I have a table in a MySQL database. I want to display the item number (not the primary key) and then a row number.
item_num, row_number
1, 1
12, 2
1234, 3
15, 4
29, 5
Here is my query:
select item_num, row_number() over(partition by item_num) from items;
My output is this:
item_num, row_number
1, 1
12, 1
1234, 1
15, 1
29, 1
How can I fix this issue and show the correct row number for each item?
Answer
The following query should create the behaviour you want:
SELECT item_num, ROW_NUMBER() OVER() FROM items;
Explanation
The ROW_NUMBER() formula sequentially numbers the rows of each partition which is passed into it. It begins again at 1 for each partition, independently. Therefore, attempting to partition the database by item_num before using ROW_NUMBER() will result in each unique item_num being assigned a row number of 1.
Instead, use a blank OVER() clause. There's no need to partition the database or order it in any specific way, since you simply want to apply ROW_NUMBER() based on the order already present in the database.
Related
I want to get data from table where Id should be as given below in the query but instead of or I would apply and operator so lets say ID IN (5 AND 4 AND 3)
SELECT * FROM table WHERE id IN (5,4,3,1,6)
Is it possible to get data like this.
This is the sample query
SELECT PM.ContentID, PM.Author, PM.Title, PM.Journal, PM.Year, PM.Category, PM.StudyLocation, PM.FileURL from PublishedContentMaster PM join TopicContentMapping T ON T.ContentID=PM.ContentID where PM.ContentID='100' AND T.TopicID IN (16,7)
So I want which is present in both 16 and 17 that is why I need and operator not or.
I suspect that you want an aggregation query and a having clause. It would typically look something like this:
select x
from t
where id in (5, 4, 3, 1, 6)
group by x
having count(*) = 5;
In this case, x would be the column where you want five rows with the five values.
I am stuck with the following issue. I have 1 table that looks like this:
field_number.. Value
````````````````````````````````
1 ......................... 1
2 ..........................1
3 ......................... 2
4 ..........................2
etc.
I want to group different fieldnumbers and have an average for the value column. So the output should be:
field_number................Value
name(1,2)...................... 1.............. ((1+1)/2)
name(3,4)...................... 2.............. ((2+2)/2)
I have checked previous questions but cannot find any question that covers this issue (I might search on the wrong keywords though). So if this has already been covered my appologies, but any help or a point to a previous answer would be appreciated.
** =============UPDATE============= **
I went through your suggestions but did not get it right. So I am trying to be more specific. I almost have the result I want apart from the fact I want to have a fixed value in one of my columns. I have the following query:
Select
Avg(wp_rg_lead_detail.value),
wp_rg_lead_detail.field_number,
From
wp_rg_lead_detail
Where
wp_rg_lead_detail.field_number In (15, 17, 24) A
UNION
Select
Avg(wp_rg_lead_detail.value),
wp_rg_lead_detail.field_number,
From
wp_rg_lead_detail
Where
wp_rg_lead_detail.field_number In (16, 108, 18)
etc.
This gives me a table with two columns
wp_rg_lead_detail.value................field_number
4.3 (average)..............................15 (first value of av calculation)
What I want is to change the field number (15 in this case) in a fixed value (text). What and how should I add this to the query?
SELECT avg(value) FROM table WHERE field_number in (1,2)
SELECT avg(value) FROM table WHERE field_number in (3,4)
If your table is really this simple, you can also get away with:
select distinct
Value,
count(Value) as '#'
from table_name
group by Value
If you acctually want to group by a range, than you can put the logic of the range in your grouping clause (see this fiddle)
select distinct
avg(Value) as average,
floor(Value),
count(Value) as '#'
from table_name
group by floor(Value)
In the fiddle I used grouping on whole integers, but you can make that as complex as you like (see, for instance, this example)
If you are actually also interested in your corresponding fields, use group_concat() like so
select
Value,
group_concat(
distinct field_number
order by Value
) as fields
from table_name tn1
group by Value
order by Value
output:
Value | fields
---------------------------------
1 | 1,2
2 | 3,4
See this fiddle implemented from this blog post
For a generalized answer.
SELECT CONCAT('name','(',GROUP_CONCAT(field_number),')') AS field_number,
AVG(Value) as Value
FROM table_name
group by table_name.`Value`
Hope this helps.
