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MySQL - Selecting rows with a minimum number of occurences


MySQL - Selecting rows with a minimum number of occurences

By : Michael Salonius
Date : November 20 2020, 07:00 PM
I hope this helps . I have this query: , Something like this (off-the-cuff and untested):
code :


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How can I create a MySQL JOIN query for only selecting the rows in one table where a certain number of references to tha

How can I create a MySQL JOIN query for only selecting the rows in one table where a certain number of references to tha


By : Lee Lawmaster
Date : March 29 2020, 07:55 AM
it should still fix some issue I have two tables in my database, called ratings and movies. , Use the HAVING clause. Something along these lines:
code :
SELECT movies.id, movies.title, COUNT(ratings.id) AS num_ratings 
  FROM movies 
  LEFT JOIN ratings ON ratings.movie_id=movies.id 
  GROUP BY movies.id 
  HAVING num_ratings > 5;
MySQL: Selecting rows greater than a random number is producing strange results

MySQL: Selecting rows greater than a random number is producing strange results


By : Andrew Paris Nguyen
Date : March 29 2020, 07:55 AM
To fix this issue Suppose one has a table of 1000 entries. We want to pick a random number between 1 and 1000 and return all rows with an id greater than or equal to that value. It appears to work just fine when entering a static value. For example , This is why your random changes....
code :
  mysql> select id,rand() from test_big;
    +-------------+----------------------+
    | id          | rand()               |
    +-------------+----------------------+
    |          10 |   0.9478371384999129 |
    |          11 | 0.024267499357711057 |
    |   123456789 |   0.2778261120224615 |
    |  1234567890 |   0.3163280927728192 |
    | 12345678901 |   0.7481621585303565 |
    +-------------+----------------------+
    5 rows in set (0.00 sec)
mysql> set @random:= rand();
Query OK, 0 rows affected (0.00 sec)

mysql> select @random;
+--------------------+
| @random            |
+--------------------+
| 0.7918265450669699 |
+--------------------+
1 row in set (0.00 sec)

mysql> select id,@random:=@random+1 from test_big;
+-------------+--------------------+
| id          | @random:=@random+1 |
+-------------+--------------------+
|          10 |   1.79182654506697 |
|          11 | 2.7918265450669697 |
|   123456789 | 3.7918265450669697 |
|  1234567890 |   4.79182654506697 |
| 12345678901 |   5.79182654506697 |
+-------------+--------------------+
5 rows in set (0.00 sec)
set @random:=floor(1 + RAND() * (1000 - 1));
MySQL - Selecting the number of rows in date range

MySQL - Selecting the number of rows in date range


By : sr tls
Date : March 29 2020, 07:55 AM
will be helpful for those in need Not sure you need the COALESCE part since you are LEFT JOINing, if you count on a field from the left joined table that may do the trick (since it won't count NULLs):
code :
SELECT 
   x.ts AS timestamp,
   COUNT(wp_paypal_logs.created) AS cnt
FROM (
    SELECT 
       DATE_FORMAT(DATE_ADD('2012-12-25', INTERVAL n.id - 1 DAY), '%Y-%m-%d') AS ts
    FROM numbers n
    WHERE DATE_ADD('2012-12-25', INTERVAL n.id - 1 DAY) <= '2012-12-31'
) x
LEFT JOIN wp_paypal_logs 
   ON STR_TO_DATE(wp_paypal_logs.created, '%Y-%m-%d') = x.ts
GROUP BY x.ts
Count number of rows that are at the minimum of a group MySQL

Count number of rows that are at the minimum of a group MySQL


By : user3774656
Date : March 29 2020, 07:55 AM
To fix the issue you can do I have a table that contains all the distinct names from another table, and then a column that holds the minimum value that the name received. For example, the table looks like this: , One way to do it is:
code :
SELECT m.Name,
       min_value,
       COUNT(CASE WHEN m.value = min_value THEN 1 END) As times_at_min
FROM mytable AS m
INNER JOIN (
   SELECT Name, 
          MIN(value) AS min_value       
   FROM mytable
   GROUP BY Name ) AS g
ON m.Name = g.Name
GROUP BY Name   
Selecting data based on number of occurences using Python / Pandas

Selecting data based on number of occurences using Python / Pandas


By : 0programmer
Date : March 29 2020, 07:55 AM
To fix this issue IIUC then you want to filter:
code :
df.groupby('Facility Type').filter(lambda x: len(x) > 50)
In [9]:
df = pd.DataFrame({'type':list('aabcddddee'), 'value':np.random.randn(10)})
df

Out[9]:
  type     value
0    a -0.160041
1    a -0.042310
2    b  0.530609
3    c  1.238046
4    d -0.754779
5    d -0.197309
6    d  1.704829
7    d -0.706467
8    e -1.039818
9    e  0.511638

In [10]:
df.groupby('type').filter(lambda x: len(x) > 1)

Out[10]:
  type     value
0    a -0.160041
1    a -0.042310
4    d -0.754779
5    d -0.197309
6    d  1.704829
7    d -0.706467
8    e -1.039818
9    e  0.511638
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