I have a table of orders. For each order, we allow the user to enter their (non-unique) order number. This can we whatever they want.
I have these orders displayed in an HTML table, with the ability to sort the orders by various fields, such as order number.
One of our clients noticed an issue with the sorting. Since the order numbers are stored as VARCHAR, they are sorted lexicographically. Problem is, not all order numbers are numerc, some are words, and others are alphanumeric.
So, for example, I can have order numbers like so:
42
Order8
MyOrder
9
Order63
When sorted using ORDER BY orderNumber, I get:
42
9
MyOrder
Order63
Order8
DEMO: http://sqlfiddle.com/#!2/7973e/1
This is not what I want. I want them to be sorted like so:
9
42
MyOrder
Order8
Order63
I want them to be lexicographical for the strings, but numeric for the numbers. I thought of something that might work:
ORDER BY IFNULL(NULLIF(CAST(orderNumber AS SIGNED), 0), orderNumber)
DEMO: http://sqlfiddle.com/#!2/7973e/2
But alas, I still get the same results (as the numbers are then re-cast back to strings). How can I sort these values in the way that I want? If only there was some way to "convert" the strings into a sort of numerical value.
You could try padding the order number with zeros when you see a numeric value. See this, for example:
http://sqlfiddle.com/#!2/7973e/21
SELECT
CASE
WHEN CAST(orderNumber AS SIGNED) != 0 THEN LPAD(orderNumber, 10, '0')
ELSE orderNumber
END as padded,
orders.*
FROM orders
ORDER BY
padded
Results in :
| PADDED | ORDERID | ORDERNUMBER |
--------------------------------------
| 0000000009 | 4 | 9 |
| 0000000042 | 1 | 42 |
| MyOrder | 3 | MyOrder |
| Order63 | 5 | Order63 |
| Order8 | 2 | Order8 |
Full disclosure: I'm the author of SQL Fiddle.
You can get close to what you want with the following:
ORDER BY CASE WHEN CONVERT(OrderNumber, SIGNED INTEGER)= 0
THEN 1e50
ELSE CONVERT(OrderNumber, SIGNED INTEGER)
END ASC, OrderNumber ASC
However, it would need more work if you need to sort a mixed (text/number) order number by its last digits (e.g. Order63, Order8).
Related
I have a MariaDB table with an archive of past lottery results, imagine EuroMillions or Powerball lotteries.
For example on EuroMillions numbers go from 1 to 50 and then the extra balls from 1 to 12, each result is 5 numbers form the main pool and 2 from the extra pool. So my historic results table could look like this:
Lottery Results table
(other columns like id, date, draw number, etc) | main_numbers | extra_numbers | (timestamp columns)
... | 1,2,3,4,5 | 1,2 | ...
... | 3,12,34,35,45 | 5,11 | ...
... | 4,15,34,39,45 | 10,11 | ...
... | 7,11,25,28,44 | 10,12 | ...
(you get the idea, I have thousands of records...)
So I could select main_numbers and get result "3,12,34,35,45" for that second example row. And for the extra_numbers I would get "5,11".
What I want is to given a set of numbers for main and extra to see if they match any of my results, finding any number of numbers (numbered lottery balls).
So for example if I SELECT to find main_numbers "5,9,22,34,45" with extra_numbers "2,11" I would get (from my extracted example) two records:
... | 3,12,34,35,45 | 5,11 | ...
... | 4,15,34,39,45 | 10,11 | ...
Matching two main numbers and one extra number, in this case finding lottery prizes in the results table. Makes sense?
I'm using MariaDB and I'm a bit lost on how to proceed, I tried WHERE IN, FIELD_IN_SET, etc.
Is there a way to perform a SELECT to find results in only one statement or do I have to pick all records and then iterate elsewhere, php for example?
My aim would be to have it in one statement, so I could just send the numbers and get the matching records... Possible?
I hope this makes sense.
Many thanks for your answers.
Consider the following.
