In this practice, I'd like to extarct the domain name from the TLD (Top Level Domain) given the following tables.
Table name: dns
+---------------------------+
| dnsdomain |
+---------------------------+
| ns2.hosting.indo.net.id. |
| ns1.onepanel.indo.net.id. |
| ns-1591.awsdns-06.co.uk. |
| mail189.atl21.rsgsv.net. |
| gli.websitewelcome.com. |
| ns2.metrolink.pl. |
| ns1.metrolink.pl. |
| ns-1591.awsdns-06.co.uk. |
| NS3.METRORED.HN. |
| NS.METRORED.HN. |
| ns2.hosting.indo.net.id. |
| ns1.onepanel.indo.net.id. |
| www.csis.ul.ie. |
+---------------------------+
and
Table name: tld
+----------+
| tld |
+----------+
| .net.id. |
| .co.uk. |
| .net. |
| .com. |
| .pl. |
| .uk. |
| .hn. |
| .id. |
| .ie. |
+----------+
I'd like to print out the dnstomain with its related tld. I perform the following mysql query:
select test.dnsdomain , tld.tld from test join tld where locate(tld.tld, test.dnsdomain, length(test.dnsdomain) - length (tld.tld) )!= 0;
and get the below table:
+---------------------------+----------+
| dnsdomain | tld |
+---------------------------+----------+
| ns2.hosting.indo.net.id. | .net.id. |
| ns1.onepanel.indo.net.id. | .net.id. |
| ns-1591.awsdns-06.co.uk. | .co.uk. |
| mail189.atl21.rsgsv.net. | .net. |
| gli.websitewelcome.com. | .com. |
| ns2.metrolink.pl. | .pl. |
| ns1.metrolink.pl. | .pl. |
| ns-1591.awsdns-06.co.uk. | .uk. |
| NS3.METRORED.HN. | .hn. |
| NS.METRORED.HN. | .hn. |
| ns2.hosting.indo.net.id. | .id. |
| ns1.onepanel.indo.net.id. | .id. |
| www.csis.ul.ie. | .ie. |
+---------------------------+----------+
The problem with my query is that for every single record in table 'test' it does not check all the tld from table 'tld' that's why I see something like:
| ns-1591.awsdns-06.co.uk. | .uk. |
where as the expected result would be like:
| ns-1591.awsdns-06.co.uk. | .co.uk. |
What I am doing wrong?
Try Group By function. This statement works in mysql :
select test.dnsdomain , tld.tld ,
max(length(tld.tld)) as x
from test
join tld
where locate(tld.tld, test.dnsdomain, length(test.dnsdomain) - length (tld.tld) )!= 0;
group by test.tnsdomain
OR
select test.dnsdomain , max(tld.tld) as tld
from test
join tld
where locate(tld.tld, test.dnsdomain, length(test.dnsdomain) - length (tld.tld) )!= 0;
group by test.tnsdomain
You're not doing anything wrong. That dnsname 'blah.co.uk.' matches both '.co.uk.' and '.uk.'. Both rows are being returned.
Sounds like you want to filter out all but the "longest" matching tld.
NOTE: I'd prefer to use the RIGHT() function to extract the rightmost portion from dnsdomain. (That's just easier for me to understand, but it should be equivalent to the expression you are using.)
Reference: RIGHT() https://dev.mysql.com/doc/refman/5.5/en/string-functions.html#function_right
One option to filter out the shorter matches is to use a correlated subquery to determine the maximum length of all of the tld that match, and only return the tld that has that length.
For example:
SELECT test.dnsdomain
, tld.tld
FROM test
JOIN tld
ON tld.tld = RIGHT(test.tndsdomain,CHAR_LENGTH(tld.tld))
WHERE CHAR_LENGTH(tld.tld) =
( SELECT MAX(CHAR_LENGTH(m.tld))
FROM tld m
WHERE m.tld = RIGHT(test.tndsdomain,CHAR_LENGTH(m.tld))
)
You could get an equivalent result using a JOIN operation to an inline view, it does basically the same thing:
SELECT test.dnsdomain
, tld.tld
FROM test
JOIN tld
ON tld.tld = RIGHT(test.tndsdomain,CHAR_LENGTH(tld.tld))
JOIN ( SELECT n.dnsdomain
, MAX(CHAR_LENGTH(m.tld)) AS tld_len
FROM test n
JOIN tld m
ON m.tld = RIGHT(n.tndsdomain,CHAR_LENGTH(m.tld))
GROUP BY n.dnsdomain
) o
ON o.dnsdomain = test.dnsdomain
AND o.tld_len = CHAR_LENGTH(tld.tld)
Also, it's better practice to use CHAR_LENGTH() function than LENGTH() function. The LENGTH() function returns a number of bytes, which is the same as the number of characters, for single byte character sets (like latin1), but with multibyte charactersets, the number of characters can be less than the number of bytes.)
