How can I select latest row from by table without sorting it?
It is because it follow by the ID AUTO INCREMENT...
I'm using c# asp.net to select... I did try using LIMIT 5 but it give me an error page..
rSQL = "select COUNT(*) from chatLog_db where sessionid='" + grpID + "' LIMIT 5";
Is there any better way to solve this matter?
I'd appreciate any help please.
You have an id column which is autoincremented, right? Then you can do it like this..
select * from tablename where id=(select MAX(rid) from tablename)
On MSSQL simply use the top 1 instead of limit
select top(1) * from mytable order by some_column
http://msdn.microsoft.com/en-us/library/ms189463.aspx
if the latest means the max id
select * from chatLog_db
where id = (select max(id) from chatLog_db);
EDIT
select 5 records
select * from chatLog_db
where id > (select max(id) - 5 from chatLog_db);
You can try
SELECT * FROM chatLog_db WHERE sessionid > (SELECT MAX(sessionid) - 1 FROM chatLog_db);
You may also try for
SELECT * FROM chatLog_db WHERE sessionid > (SELECT MAX(sessionid) - 5 FROM chatLog_db);
You may use max as well like
select * from chatLog_db where sessionid = (select max(sessionid) from chatLog_db);
Something like that.
If you are not using order by into your query because you are thinking that it will change the order of your dsplay data then i will tell you that there is one trick as well to sort your data as per your need
you can also sort your data as per your need even if you are using
order by into your query,put the result into DataView and sort it
according to your need because DataView allow us sorting facility as
well.
Latest by using Order By like
select * from tablename order by columnname desc LIMIT 5;
Hope it works for you.
Related
I would like to use the LIMIT option in my query, but the number of expected rows is stored in another table. This is what I have, but it doesn't work:
select * from table1 limit (select limitvalue from table2 where id = 1)
When I only run the subquery, the result is 6, as expected.
I prefer working with a WITH statement if possible, but that didn't work eiter.
Thank you in advance!
You could use a prepared statement to get the limit of queries from the other table because the limit clause does not allow non constant variables as parameter:
PREPARE firstQuery FROM "SELECT * FROM table1 LIMIT ?";
SET #limit = (select limitvalue from table2 where id = 1);
EXECUTE firstQuery USING #limit;
The source of the sql query from another post
You can make use of MariaDB's ROW_NUMBER function in a CTE to count the rows to be output, comparing that against the limitvalue. For example:
WITH rownums AS (
SELECT *,
ROW_NUMBER() OVER () AS rn
FROM table1
)
SELECT *
FROM rownums
WHERE rn <= (SELECT limitvalue FROM table2 WHERE id = 1)
Note Using LIMIT without ORDER BY is not guaranteed to give you the same results every time. You should include an ORDER BY clause in the OVER part of the ROW_NUMBER window function. With the sample data in my demo, you might use something like:
ROW_NUMBER() OVER (ORDER BY mark DESC)
Demo on dbfiddle
here is my query
select *
from table
where id in ( select string_agg(CAST(id as varchar), '","') FROM table)
string_agg() is completely useless and unnecessary for that:
select *
from table_one
where id in (select id FROM other_table)
I assume you are doing that for two different tables, otherwise that would be a very expensive way of writing: select * from table where id is not null
My current query:
select timestamp from messagesTable
where partner_jid='" + lastUserJid + "' AND msg='.roll'
order by timestamp DESC LIMIT 1 OFFSET 1;
This works fine... unless the values don't exist in the database.
If values do not exist in database, then it should Select * messagesTable; or do nothing if possible.
Is there a way to add a check for that within the same query? It has to be the same query unfortunately because I need to execute things through adb shell. I've been trying things out with CASE but I do not really understand much about SQL.
You can just append a second query, with a WHERE filter that checks whether the first query did not return anything:
SELECT *
FROM (SELECT timestamp
FROM messagesTable
WHERE partner_jid = ?
AND msg = '.roll'
ORDER BY timestamp DESC
LIMIT 1 OFFSET 1)
UNION ALL
SELECT -1 -- or "timestamp FROM msgTab", or whatever
WHERE NOT EXISTS (SELECT timestamp
FROM messagesTable
WHERE partner_jid = ?
AND msg = '.roll');
I have a problem with this query I want retrieve all records but leaving first twenty,
Error is: {"Incorrect syntax near 'LIMIT'."}
"SELECT * FROM [upload_news] WHERE [country]='" + country.Text + "' ORDER BY [upload_time] DESC LIMIT 20";
You can't use LIMIT with SQL Server. You can use Top 20. Or you can use ROW_NUMBER and then filter based on that.
Also you should parametrized your query, your current query is prone to SQL Injection.
using (SqlCommand cmd = new SqlCommand(#"SELECT TOP 20 *
FROM [upload_news]
WHERE [country]=#country ORDER BY [upload_time] DESC", connection))
{
cmd.Parameters.AddWithValue("#country", country.Text);
//,.... rest of the code
}
If it's SQL Server, you need to use Top N.
SELECT TOP 20 * FROM [upload_news] WHERE [country]='" + country.Text + "'
ORDER BY [upload_time] DESC
if you want to retrieve all records but leaving first twenty
using this Query
select * from(SELECT (ROW_NUMBER() OVER (ORDER BY upload_time desc)) AS rowNum,*
FROM [upload_news])as temp where temp.rowNum >20
please tell me if it worked
I have a table with three columns as follows:
id INTEGER name TEXT value REAL
How can I select the value at the maximum id?
Get the records with the largest IDs first, then stop after the first record:
SELECT * FROM MyTable ORDER BY id DESC LIMIT 1
Just like the mysql, you can use MAX()
e.g. SELECT MAX(id) AS member_id, name, value FROM YOUR_TABLE_NAME
Try this:
SELECT value FROM table WHERE id==(SELECT max(id) FROM table));
If you want to know the query syntax :
String query = "SELECT MAX(id) AS max_id FROM mytable";