I've stored a X, Y coordinate system in mysql where x-axis values are from A, B....AA, AB... and so forth, just like columns are named in Excel. Y-axis values are from 1 to 100.
I can't figure out how to select all x-axis values that are "lower" than i.e. 'AZ'. My query result should be A, B, C...AA, AB...AZ values, but mysql considers B to be greater than AA.
SELECT x_axis, y_axis
FROM coordinates
WHERE x_axis<'AZ'
ORDER BY length(substring_index(x_axis, ' ', 1)),
substring_index(x_axis, ' ', 1);
Hope my question makes sense.
Thanks
I managed to make the sorting correct, but I am stuck with the WHERE part and mysqls alphabetic sorting
Your query should be ordered by two values: length of x_axis and x_axis values.
SELECT x_axis, y_axis
FROM coordinates
WHERE LPAD(x_axis, 2, ' ') < LPAD('AZ', 2, ' ')
ORDER BY LENGTH(x_axis), x_axis;
You could try sample query here: https://onecompiler.com/mysql/3yupevx2v
String comparison in MySQL is case-sensitive, and it compares the ASCII values of the characters. Since 'Z' has a greater ASCII value than 'A', 'AZ' is considered greater than 'AA'.
To solve this issue, you can use the ORDER BY clause with a custom sorting order. You can use the FIELD() function to assign a custom order to your x_axis values, then use that value in the ORDER BY clause.
SELECT x_axis, y_axis FROM coordinates
WHERE FIELD(x_axis, 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','AA','AB','AC'... )<
FIELD('AZ')
ORDER BY FIELD(x_axis, 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','AA','AB','AC'...);
If you want the solution to be more reusable you can set a user-defined variable to store the order of each x_axis value, and then use that variable in the ORDER BY clause.
SET #i:=0;
SELECT x_axis, y_axis, #i:=#i+1 as sort_order FROM coordinates
WHERE x_axis<'AZ'
ORDER BY sort_order;
Related
How do I select a value range from a column where two values in it are separated by a dash, using MySQL?
Here's my example table named "example":
The user enters a low value (X) and a high value (Y).
For example X=2.5 and Y=7.2
I want to select all items where the left value is higher than X (in this case 2.5) and the right value is lower than Y (in this case 7.2). Using these X and Y values I should end up with the rows 2 and 5 as a result.
Sort of like this:
SELECT * FROM example WHERE MIN(value) > X AND MAX(value) < Y
How do I do this?
You can use LEFT and RIGHT functions to get X and Y out of your value field.
So I think you are looking for something like this:
SELECT * FROM example WHERE CAST(LEFT(value,3)AS DECIMAL(2,1)) > 2.5 and CAST(RIGHT(value,3)AS DECIMAL(2,1)) < 7.2
First you need to access your table in a fashion that only has one value per column. (Multiple values per column, like 3.5-7.5 happen to be a very common relational database design antipattern. They cripple both performance and clarity.)
This SQL subquery does the trick for pairs of values.
SELECT item_id, name,
0.0+SUBSTRING_INDEX(value, '-',1) first,
0.0+SUBSTRING_INDEX(value, '-', -1) last
FROM example;
The expression 0.0+something is a MySQL trick to coerce a value to be numeric.
Then use the subquery to apply your search criteria.
SELECT item_id, name, first, last
FROM ( SELECT item_id, name,
0.0+SUBSTRING_INDEX(value, '-',1) first,
0.0+SUBSTRING_INDEX(value, '-', -1) last
FROM example
) s
WHERE first > 2.5
AND last < 7.2;
Fiddle here.
In a comment you asked about the situation where you have more than two values in a single column separated by delimiters. See this. Split comma separated values in MySQL
Pro tip Don't put more than one number in a column in an RDBMS table. The next person to use the table will be muttering curses all day while trying to use that data.
Pro tip Use numeric data types, not VARCHAR(), for numbers.
So I know how to sort a mixed column of numbers, i.e.
A1, A2, A3
My question is if it had a mixed set of numbers i.e.
Name_01022017_number-001
How would I go about sorting by that second number set and not the first set? I'd rather sort by that number than the date. Thanks.
You can use something like this:
SELECT CAST('123abc' AS UNSIGNED) AS fieldname;
and ORDER BY fieldname
First, you need to use the substring function to get the number or string you want to sort with. I assume that you want to use 001 in this case
select * from table order by substring(column, start position, len)
Just asking if this is possible:
I have a mysql database 'data' and a column 'count' which contains numbers such as
3741
49215
345
4686794
I was wondering if there is a possibility to remove the last figure from each number in this column, so there will be these values:
374
4921
34
468679
(for 100,000 rows so i can't do it manually :) )
Thank you!
This will work if the field is numeric or string and is always > 0:
UPDATE `table` SET `count` = FLOOR(`count`/10)
Note single digit values will become 0
If some numbers are negative, it will not give the right answer and a substring approach like the other answers is better.
Use the MySQL SUBSTRING function to extract portion of a string. Use CHAR_LENGTH function to calculate the number of characters in the string.