Related
In the example below, I'm trying to create a query that returns the content of NAME if this contains both 'ammonium nitrate' and 'urea'. The thing is, they are in separate rows and I haven't found how to check for both. I've tried using the clauses IN, AND, and UNION, but to no avail.
The query should return only 'Gro-Fast', as it is the only NAME that contains both.
+-------+------------------+-------------+---------+
| FCODE | CNAME | NAME | CONTACT |
+-------+------------------+-------------+---------+
| 28994 | ammonium nitrate | Gro-Fast | 556698 |
| 28994 | urea | Gro-Fast | 556698 |
| 29462 | ammonium nitrate | BetterRoots | 342554 |
| 34588 | ammonium nitrate | Flourisher | 342554 |
| 83732 | urea | GreenAgain | 354211 |
+-------+------------------+-------------+---------+
TIA!
You can group by name and set the conditions in the HAVING clause:
select name
from tablename
where cname in ('ammonium nitrate', 'urea')
group by name
having count(distinct cname) = 2
If you want the column cnameto contain only 'ammonium nitrate' and 'urea':
select name
from tablename
group by name
having
sum(cname not in ('ammonium nitrate', 'urea')) = 0
and
count(distinct cname) = 2
See the demo.
Results:
> | name |
> | :------- |
> | Gro-Fast |
Edit, for your query:
select name
from CONTENTS natural join FERTILIZERS
where cname in ('ammonium nitrate', 'urea')
group by name
having count(distinct cname) = 2
I have mysql with a user table with answers from a poll saved as a bitwise. How do I find the user with most or least common answers with the reference bitwise?
+------+---------+--+
| User | Answers | |
+------+---------+--+
| A | 1 | |
| B | 5 | |
| C | 10 | |
+------+---------+--+
Assuming by 'reference bitwise' you mean that you have another value that is a bitmask that you are trying to match against the Answers column, something like this should do it for you. In this case, I'm using '4' as the reference bitmask and myTable as the name of your table..
SELECT User, BIT_COUNT(Answers & 4) AS MatchedBits FROM myTable ORDER BY MatchedBits DESC
This returns:
+------+-------------+
| User | MatchedBits |
+------+-------------+
| B | 1 |
| A | 0 |
| C | 0 |
+------+-------------+
You can also add a LIMIT 1 clause to get just the top result, but of course that won't tell you if there is more than one top result with the same number of bits matched.
I want to select value from table sorted by a certain order.
I have a table called test that looks like this:
| date | code | value |
+----------+-----------+----------+
| 20050104 | 000005.SZ | -6359.19 |
| 20050104 | 600601.SH | -7876.34 |
| 20050104 | 600602.SH | -25693.3 |
| 20050104 | 600651.SH | NULL |
| 20050104 | 600652.SH | -15309.9 |
...
| 20050105 | 000005.SZ | -4276.28 |
| 20050105 | 600601.SH | -3214.56 |
...
| 20170405 | 000005.SZ | 23978.13 |
| 20170405 | 600601.SH | 32212.54 |
Right now I want to select only one date, say date = 20050104, and then sort the data by a certain order (the order that each stock was listed in the stock market).
I have another table called stock_code which stores the correct order:
+---------+-----------+
| code_id | code |
+---------+-----------+
| 1 | 000002.SZ |
| 2 | 000004.SZ |
| 3 | 600656.SH |
| 4 | 600651.SH |
| 5 | 600652.SH |
| 6 | 600653.SH |
| 7 | 600654.SH |
| 8 | 600602.SH |
| 9 | 600601.SH |
| 10 | 000005.SZ |
...
I want to sorted the selected data by stock_code(code_id), but I don't want to use join because it takes too much time. Any thoughts?
