Well, i found this simple script online somewhere for selecting the next row and selecting the previous row.
This works. (Next page)
$currentid = $_GET['id'];
$nextquery= mysqli_query($conDB,"SELECT * FROM vids WHERE ID > $currentid ORDER BY ID ASC LIMIT 1")or die (mysqli_error($conDB));
However, this dosent, it returns the current page id instead of the previous id.
What i want is that it gets the last available id that is on the database.
$prevquery= mysqli_query($conDB,"SELECT * FROM vids WHERE ID < $currentid ORDER BY ID desc LIMIT 1")or die (mysqli_error($conDB));
Please someone help me, i would greatly appreciate it! :D
Best regards Dániel
To find the largest value of the field "ID" from the "vids" table, you will want to use the following query:
SELECT ID FROM vids ORDER BY ID DESC LIMIT 1
To find the previous and next rows in the table, the queries you are using look correct, however there appears to be a typo in the first line calculating the $currentid:
$currrentid = $_GET=['id'];
This line should be:
$currrentid = $_GET['id'];
remove DESC for the previous query
"What i want is that it gets the last available id that is on the database."
`SELECT MAX(ID) FROM table_name;`
will give you the last record id in a table.
Next:
select * from table_name where ID = (select min(ID) from table_name where ID > $_GET['id'])
Previous:
select * from table_name where ID = (select max(ID) from table_name where ID < $_GET['id'])
Or you can optimise the query and have it all completed in one call:
select * from table_name where (
ID = IFNULL((select min(ID) from table_name where ID > $_GET['id']),0)
or ID = IFNULL((select max(ID) from table_name where ID < $_GET['id']),0)
)
Related
I have a MySQL table with the columns "user" and "warningpoints" for each warning as you can see in the table above. How can I get the user which has the most warningpoints in total in PHP?
You can use GROUP BY and ORDER BY and LIMIT:
SELECT t.user,sum(t.warningPoints) as sum_points
FROM YourTable t
GROUP BY t.user
ORDER BY sum_points DESC
LIMIT 1;
Or if there is only one record per person, no need to group :
SELECT t.user,t.warningPoints
FROM YourTable t
ORDER BY t.warningPoints DESC
LIMIT 1;
You can simply add below statements in your php code.
$sql = "SELECT User, Max(warningpoints) AS MaxWarningpoints FROM MyGuests GROUP BY User";
$result = $conn->query($sql);
I would like to get number of all records and get last record :
$sql_count_sms = "SELECT count(*) as total,content,id FROM android_users_sms WHERE user_id=$id ORDER BY id DESC";
$result_count_sms = mysql_query($sql_count_sms);
$row_num_sms = mysql_fetch_assoc($result_count_sms);
$num_sms = $row_num_sms['total'];
$last_my_sms = $row_num_sms['content'];
I can get number of records but I can't get last content record .
It returns first record !
Where is my wrong ?
Below codes works fine, but I think count(*) is faster than mysql_num_rows .
$sql_count_sms = "SELECT content,id FROM android_users_sms WHERE user_id=$id ORDER BY id DESC";
$result_count_sms = mysql_query($sql_count_sms);
$row_num_sms = mysql_fetch_assoc($result_count_sms);
$num_sms = mysql_num_rows($result_count_sms);
$last_my_sms = $row_num_sms['content'];
Any solution?
The grain of the two results you want is not the same. Without using a sub-query you can't combine an aggregate and a single row into the same result.
Think of the grain as the base unit of the result. The use of GROUP BY and aggregate functions can influence that "grain"... one result row per row on table, or is it grouped by user_id etc... Think of an aggregate function as a form of grouping.
You could break it out into two separate statements:
SELECT count(*) as total FROM android_users_sms WHERE user_id = :id;
SELECT * FROM android_users_sms WHERE user_id = :id ORDER BY id DESC LIMIT 1;
Also, specific to your question, you probably want a LIMIT 1 in combination with the ORDER BY to get just the last row.
Now, counter intuitively perhaps, this should also work:
SELECT count(*), content, id
FROM android_users_sms
WHERE user_id = :id
GROUP BY id, content
ORDER BY id
LIMIT 1;`
This is because we've changed the "grain" with the GROUP BY. This is the real nuance and I feel like this could probably be explained better than I am doing now.