In my MySQL table I have field called sequence where I have values like
1 , 2, 3, 5, 6, 7, 8, 10 some of the sequence number are skiped due to deleted records. How do I find out next available number from given number. let's say if I need next number from 3 , how do I get number 5 as my next number in sequence not the 4.
To find out the next ID after 3 that appears in your table, you should do
SELECT id FROM thetable WHERE id>3 ORDER BY id ASC LIMIT 1
This just considers IDs that are greater than 3, in ascending order, and then takes the first one on that list. If it returns you one result, then that's the next one used in the table; if it doesn't return a result at all, then the ID you gave it was already the highest one in the table (or, strictly speaking, at least as high as the highest one in the table).
If you want a general expression that works to get the next available number, then you can use an aggregation query:
select coalesce(max(id), maxid + 1) as NextAvailableId
from table t cross join
(select max(id) as maxid from table t) x
where id > 3;
Or, if you don't like the cross join, you can use conditional aggregation:
select coalesce(max(case when id > 3 then id end), max(id)) as NextAvailableId
from table t;
I have a contents table and the entires in it are as shown in the attached figure
There are more than 100,000 entries. I want to fetch the data where the update_date for commit=0 is greater than update_date for commit=1. I also need the corresponding row for commit=1.
I tried a few things, but takes a long time to retrieve the results. What is the best SQL query I can use. I am using MySQL database.
EDIT
I have now updated the table. There is an attribute called content_id which binds the rows together.
A query like this gives me half of what I want
select a.* from contents a, contents b where
a.content_id=b.content_id and
a.update_date > b.update_date and
a.committed=0 and b.committed=1
I also want the corresponding entries from committed=1, but they should be appended at the bottom as rows and not vertically concatenated as columns.
For example, I cannot use
select * from contents a, contents b where
a.content_id=b.content_id and
a.update_date > b.update_date and
a.committed=0 and b.committed=1
because the results from 'b' are appended vertically. Also, is there a better way to write this query. This works really slow if there are many entries in the database.
I am assuming that in the above example, you only need id=2 as for content id = 1, the update_date for commit=0 is greater than update_date for commit=1 and in that case you need data for commited = 1.
I an using Oracle, so you need to find a suitable replacement for row_number() funtion in mysql.
The logic would be
Create a view on the existing table to use rownumber so it will give rownumber like below order by time desc (see if you use a nested query to do it)
ID, CONTENT_ID, COMMITED, UPDATE_DATE, ROWN
2 1 1 06-SEP-15 00:00:56 1
1 1 0 07-SEP-15 00:00:56 2
3 2 0 03-SEP-15 00:00:56 1
4 2 1 04-SEP-15 00:00:56 2
Now select only rows where where rown=1 and commited=1
This is the query in oracle. The second with query c2 will be your view.
Oracle query
with c1 (id, content_id,commited,update_date) as
(
select 1,1,0,sysdate from dual union
select 2,1,1,sysdate-1 from dual union
select 3,2,0,sysdate-4 from dual union
select 4,2,1,sysdate-3 from dual
),
c2 as
(select c1.*,row_number() over(partition by content_id order by update_date) as rown from c1)
select id,content_id,commited,update_date from c2
where rown=1 and commited=1
ID, CONTENT_ID, COMMITED, UPDATE_DATE, ROWN
Output
ID, CONTENT_ID, COMMITED, UPDATE_DATE
2 1 1 06-SEP-15 00:06:17
I want to count from the row with the least value to the row with a specific value.
For example,
Name / Point
--------------------
Pikachu / 7
Voltorb / 1
Abra / 4
Sunflora / 3
Squirtle / 8
Snorlax / 12
I want to count to the 7, so I get the returned result of '4' (counting the rows with values 1, 3, 4, 7)
I know I should use count() or mysql_num_rows() but I can't think of the specifics.
Thanks.
I think you want this :
select count(*) from mytable where Point<=7;
Count(*) counts all rows in a set.
If you're working with MySQL, then you could ORDER BY Point:
SELECT count(*) FROM table WHERE Point < 7 ORDER BY Point ASC
If you want to know all about ORDER BY, check out the w3schools page: http://www.w3schools.com/sql/sql_orderby.asp
Just in case you want to only count the rows based on the Point values:
SELECT count(*) FROM table WHERE Point < 7 GROUP BY Point
This may help you to get rows falling between range of values :
select count(*) from table where Point >= least_value and Point<= max_value