I have a field number of type varchar. Even though it is of type varchar, it stores integer values with optional leading zeros. A sort orders them lexicographically ("42" comes before "9"). How can I order by numeric values ("9" to come before "42")?
Currently I use the query:
SELECT * FROM table ORDER BY number ASC
Answers:
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Method 1
Try this
SELECT * FROM table_name ORDER BY CAST(field_name as SIGNED INTEGER) ASC
Method 2
There are a few ways to do this:
- Store them as numeric values rather than strings. You’ve already discounted that as you want to keep strings like
00100intact with the leading zeros. - Order by the strings cast as numeric. This will work but be aware that it’s a performance killer for decent sized databases. Per-row functions don’t really scale well.
- Add a third column which is the numeric equivalent of the string and index on that. Then use an
insert/updatetrigger to ensure it’s set correctly whenever the string column changes.
Since the vast majority of databases are read far more often than written, this third option above amortises the cost of the calculation (done at insert/update) over all selects. Your selects will be blindingly fast since they use the numeric column to order (and no per-row functions).
Your inserts and updates will be slower but that’s the price you pay and, to be honest, it’s well worth paying.
The use of the trigger maintains the ACID properties of the table since the two columns are kept in step. And it’s a well-known idiom that you can usually trade off space for time in most performance optimisations.
We’ve used this “trick” in many situations, such as storing lower-cased versions of surnames alongside the originals (instead of using something like tolower), lengths of identifying strings to find all users with 7-character ones (instead of using len) and so on.
Keep in mind that it’s okay to revert from third normal form for performance provided you understand (and mitigate) the consequences.
Method 3
Actually i’ve found something interesting:
SELECT * FROM mytable ORDER BY LPAD(LOWER(mycol), 10,0) DESC
This allows you to order the field like:
1 2 3 10 A A1 B2 10A 111
Method 4
SELECT * FROM table ORDER BY number + 0
Method 5
Trick I just learned. Add ‘+0’ to the varchar field order clause:
SELECT * FROM table ORDER BY number+0 ASC
I now see this answer above. I am wondering if this is typecasting the field and an integer. I have not compared performance. Working great.
Method 6
For a table with values like Er353, ER 280, ER 30, ER36
default sort will give
ER280
ER30
ER353
ER36
SELECT fieldname, SUBSTRING(fieldname, 1, 2) AS bcd,
CONVERT(SUBSTRING(fieldname, 3, 9), UNSIGNED INTEGER) AS num
FROM table_name
ORDER BY bcd, num;
the results will be in this order
ER30
ER36
ER280
ER353
Method 7
you can get order by according to your requirement my using following sql query
SELECT * FROM mytable ORDER BY ABS(mycol)
Method 8
given a column username containing VARCHAR‘s like these:
username1 username10 username100
one could do:
SELECT username,
CONVERT(REPLACE(username, 'username', ''), UNSIGNED INTEGER) AS N
FROM users u
WHERE username LIKE 'username%'
ORDER BY N;
it is not cheap, but does the job.
Method 9
SELECT * FROM table ORDER BY number ASC
Should display what you want it to display.. looks like you’re sorting it by id or number is not defined as integer at the moment.
Method 10
MySQL ORDER BY Sorting alphanumeric on correct order
example:
SELECT `alphanumericCol` FROM `tableName` ORDER BY SUBSTR(`alphanumericCol` FROM 1 FOR 1), LPAD(lower(`alphanumericCol`), 10,0) ASC
output:
0 1 2 11 21 100 101 102 104 S-104A S-105 S-107 S-111
Method 11
Rough and ready: order by 1*field_name
All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0