SELECT
col,
SUBSTRING(col, 1, CHAR_LENGTH(col) - 1) AS col_trimme
FROM tbl
is the data type is string you can
update my_table
set my_column = substr(my_column, 1, length(my_column) -2)
if is an int you can cast
update my_table
set my_column = cast(substr(cats(my_column AS varchar(16)), 1, length(my_column AS varchar(16)) -1), AS INT)
This will work if the field is numeric or string:
UPDATE table SET count = SUBSTRING(count, 1, CHAR_LENGTH(count) - 1);
I need to get maximum number from a part of the value that generally start with year followed by slash(/). So I need a maximum number after the slash(/) but year should be 2016
2016/422
2016/423
2016/469
2016/0470
2014/777
2015/123
2015/989
I tried this query
SELECT columname FROM tablename WHERE columname LIKE '2016/%' ORDER BY id DESC
the above query always giving '2016/469' as first record, how to get '2016/0470' as the maximum number?
any help will be much appreciated.
Thank you.
If columname follows that pattern YEAR/0000, you can use SUBSTRING function from MySQL to remove the part of the string you don't want.
SELECT value FROM (
SELECT CAST(SUBSTRING(columname, 0, 4) AS UNSIGNED) as year, CAST(SUBSTRING(columname FROM 6) AS UNSIGNED) as value FROM tablename
) total
ORDER BY year DESC, value DESC
LIMIT 1;
You need to split the string into 2 parts and evaluate them as numbers, instead of strings. The following formula will return the number after the / in the fieldname. All functions used below are described in the string functions section of the MySQL documentation. This way you can get the number after the / character, even if it is not year before the /, but sg else. The + 0 converts the string to a number, eliminating any leading 0.
select right(columnname, char_length(columnname)-locate('/',columnname)) + 0
from tablename
Just take the max() of the above expression to get the expected results.
UPDATE:
If you need the original number and the result has to be restricted to a specific year, then you need to join back the results to the original table:
select columnname
from tablename t1
inner join (select max(right(t.columnname, char_length(t.columnname)-locate('/',t.columnname)) + 0) as max_num
from tablename t
where left(t.columnname,4)='2016'
) t2
on right(t1.columnname, char_length(1t.columnname)-locate('/',t1.columnname)) + 0 = t2.max_num
where left(t1.columnname,4)='2016'
There are lots of suggestions given as answers already. But some of those seem overkill to me.
Seems like the only change needed to the OP query is the expression in the ORDER BY clause.
Instead of:
ORDER BY id
We just need to order by the numeric value following the slash. And there are several approaches, several expressions, that will get that from the example data.
Since the query already includes a condition columname LIKE '2016/%'
We can get the characters after the first five characters, and then convert that string to a numeric value by adding zero.
ORDER BY SUBSTRING(columname,6) + 0 DESC
If we only want to return one row, add
LIMIT 1
http://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_substring
If we only want to return the numeric value, we could use the same expression in the SELECT list, in addition columnname.
This isn't the only approach. There are lots of other approaches that will work, and don't use SUBSTRING.
Try like this:
SELECT
MAX(CAST(SUBSTRING(t.name,
LOCATE('/', t.name) + 1)
AS UNSIGNED)) AS max_value
FROM
tablename AS t;
You can try with this little uggly approach:
SELECT t.id, t2.secondNumber FROM table AS t
JOIN (SELECT id,
CONCAT(SUBSTRING(field,1,5),
if(SUBSTRING(SUBSTRING(field, 6),1,1)='0',
SUBSTRING(field, 6),
SUBSTRING(field,7)
)
) as secondNumber FROM table ) AS t2 ON t2.id=t.id
ORDER BY t2.secondNumber DESC
Would be valid only if the 0 (zeroes) before the second number (after the slash) are no more than 1.
Or if the year doesn`t matter you can try to order them only by the second number if it is ok:
SELECT t.id, t2.secondNumber FROM table AS t
JOIN (SELECT id,
if(SUBSTRING(SUBSTRING(field, 6),1,1)='0',
SUBSTRING(field, 6),
SUBSTRING(field,7)
) as secondNumber FROM table ) AS t2 ON t2.id=t.id
ORDER BY t2.secondNumber DESC
I've got a varchar column that I want to sort numeric, which works great when using this trick: https://stackoverflow.com/a/5418033/1005334 (in short: ...ORDER BY Result * 1).
However, the table concerned contains results. So something like this occurs:
Result
------
DNS
DNF
1
2
3
The numbers are correctly ordered, but the DNF comes above the numbers when sorting like this. What I'd like is to have the numeric sort, but with non-numbers sorted alphabetically below the numbers. Like so:
Result
------
1
2
3
DNF
DNS
In what way can I modify the query (preferably only the ORDER BY clause) to get this result?
use LPAD
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_lpad
LPAD(yourField, 20, '0');
this will manage correct order for "varchar numeric fields" (10 will be after 2) and put strings at the end.
SqlFiddle
The second argument (20) is quite arbitrary. It should be equivalent to (or bigger then) the length of the longest string in your field.
SELECT *, (Result REGEXP '^[0-9]+$') AS is_numeric
FROM table_name
ORDER BY is_numeric DESC,
CASE WHEN is_numeric THEN (Result + 0) ELSE Result END ASC
You can do that by using MySQL's REGEXP. Try this one,
SELECT *
FROM tablea
ORDER BY IF(`Result` REGEXP '^-?[0-9]+$', 0, 1) ASC,
`Result` ASC
SQLFiddle Demo
try this:
Please change your ORDER BY Clause with this:
ORDER BY
CASE WHEN Result REGEXP '^[0-9]+$' THEN Result*1 else 999999 END,
Result
This will order the numeric values first then the rest
ORDER BY CAST(`Result` AS SIGNED) DESC
this should work.