I tried to use field but it gives me an error, please tell me how to correct it or give me an even better idea.
select * from test
where date = 20050104 and code in (select code from stock_code order by code)
order by field(code, (select code from stock_code order by code));
Error Code: 1242. Subquery returns more than 1 row
You told us that you don't want to join because it takes too much time, but the following join query is probably the best option here:
SELECT t.*
FROM test t
INNER JOIN stock_code sc
ON t.code = sc.code
WHERE t.date = '20050104'
ORDER BY sc.code_id
If this really runs slowly, then you should check to make sure you have indices setup on the appropriate columns. In this case, indices on the code columns from both tables as well as an index on test.date should be very helpful.
ALTER TABLE test ADD INDEX code_idx (code)
ALTER TABLE test ADD INDEX date_idx (date)
ALTER TABLE code ADD INDEX code_idx (code)
As I said in the title, or maybe my question is a little bit confusing. Here it is....
So, I want to combine 2 tables using INNER JOIN (ofcourse) with some difference.
This is my tables
Table 1, PK = steam_id
SELECT * FROM nmrihstats ORDER BY points DESC LIMIT 4;
+---------------------+----------------+--------+-------+--------+
| steam_id | name | points | kills | deaths |
+---------------------+----------------+--------+-------+--------+
| STEAM_0:1:88467338 | Alan14 | 50974 | 5438 | 12 |
| STEAM_0:0:95189481 | ? BlacKEaTeR ? | 35085 | 24047 | 316 |
| STEAM_0:1:79891668 | Lowell | 34410 | 44076 | 993 |
| STEAM_0:1:170948255 | Rain | 29780 | 30167 | 278 |
+---------------------+----------------+--------+-------+--------+
4 rows in set (0.01 sec)
Table 2, PK = authid
SELECT * FROM store_players ORDER BY credits DESC LIMIT 4;
+-----+-------------+---------------+---------+--------------+-------------------+
| id | authid | name | credits | date_of_join | date_of_last_join |
+-----+-------------+---------------+---------+--------------+-------------------+
| 309 | 1:88467338 | Alan14 | 15543 | 1475580801 | 1482260232 |
| 368 | 1:79891668 | Lowell | 10855 | 1475603908 | 1482253619 |
| 256 | 1:128211488 | Fuck[U]seLF | 10422 | 1475570061 | 1482316480 |
| 428 | 1:74910707 | Mightybastard | 7137 | 1475672897 | 1482209608 |
+-----+-------------+---------------+---------+--------------+-------------------+
4 rows in set (0.00 sec)
Now, how can I use INNER JOIN without doing like removing "STEAM_0:" or adding it. Also with explanation, please
You can join witn like operator, e.g.:
SELECT n.*, sp.*
FROM nmrihstats n JOIN store_players sp ON n.steam_id LIKE CONCAT('%', sp.authid);
Here's the SQL Fiddle.
Another approach would be to use String functions of MySQL to extract out relevant part from steam_id but I believe that's not what you want:
SELECT SUBSTR(steam_id, LOCATE('STEAM_0:', steam_id) + CHAR_LENGTH('STEAM_0:'))
FROM nmrihstats;
it is not possible, you need to remove "STEAM_0:", matching with WHERE, using substring for remove STEAM_0: from column equals to column in other table, or a new field into the T1 without "STEAM_0:", that 2 columns match for INNER JOIN
I'm trying to identify if a row has the value '1' anywhere in it (AKA any column). Is there an easy way to do this without searching every column with fetchrow_array? I've included a small table I've been working with as an example.
mysql> select * from Case_Tracking;
+--------------------+---------+---------+----------+---------+----------+---------------+
| accession_number | cyp2d6 | cyp2c19 | factorII | factorV | apoe | vkorc1_cyp2c9 |
+--------------------+---------+---------+----------+---------+----------+---------------+
| AIB14-1116-0000453 | Luminex | Luminex | Hologic | 1 | ABI 7500 | Genmark |
| AIB14-1123-0000074 | NULL | Luminex | Hologic | Hologic | ABI 7500 | Genmark |
+--------------------+---------+---------+----------+---------+----------+---------------+
It would be better to search every column using SQL (WHERE accession_number = '1' OR cyp2d6 = '1' OR ...) since you'd only need to fetch matching results.