I need to write a query to retrieve values from two columns using mysql table
My table has the following strucutre
| ID | user_id | datetime | message |
| 1 | 21 | 2012-05-10 04:13:01 | message1 |
| 2 | 07 | 2012-05-10 04:17:51 | message2 |
| 3 | 21 | 2012-05-11 04:21:51 | message3 |
| 4 | 21 | 2012-05-11 04:43:51 | message4 |
| 5 | 07 | 2012-05-11 04:21:51 | message5 |
| 5 | 21 | 2012-05-11 04:43:51 | message6 |
i wrote the below query
$query="SELECT MAX(datetime) FROM messages where user_id=21 and date=2012-05-11";
but i am not getting latest record from table iam getting null value
help us
$query="SELECT MAX(datetime) FROM messages where user_id=21 and date LIKE '2012-05-11%'";
You should use DATE(date) to get date of timestamp. MySQL function DATE() extracts only date without hours, minutes and seconds.
Here is your query:
SELECT MAX(datetime)
FROM messages
WHERE user_id = 21 AND DATE(date) = '2012-05-11'
Have you tried the following?
$query="SELECT MAX(datetime) FROM messages where user_id=21";
Update:
In your question, you didn't specify if you wanted to retrieve last record for a certain date. If you do, you'd need to use MySQL's date function.
Are you looking for the most recent record? You can get this with a subquery:
$query = "SELECT * FROM messages WHERE datetime = (SELECT MAX(datetime) FROM messages)";
Your query asks for ".....date=2012-05-11";" but your table does not have the field named date? did you mean datetime? if so, you may want to try ".....datetime like '2012-05-11%'";
Related
Example my_table
ID | Name | Date
--------------------------
12 | John | 123456789
13 | Mike | 987654321
...
29 | Rick | 123498765
30 | Adam | 987651234
show output result like this
Month | Count
--------------------------
3 | 5 |
6 | 8 |
How can I do this with PHP?
You can do this using MySQL Query as below.
SELECT MONTH(FROM_UNIXTIME(`Date`)) `Month`
,COUNT(ID)
FROM my_table
GROUP BY `Month`;
Since post tagged codeigniter
This is codeigniter way:
$query = $this->db->select("month(from_unixtime(`Date`)) as `month`, count(1) as `count`",FALSE)
->group_by("month");
->get("your_table");
I'm struggling on how to write this query and cant quite find an answer to help me with my case.
Consider the following table:
-----------------------------------------------
| ID | Value1 | Value2 | Value3 | Date |
-----------------------------------------------
| 1 | 10 | 23 | 30 | 2015-01-01 |
-----------------------------------------------
| 1 | 11 | 33 | 40 | 2015-02-01 |
-----------------------------------------------
| 2 | 26 | 93 | 20 | 2015-01-01 |
-----------------------------------------------
| 2 | 11 | 33 | 50 | 2015-02-01 |
-----------------------------------------------
I want to retrieve the average value of Value1 where the Date is 2015-01-01
I thought that
SELECT AVG(PAM_1) FROM MyTable WHERE DATE = 2015-01-01
would work but of course it does not. I'm aware that I probably need to use HAVING but I'm being confused if I must also use GROUP BY and if do I need the AS (something) part.
EDIT
The problem was not related to the query. I was supplying the date trough a variable as such:
$sth = $db->prepare("SELECT AVG(Value1) FROM MyTable WHERE DATE = $date");
Which is not possible to do with prepared statements.
