php sorting problem usng SQL ORDER BY

[peterjc]

i have a sorting problem in php using the SQL command "ORDER BY".

 

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For example:

i want to sort this number descending: 30, 4, 50, 200.

 

so in actual case we should get: 200 , 50, 30 , 4.

 

But what i get when using the ORDER BY statement is: 50, 4, 30, 200

 

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After look a while at the incorrect result, i think the problem is because it sort using the first digit of the number.

 

Anyone know how to solve this problem?

 

Thank in advance.

[AdRock]

Whatever field the numbers are in you need to so

 

ORDER BY numbers DESC

[corbin]

What datatype is the field you're sorting?

[peterjc]

Oh.  corbin, i use the char datatype for the number. i just realize it. 

 

At first i use float number datatype, but i change to char because when we total up the float number, there will be some inaccurate in php, am i correct?  How to solve this?

[teng84]

t

 

At first i use float number datatype, but i change to char because when we total up the float number, there will be some inaccurate in php, am i correct? 

 

what are those?

[peterjc]

I i total or sum all the float value using SQL statement, the total result will not accurate.

 

Just for an example:

10.6 + 12.8 = 23.4

 

but if you use SQL statement to sum it, it will output somethings like 23.3522222.(just for example).

[btherl]

To sort character column foo as an integer

 

ORDER BY foo + 0 DESC

 

ought to work..  You can also use CAST(foo AS UNSIGNED)

[peterjc]

hello btherl. 

i try to add the plus symbol(+) and zero(0) to the SQL statement and i work.  But can u explain about it.

 

And where to put CAST(foo AS UNSIGNED)

[btherl]

The other option is

 

ORDER BY CAST(foo AS UNSIGNED)

 

What happens when you add 0 to foo is that mysql is forced to convert foo into an integer.  After that, it is sorted as an integer.  The same happens when you explicitly cast foo to an integer using CAST().  "Cast" means "Change from one type to another".

 

The original problem is that your numbers were being sorted as strings, which is why it looked at the first character first, then second, and so on.

[peterjc]

Thank for your explanation, btherl.  I help me a lots.