Sorting varchar field numerically in MySQL

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 开发者_运维百科by numeric values ("9" to come before "42")?

Currently I use the query:

SELECT * FROM table ORDER BY number ASC

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Try this

SELECT * FROM table_name ORDER BY CAST(field_name as SIGNED INTEGER) ASC

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There are a few ways to do this:

1. Store them as numeric values rather than strings. You've already discounted that as you want to keep strings like 00100 intact with the leading zeros.
2. 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.
3. Add a third column which is the numeric equivalent of the string and index on that. Then use an insert/update trigger 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.

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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

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SELECT * FROM table ORDER BY number + 0

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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.

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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

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you can get order by according to your requirement my using following sql query

SELECT * FROM mytable ORDER BY ABS(mycol)

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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.

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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.

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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

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Another option to keep numerics at a top, then order by alpha.

IF(name + 0, name + 0, 9999999), name

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Rough and ready: order by 1*field_name