You could also do this with a sub query like so:
SELECT aus.*,
(SELECT count(*) as total FROM android_users_sms WHERE user_id = :id) AS s1
FROM android_users_sms AS aus
WHERE user_id = :id ORDER BY id DESC LIMIT 1;
My table structure is
I want to get the recent video uploaded of the user
What I want to do is:
"select video_id of a record who is having minimum of timestamp where userid='something'"
What I currently have is:
$recent_video = "$db->query("
SELECT video_id
FROM video_primary
ORDER BY timestamp DESC LIMIT 1
WHERE userid = '$userid'"
) or die($db->error);"`
while($row=mysqli_fetch_assoc($recent_video))
{
$video_id=$row['video_id'];
}
echo $video_id;
My table data is
How do I get the most recent view uploaded by the user?
Write WHERE clause after FROM part
Try this:
SELECT vp.video_id
FROM video_primary vp
WHERE userid='$userid'
ORDER BY vp.timestamp DESC
LIMIT 1;
try this
$recent_video=$db->query("select video_id from video_primary where userid='$userid'
ORDER BY timestamp DESC LIMIT 1 ") or die($db->error);
instead of
$recent_video="$db->query("select video_id from video_primary ORDER BY timestamp DESC
LIMIT 1 where userid='$userid'") or die($db->error);"
you are using where clause after order by and limit 1 which is a syntax error. see tutorial
Tutorial
There is a specific sequence of every clause in Query statement. Below is the sequence:
Select
Where
Order by
Limit
So, as per the above sequence, you should correct your query like below. Also, you should place double quote(") correctly.
$recent_video = $db->query("
SELECT video_id
FROM video_primary
WHERE userid = '$userid'
ORDER BY timestamp DESC LIMIT 1"
) or die($db->error);
I'm trying to keep the 10 most recent entries in my database and delete the older ones. I tried DELETE FROM people ORDER BY id DESC LIMIT $excess, but it just deleted the top 10 entries.
$query = "SELECT * FROM people";
$result = mysqli_query($conn, $query);
$count = mysqli_num_rows($result);
if ($count > 10) {
$excess = $count - 10;
$query = "DELETE FROM people WHERE id IN(SELECT id FROM people ORDER BY id DESC LIMIT '$excess')";
mysqli_query($conn, $query);
}
You can use this:-
DELETE FROM `people`
WHERE id NOT IN (
SELECT id
FROM (
SELECT id
FROM `people`
ORDER BY id DESC
LIMIT 10
)
);
Also your query is logically incorrect and you are fetching the records in descending order. i.e. Latest to older and you are deleting the most recent records. Use ASC instead.
Something like this? Gets the ten latest ids in the subquery, then deletes all of the other ids.
DELETE FROM people WHERE id NOT IN (SELECT id FROM PEOPLE ORDER BY id DESC LIMIT 10)
Your logic is all over the place, [you should ORDER BY ASC, not DESC] and your query will take ages if there are [for example] 10,000 entries because you'll have an IN clause with 9,990 entries to compare all 10,000 to.
Select the 10 most recent, and delete where NOT in.
DELETE FROM people
WHERE id NOT IN(
SELECT id
FROM people
ORDER BY id DESC
LIMIT 10
)
Maybe find the ID of the 10th element and then delete all rows which are older?
I am looking for a better way of doing this:
SELECT * FROM $tbl_name WHERE id >= (SELECT FLOOR( MAX(id) * RAND()) FROM $tbl_name ) ORDER BY id LIMIT 1;
It is slow and isn't very random, I get the same result every 10 or so query's.
This selects a random row from the table regardless of its ID.
So far I have this:
// Get amount of rows in database
$result = mysql_query("SELECT * FROM $tbl_name");
$num_rows = mysql_num_rows($result);
// Generate random number
$random_row = rand(1, $num_rows);
But I don't know how to get a certain row.
I do not mean
SELECT * FROM $tbl_name WHERE id = $random_row
Because my database has gaps in the ID column so it would sometimes fail.
Has anyone got script that can get a random result from a MySQL database without replying on IDs and is super fast? (the database contains about 20000 rows)
SELECT * FROM $tbl_name WHERE 1 ORDER BY RAND() LIMIT 1;
20,000 rows isn't really that much, the above should be fast enough.
Juhana is right by the book: "ORDER BY RAND() LIMIT 1", and of course 20k isn1t that much.
Other option will be with subselects:
SELECT [fields]
FROM myTable,
(SELECT FLOOR(MAX(myTable.id) * RAND()) AS randId FROM myTable) AS someRandId
WHERE myTable.id = someRandId.randId
discussed here
(please avoid select * when it`s unnecessary)
After some searching though the comments on the link Adi sent, I have found a decent solution.
SELECT * FROM $tbl_name T JOIN (SELECT CEIL(MAX(ID)*RAND()) AS ID FROM $tbl_name) AS x ON T.ID >= x.ID LIMIT 1;
Source: wanderr.com/jay/order-by-slow/2008/01/30
Seems to be very fast and very random!