I have two tables, one has single entries like this:
'rs47' 1027
The other has ranges:
'gene1' 1000 1500
These tables are huge, so I am trying to figure out the most efficient way to get all entries from table 1 where the entries are within any range in table 2.
I don't think that INTERSECT can be used like this. I know how to use SELECT to do this for a single entry:
SELECT name FROM 'table2' INDEXED BY 'start_end' WHERE 1027 BETWEEN start AND end
But I am not sure how to do that for every record in a table. Any ideas?
To check whether corresponding rows exist in the other table, you can use a correlated subquery:
SELECT *
FROM Table1
WHERE EXISTS (SELECT 1
FROM Table2
WHERE Table1.Value BETWEEN Table2.StartValue AND Table2.EndValue);
Related
I have a database that has two integer columns, and I'm trying to find a way to select the top 'x' amount of rows with the highest sums of these two columns. I'm trying to eliminate the need of creating a third column that stores the sum of the two, unless there's a way to to automatically update this column every time one of the other two are altered. I'm using SQLite by the way, as I know there are some slight differences here and there between SQL/SQLite syntax.
Any help is appreciated.
Something like
SELECT a, b
FROM yourtable
ORDER BY a + b DESC
LIMIT :x
should do it.
We have a table students with ID,NAME,SURNAME. We want have another table (created) students_2 with ID1,NAME1,SURNAME1.
Starting from table students, i want to fill data in the second table in the following way : I want to have in the second table combinations of names ( example : NAME,SURNAME1; NAME1,SURNAME1). Moreover, i want to generate combination of names.
How can I do that ? I tried something like :
INSERT INTO students_2 (ID1,NAME1,SURNAME1) SELECT ID,NAME,NAME from students;
But it's not correct cause I don't generate combinations, just inserting . A solution is appreciated, but mainly i need ideas.
You could write something like
INSERT INTO students2(NAME, VALUE) FROM
SELECT s1.name, s2.value from students1 s1 cross join students1 s2
This will do Cartesian product , and will get a NxN rows with combinations
I have a SQL database with 30 tables ordered by company names. They are 30 stocks. Each table has columns date, high, low, close and volume.
My question is: how do I select the first record of each table in SQL?
Is it
FROM TOP 1 * SELECT aaple_30min?
I tried
SELECT *
FROM bac_30min
LIMIT 1
but this gives me only for one table.
I have decided to write the query in R, where I will loop through the companies in question and use the paste function to make calls by replacing above "bac_30" with company names as strings.
I am examining a .sqlite file in FireFox's SQLite Manager and need to see if any data was not collected. An example is worth a thousand words:
ReadDate ReadValue
1361900350183.00 137
1361899753183.00 139
1361900053183.00 138
The are no primary keys and the table is NOT sorted by ReadDate or time. [Changing the input table is not an option!]
What I'd like to do is produce with simple SQL a table that looks like this:
ReadDate ReadValue TimeOffset
1361899753183.00 139
1361900053183.00 138 300000 // this is ReadDate(1) - ReadDate(0)
1361900350183.00 137 297000 // this is ReadDate(2) - ReadDate(1)
This would allow me to inspect the data and see if any data values were not captured (TimeOffset would be much greater than 300000). I could also write an additional query to get a COUNT of all TimeOffsets beyond a threshold.
I'm having trouble getting going on what I imagine is a simple exercise. I know how to do joins and sorts (order by), but here I need to compare one row to another. Do I need a cursor? And how to get the extra column? I have a gut feeling that if I just knew the vocabulary a little better, I'd be able to come up with the search terms and find the answer quickly.
Many thanks,
Dave
First, add an (empty) column to your table:
ALTER TABLE MyTable ADD COLUMN TimeOffset NUMERIC;
Then, the TimeOffset for each record is the difference between the ReadDate column of this record and of the record with the next smaller ReadDate, i.e, the record with the largest ReadDate that is still smaller than this one's:
UPDATE MyTable
SET TimeOffset = ReadDate - (SELECT MAX(ReadDate)
FROM MyTable AS t2
WHERE t2.ReadDate < MyTable.ReadDate);
I have two tables, one contains a list of items which is called watch_list with some important attributes and the other is just a list of prices which is called price_history. What I would like to do is group together 10 of the lowest prices into a single column with a group_concat operation and then create a row with item attributes from watch_list along with the 10 lowest prices for each item in watch_list. First I tried joins but then I realized that the operations where happening in the wrong order so there was no way I could get the desired result with a join operation. Then I tried the obvious thing and just queried the price_history for every row in the watch_list and just glued everything together in the host environment which worked but seemed very inefficient. Now I have the following query which looks like it should work but it's not giving me the results that I want. I would like to know what is wrong with the following statement:
select w.asin,w.title,
(select group_concat(lowest_used_price) from price_history as p
where p.asin=w.asin limit 10)
as lowest_used
from watch_list as w
Basically I want the limit operation to happen before group_concat does anything but I can't think of a sql statement that will do that.
Figured it out, as somebody once said "All problems in computer science can be solved by another level of indirection." and in this case an extra select subquery did the trick:
select w.asin,w.title,
(select group_concat(lowest_used_price)
from (select lowest_used_price from price_history as p
where p.asin=w.asin limit 10)) as lowest_used
from watch_list as w