For simplicity, let's say that a lottery comprises 3 main balls, and two bonus balls:
DROP TABLE IF EXISTS lottery_results;
CREATE TABLE lottery_results
(draw_id INT NOT NULL
,ball_no INT NOT NULL
,ball_val INT NOT NULL
,PRIMARY KEY(draw_id,ball_no)
);
INSERT INTO lottery_results VALUES
(1,1,22),
(1,2,35),
(1,3,62),
(1,4,27),
(1,5,17),
(2,1,18),
(2,2,33),
(2,3,49),
(2,4, 4),
(2,5,35);
And we want to find all results where 34, 35, or 36 were drawn as a main number...
SELECT draw_id
FROM lottery_results
WHERE ball_no <=3
AND ball_val IN(34,35,36);
+---------+
| draw_id |
+---------+
| 1 |
+---------+
Thanks Strawberry,
I found a solution if I have all numbers in distinct columns, but could I find if they are in the same column in CSV?
So if I put my CSV in distinct columns for numbers (n_1...n_5) and extra numbers for the stars in (s_1, s_2) I can seek matched in those multiple columns.
This is using multiple columns:
To find matches numbers 1,2,3,4,5 with stars 1,2...
In EuroMillions you get a prize with 2 or more numbers and any star (one or two).
SELECT
main_numbers, extra_numbers,
((n_1 IN (1,2,3,4,5)) +
(n_2 IN (1,2,3,4,5)) +
(n_3 IN (1,2,3,4,5)) +
(n_4 IN (1,2,3,4,5)) +
(n_5 IN (1,2,3,4,5))) AS matched_numbers,
((s_1 IN (1,2)) +
(s_2 IN (1,2))) AS matched_stars,
created_at
FROM `lottery_results_archive`
HAVING matched_numbers >= 3 OR matched_numbers = 2 AND matched_stars > 0
ORDER BY matched_numbers DESC, matched_stars DESC, created_at DESC
Makes sense?
Thanks.
I have a table users but i have shown only 2 columns I want to sum all the characters of name column.
+----+-------+
| id | name |
+----+-------+
| 0 | user |
| 1 | admin |
| 3 | edit |
+----+-------+
for example ascii sum of user will be
sum(user)=117+115+101+114=447
i have tired this
SELECT ASCII(Substr(name, 1,1)) + ASCII(Substr(name, 2, 1)) FROM user
but it only sums 2.
You are going to have to fetch one character at a time to do the sum. One method is to write a function with a while loop. You can do this with a SELECT, if you know the longest string:
SELECT name, SUM(ASCII(SUBSTR(name, n, 1)))
FROM user u JOIN
(SELECT 1 as n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL
SELECT 4 UNION ALL SELECT 5 -- sufficient for your examples
) n
ON LENGTH(name) <= n.n
GROUP BY name;
If your goal is to turn the string as something that can be easily compared or a fixed length, then you might consider the encryption functions in MySQL. Adding up the ASCII values is not a particularly good hash function (because strings with the same characters in different orders produce the same value). At the very least, multiplying each ASCII value by the position is a bit better.
I know basic MySQL querying, but I have no idea how to achieve an accurate and relevant search query.
My table look like this:
id | kanji
-------------
1 | 一子
2 | 一人子
3 | 一私人
4 | 一時
5 | 一時逃れ
I already have this query:
SELECT * FROM `definition` WHERE `kanji` LIKE '%一%'
The problem is that I want to order the results from the learnt characters, 一 being a required character for the results of this query.
Say, a user knows those characters: 人,子,時
Then, I want the results to be ordered that way:
id | kanji
-------------
2 | 一人子
1 | 一子
4 | 一時
3 | 一私人
5 | 一時逃れ
The result which matches the most learnt characters should be first. If possible, I'd like to show results that contain only learnt characters first, then a mix of learnt and unknown characters.
How do I do that?
Per your preference, ordering by number of unmatched characters (increasing), and then number of matched character (decreasing).