Your query is basically fine. Your date constant is not. Dates constants should be enclosed in single quotes:
SELECT AVG(PAM_1)
FROM MyTable
WHERE DATE = '2015-01-01';
If the date could have a time component, then the following is the best way to handle this:
SELECT AVG(PAM_1)
FROM MyTable
WHERE DATE >= '2015-01-01' AND DATE < '2015-01-02';
Okay guys I have big problem with mySQL. I need to to do select that gets the free tables in the restaurant in specific time. Here are my tables:
tables:
+-------------+
| id | chairs|
+-------------+
| 1 | 3 |
| 2 | 5 |
| 4 | 10 |
| 7 | 12 |
| 10 | 6 |
+-------------+
and reservations:
+---------------------------------+
| id | table_id | start_datetime |
+----------------|---------------------+
| 1 | 3 | 2013-11-27 16:15:00 |
| 2 | 5 | 2013-11-27 19:00:00 |
+----------------|---------------------+
I try something like this
SELECT *
FROM wp_reserveit_tables,wp_reserveit_reservations
WHERE (wp_reserveit_tables.chairs = wp_reserveit_reservations.table_id
AND wp_reserveit_reservations.start_datetime - INTERVAL 1 HOUR >= '2013-11-29 16:15:00'
AND wp_reserveit_reservations.start_datetime + INTERVAL 1 HOUR <= '2013-11-29 16:15:00')
OR wp_reserveit_tables.chairs <> wp_reserveit_reservations.table_id
but it gives me SQL error.
So please if you have and idea please write it down.
Thanks
Reservation table will have entry only if there are any reservations. So we can do it simply with NOT IN clause I guess,
SELECT * FROM wp_reserveit_tables WHERE chairs_id NOT IN
(SELECT table_id FROM wp_reserveit_reservations GROUP BY table_id)
In your query you have joined them with chairs column with table_id column. So am not sure which one matches. So please alter the column in Where clause as per your requirement.
You have column name start_datetime in your query and your table structure specifies it to be starttime.
Unless you specify further, this does look like a valid error if it is not a typo.
I can code in PHP but I'm not good with SQL at all. I need to run an update on a table in order to pass in a given user_id and set the "access_end" date for all products the user owns to one year from today's date.
Any help much appreciated
Database is MySQL
Table name is dap_users_products_jn
Relevant Fields in database are:
user_id | access_end_date | product_id
1 | 2012-10-26 | 34
1 | 2012-11-21 | 30
1 | 2012-12-22 | 3
2 | 2012-10-20 | 34
2 | 2012-07-18 | 30
2 | 2012-08-15 | 3
...etc
update dap_users_products_jn
set access_end_date = date_add(now(), interval 1 year)
where user_id = 1
MYSQL Table trial_list structure as follows...
id | product_id | expiry_date(date) | by_user | curr_datentime(timestamp)
we are able to extend any trial, and if we do that it simply another row with new expiry_date.
Now we would like to get rows got expired yesterday, we are currently using following sql query.....
Sample MYSQL DATASET
+----+-------------+-------------+-------------+----------+---------------------+
| id | product_id | comment | expiry_date | by_user | dnt |
+----+-------------+-------------+-------------+----------+---------------------+
| 2 | 50 | testing | 2011-02-18 | tester | 2011-02-17 23:36:12 |
+----+-------------+-------------+-------------+----------+---------------------+
| 3 | 50 | again | 2011-02-20 | tester | 2011-02-19 20:36:12 |
+----+-------------+-------------+-------------+----------+---------------------+
| 4 | 50 | extend | 2011-02-23 | tester | 2011-02-21 22:36:12 |
+----+-------------+-------------+-------------+----------+---------------------+
$sql = 'SELECT id, product_id, expiry_date, by_user, curr_datentime FROM trial_list WHERE expiry_date < CURDATE() ORDER BY expiry_date DESC';
We believe this is not correct as its getting all rows which date is older than yesterday not updated expiry_date, suppose we have given some user expiry date 1st feb 2011 and then we change again with 12th feb 2011, so it selects 1st feb 2011 entry. I think it makes sense.
What you have to do first is get the latest item per product_id. After that you can further filter it down to those which are expired. Something like:
SELECT a.* FROM
trial_list AS a
LEFT JOIN trial_list AS b ON a.product_id = b.product_id AND a.id < b.id
WHERE b.product_id IS NULL
AND a.expiry_date < curdate()
See http://dev.mysql.com/doc/refman/5.5/en/example-maximum-row.html
Try using NOW() instead of CURDATE(), you are comparing a Date to a Timestamp, NOW() will compare timestamps.