returns an arbitrary row. SQL tables and result sets are unordered, so limit without order by returns an indeterminate row.
The syntax to do what you want is:
(SELECT t.* FROM `test_table` t ORDER BY id ASC LIMIT 1)
UNION ALL
(SELECT t.* FROM `test_table` t ORDER BY id DESC LIMIT 1);
Note: If the table has only one row, this returns two rows, because the same row is the "first" and "last". If you want only one in this situation, you could use UNION rather than UNION ALL.
use union it will combine both sql queries and you the expected result
SELECT * FROM `test_table` limit 0,1
union
SELECT * FROM `test_table` order by ID desc limit 0,1
You can use the min and max ID if it's monotonically increasing -
SELECT * FROM `test_table`
WHERE ID IN ((SELECT MIN(ID) FROM `test_table`), (SELECT MAX(ID) FROM `test_table`));
I'd suggest running the explain for the query to see if it performs as per your expectation.
I have a mysql query which will return all the details from table along with i need max_row count i.e total no of rows in a table using COUNT(*) in a single select query without using cross join.
Note: MySQL version is earlier version of 8
Query :
SELECT * FROM tablename ORDER BY column name DESC LIMIT 0,10;
The total count of a table is simple, when you want to add it to every row.
SELECT
*
,(SELECT COUNT(*) FROM tablename ) count1
FROM tablename
ORDER BY column name
DESC LIMIT 0,10;,
I want to select last 50 rows from MySQL database within column named id which is primary key. Goal is that the rows should be sorted by id in ASC order, that’s why this query isn’t working
SELECT
*
FROM
`table`
ORDER BY id DESC
LIMIT 50;
Also it’s remarkable that rows could be manipulated (deleted) and that’s why following query isn’t working either
SELECT
*
FROM
`table`
WHERE
id > ((SELECT
MAX(id)
FROM
chat) - 50)
ORDER BY id ASC;
Question: How is it possible to retrieve last N rows from MySQL database that can be manipulated and be in ASC order ?
You can do it with a sub-query:
SELECT * FROM
(
SELECT * FROM table ORDER BY id DESC LIMIT 50
) AS sub
ORDER BY id ASC;
This will select the last 50 rows from table, and then order them in ascending order.
SELECT * FROM table ORDER BY id DESC LIMIT 50
save resources make one query, there is no need to make nested queries
SELECT * FROM table ORDER BY id DESC, datechat DESC LIMIT 50
If you have a date field that is storing the date (and time) on which the chat was sent or any field that is filled with incrementally (order by DESC) or de-incrementally (order by ASC) data per row put it as second column on which the data should be ordered.
That's what worked for me!!!! Hope it will help!!!!
Use it to retrieve last n rows from mysql
Select * from tbl order by id desc limit 10;
use limit according to N value.
if anyone need this
you can change this into
SELECT
*
FROM
`table`
WHERE
id > ((SELECT
MAX(id)
FROM
chat) - 50)
ORDER BY id ASC;
into
SELECT
*
FROM
`table`
WHERE
id > (SELECT MAX(id)- 50 FROM chat)
ORDER BY id ASC;
select * from Table ORDER BY id LIMIT 30
Notes:
* id should be unique.
* You can control the numbers of rows returned by replacing the 30 in the query
How would I do something like this?
SQL SELECT row FROM table WHERE id=max(id)
You could use a subselect:
SELECT row
FROM table
WHERE id=(
SELECT max(id) FROM table
)
Note that if the value of max(id) is not unique, multiple rows are returned.
If you only want one such row, use #MichaelMior's answer,
SELECT row from table ORDER BY id DESC LIMIT 1
You could also do
SELECT row FROM table ORDER BY id DESC LIMIT 1;
This will sort rows by their ID in descending order and return the first row. This is the same as returning the row with the maximum ID. This of course assumes that id is unique among all rows. Otherwise there could be multiple rows with the maximum value for id and you'll only get one.
SELECT *
FROM table
WHERE id = (SELECT MAX(id) FROM TABLE)
You can not give order by because order by does a "full scan" on a table.
The following query is better:
SELECT * FROM table WHERE id = (SELECT MAX(id) FROM table);
One can always go for analytical functions as well which will give you more control
select tmp.row from ( select row, rank() over(partition by id order by id desc ) as rnk from table) tmp where tmp.rnk=1
If you face issue with rank() function depending on the type of data then one can choose from row_number() or dense_rank() too.
Try with this
SELECT top 1 id, Col2, row_number() over (order by id desc) FROM Table
How can I select the row with the highest ID in MySQL? This is my current code:
SELECT * FROM permlog WHERE max(id)
Errors come up, can someone help me?
SELECT * FROM permlog ORDER BY id DESC LIMIT 0, 1
if it's just the highest ID you want. and ID is unique/auto_increment:
SELECT MAX(ID) FROM tablename
For MySQL:
SELECT *
FROM permlog
ORDER BY id DESC
LIMIT 1
You want to sort the rows from highest to lowest id, hence the ORDER BY id DESC. Then you just want the first one so LIMIT 1:
The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement.
[...]
With one argument, the value specifies the number of rows to return from the beginning of the result set
SELECT *
FROM permlog
WHERE id = ( SELECT MAX(id) FROM permlog ) ;
This would return all rows with highest id, in case id column is not constrained to be unique.
SELECT MAX(id) FROM TABLENAME
This identifies the largest id and returns the value
Suppose you have mulitple record for same date or leave_type but different id and you want the maximum no of id for same date or leave_type as i also sucked with this issue,
so Yes you can do it with the following query:
select * from tabel_name where employee_no='123' and id=(
select max(id) from table_name where employee_no='123' and leave_type='5'
)
SELECT MAX(ID) FROM tablename LIMIT 1
Use this query to find the highest ID in the MySQL table.
Since both SELECT MAX(id) FROM table and SELECT id FROM table ORDER BY id DESC LIMIT 0,1 fulfill the goal, the interesting part is, which performs better.
SELECT MAX(id) FROM table: 152ms
SELECT id FROM table ORDER BY id DESC LIMIT 0,1: 25ms
(InnoDB-table with 55M rows on MySQL 8.0, 10 runs, average result)
Of course thats not representive, but gives an idea, that the ORDER BY method performs significantly better.
This is the only proposed method who actually selects the whole row, not only the max(id) field. It uses a subquery
SELECT * FROM permlog WHERE id = ( SELECT MAX( id ) FROM permlog )
SELECT * FROM `permlog` as one
RIGHT JOIN (SELECT MAX(id) as max_id FROM `permlog`) as two
ON one.id = two.max_id