SELECT *,
(kanji LIKE '%人%')
+ (kanji LIKE '%子%')
+ (kanji LIKE '%時%') score
FROM kanji
ORDER BY CHAR_LENGTH(kanji) - score, score DESC
Or, the relational way to do it is to normalize. Create the table like this:
kanji_characters
kanji_id | index | character
----------------------------
1 | 0 | 一
1 | 1 | 子
2 | 0 | 一
2 | 1 | 人
2 | 2 | 子
...
Then
SELECT kanji_id,
COUNT(*) length,
SUM(CASE WHEN character IN ('人','子','時') THEN 1 END) score
FROM kanji_characters
WHERE index <> 0
AND kanji_id IN (SELECT kanji_id FROM kanji_characters WHERE index = 0 AND character = '一')
GROUP BY kanji_id
ORDER BY length - score, score DESC
Though you didn't specify what should be done in the case of duplicate characters. The two solutions above handle that differently.
Just a thought, but a text index may help, you can get a score back like this:
SELECT match(kanji) against ('your search' in natural language mode) as rank
FROM `definition` WHERE match(`kanji`) against ('your search' in natural language mode)
order by rank, length(kanji)
The trick is to index these terms (or words?) the right way. I think the general trick is to encapsulate each word with double quotes and make a space between each. This way the tokenizer will populate the index the way you want. Of course you would need to add/remove the quotes on the way in/out respectively.
Hope this doesn't bog you down.
I have a table (pretty big one) with lots of columns, two of them being "post" and "user".
For a given "post", I want to know which "user" posted the most.
I was first thinking about getting all the entries WHERE (post='wanted_post') and then throw a PHP hack to find which "user" value I get the most, but given the large size of my table, and my poor knowledge of MySQL subtle calls, I am looking for a pure-MySQL way to get this value (the "user" id that posted the most on a given "post", basically).
Is it possible ? Or should I fall back on the hybrid SQL-PHP solution ?
Thanks,
Cystack
It sounds like this is what you want... am I missing something?
SELECT user
FROM myTable
WHERE post='wanted_post'
GROUP BY user
ORDER BY COUNT(*) DESC
LIMIT 1;
EDIT: Explanation of what this query does:
Hopefully the first three lines make sense to anyone familiar with SQL. It's the last three lines that do the fun stuff.
GROUP BY user -- This collapses rows with identical values in the user column. If this was the last line in the query, we might expect output something like this:
+-------+
| user |
+-------+
| bob |
| alice |
| joe |
ORDER BY COUNT(*) DESC -- COUNT(*) is an aggregate function, that works along with the previous GROUP BY clause. It tallies all of the rows that are "collapsed" by the GROUP BY for each user. It might be easier to understand what it's doing with a slightly modified statement, and it's potential output:
SELECT user,COUNT(*)
FROM myTable
WHERE post='wanted_post'
GROUP BY user;
+-------+-------+
| user | count |
+-------+-------+
| bob | 3 |
| alice | 1 |
| joe | 8 |
This is showing the number of posts per user.
However, it's not strictly necessary to actually output the value of an aggregate function in this case--we can just use it for the ordering, and never actually output the data. (Of course if you want to know how many posts your top-poster posted, maybe you do want to include it in your output, as well.)
The DESC keyword tells the database to sort in descending order, rather than the default of ascending order.
Naturally, the sorted output would look something like this (assuming we leave the COUNT(*) in the SELECT list):
+-------+-------+
| user | count |
+-------+-------+
| joe | 8 |
| bob | 3 |
| alice | 1 |
LIMIT 1 -- This is probably the easiest to understand, as it just limits how many rows are returned. Since we're sorting the list from most-posts to fewest-posts, and we only want the top poster, we just need the first result. If you wanted the top 3 posters, you might instead use LIMIT 3.
Let's suppose that I have these tables:
[ properties ]
id (INT, PK)
name (VARCHAR)
[ properties_prices ]
id (INT, PK)
property_id (INT, FK)
date_begin (DATE)
date_end (DATE)
price_per_day (DECIMAL)
price_per_week (DECIMAL)
price_per_month (DECIMAL)
And my visitor runs a search like: List the first 10 (pagination) properties where the price per day (price_per_day field) is between 10 and 100 on the period for 1st may until 31 december
I know thats a huge query, and I need to paginate the results, so I must do all the calculation and login in only one query... that's why i'm here! :)
Questions about the problem
If there are gaps, would that be an acceptable property?
There're no gaps. All the possible dates are in the database.
If the price is between 10 and 100 in some sup-periods, but not in others, do you want to get that property?
In the perfect world, no... We'll need to calculate the "sum" of that type of price in that period considering all the variations/periods.
Also, what are the "first 10"? How are they ordered? Lowest price first? But there could be more than one price.
This is just an example of pagination with 10 results per page... Can be ordered by the FULLTEXT search that I'll add with keywords and these things... As I said, it's a pretty big query.
This is similar to the answer given by #mdma, but I use a condition in the join clause for the price range, instead of the HAVING trick.
SELECT p.id, MAX(p.name),
MIN(v.price_per_day) AS price_low,
MAX(v.price_per_day) AS price_high
FROM properties p
JOIN properties_prices v ON p.id = v.property_id
AND v.price_per_day BETWEEN 10 AND 100
AND v.date_begin < '2010-12-31' AND v.date_end > '2010-05-01'
GROUP BY p.id
ORDER BY ...
LIMIT 10;
I would also recommend creating a covering index:
CREATE INDEX prices_covering ON properties_prices
(property_id, price_per_day, date_begin, date_end);
This allows your query to run as optimally as possible, because it can read the values directly from the index. It won't have to read the rows of data from the table at all.
+----+-------------+-------+-------+-----------------+-----------------+---------+-----------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+-----------------+-----------------+---------+-----------+------+--------------------------+
| 1 | SIMPLE | p | index | PRIMARY | PRIMARY | 4 | NULL | 1 | |
| 1 | SIMPLE | v | ref | prices_covering | prices_covering | 4 | test.p.id | 6 | Using where; Using index |
+----+-------------+-------+-------+-----------------+-----------------+---------+-----------+------+--------------------------+
What you tell us is not precise enough. From your data structure and your question I assume:
the price of a property can change in that period, and there would be a properties_price entry for each sub-period
there should be no overlaps in the sub-periods, but the data structure does not guarantee that
there can be gaps in the sub-periods
But there are still questions:
If there are gaps, would that be an acceptable property?
If the price is between 10 and 100 in some sup-periods, but not in others, do you want to get that property?
Also, what are the "first 10"? How are they ordered? Lowest price first? But there could be more than one price.
Depending on the answers, there might be no single query doing the trick. But if you accept the gaps, that could return what you want:
SELECT *
FROM properties AS p
WHERE EXISTS -- property is available in the price range
(SELECT * FROM properties_prices AS pp1
WHERE p.id = pp1.property_id AND
pp1.price_per_day between 10 and 100 AND
(pp1.date_begin <= "2010-12-31" OR pp1.date_end >= "2010-05-01")) AND
NOT EXISTS -- property is in the price range in all sup-periods, but there might be gaps
(SELECT * FROM properties_prices AS pp2
WHERE p.id = pp2.property_id AND
pp2.price_per_day not between 10 and 100 AND
(pp2.date_begin <= "2010-12-31" OR pp2.date_end >= "2010-05-01"))
ORDER BY name --- ???
LIMIT 10
That query doesn't give you the prices or other details. That would need to go in an extra query. But perhaps my assumptions are all wrong anyway.
This can also be done as a GROUP BY, which I think will be quite efficient, and we get some aggregates as part of the package:
SELECT
prperty_id, MIN(price_per_day), MAX(price_per_day)
FROM
properties_prices
WHERE
date_begin <= "2010-12-31" AND date_end >= "2010-05-01"
GROUP BY
property_id
HAVING MIN(IF( (price_per_day BETWEEN 10 AND 100), 1, 0))=1
ORDER BY ...
LIMIT 10
(I don't have MySQL to hand so I haven't tested. I was unsure about the MIN(IF ...) but a mock-up using a CASE worked on SQLServer.)