I have this column in a talbe which for historical reason is a string but nowdays new values are put in are numbers.
I have to find the biggest value from an interval of numbers but the values are string in the DB :(
If op_calcul would have been a number it would have been trivial sql:
Select MAX(op_calcul) FROM nom_prod where op_calcul >=500 and op_calcul < 5000
but having them as varchar put me into some trouble.
Tried different scenarios but did not come with a solution yet.
Any hint ?
Thanks
SELECT MAX(CAST(op_calcul as SIGNED)) FROM nom_prod...
Should do the trick. You might need to cast the WHERE clauses as well.
Ideally though, for performance reasons on both the MAX and the WHERE, you should use an integer column. Is there non-numeric or out of range data in it or something? It should be fairly trivial to change the column type if not.
use mysql cast to convert data into required datatypes.
http://dev.mysql.com/doc/refman/5.0/en/cast-functions.html#function_cast
Note however that it does affect query performance.
SELECT MAX(CAST(`op_calcul` AS SIGNED))
FROM `nom_prod`
WHERE `op_calcul` >= 500
AND `op_calcul` < 5000;
Related
I have a MySQL table that looks like this:
id layer l_to blank
1 1 10 xyz
0 0 5.5 xyz
I want to get the highest number of column-variable "l_to" that shares column-variable "blank".
I have tried the following SQL-query:
SELECT MAX(l_to), COUNT(layer),l_from FROM layers WHERE blank='xyz'
This works fine, if "l_to" of layer 1 is below 10. If it is ten, the query returns "l_to" from layer 0 (5.5).
Any Idea for why this is, and how can I retrieve the MAX?
#EDIT: Changing Datatype of "l_to" from VARCHAR to DECIMAL (5,1) got me the desired result. Thanks for the answers!
The datatype is not a number for field l_to so 5 is greater than 1 for a string. Probably a varchar. Change field l_to to a Decimal [1].
Only consider casting if you do not have control over the table structure as best practice is the data type reflects the data use in the world. This protects the data integrity of the database, provides helpful functions related to the datatype and ensures intuitive outcomes, like Max function. Casting as a work around for this query will only lead to downstream issues; refactor the structure now if you can.
Reference
Decimal data type suggested in comments by #Akina. Originally suggested float, but Decimal appears to reflect the Use Case better than float, given the limited examples shown.
Cast l_to from string to decimal
SELECT MAX(cast(l_to as DECIMAL(10,2)), COUNT(layer) from FROM layers WHERE blank='xyz'
Use a LIMIT query, and also cast the l_to column to decimal:
SELECT *
FROM layers
WHERE blank = 'xyz'
ORDER BY CAST(l_to AS DECIMAL(12.4)) DESC
LIMIT 1;
I've a table on ArcGis which contains nummbers and dates. I need to filter these via a sql-query. I just have the possibility to change the where clause.
See here: https://services3.arcgis.com/rKOPqLnqVBkPP9th/arcgis/rest/services/Arbeitsmappe1/FeatureServer/0//query
Just type in the where clause 1=1 and outfield * then you will get all results.
I have to filter installierte_leistung which contains numbers in the following formats:
1.050,20 ; 18; 0,1 ; 1.230
and dates of following format: 11.04.08
wished filters:
installierte_leistung: I want to execute a sql-statement like: where (installierte_leistung BETWEEN '1' AND '2'). In the result there is also the 18. Or if I ask for values greater 10 it shows me also the 1.050,20.
I tried to convert with cast and convert to decimal, signed, unsigned, integer and so on, but the query has been always invalid. I tried with 'number' and with number and with "number". lowercase and uppercase and almost all thinkable possibilities. I get no results with cast or convert.
Same issue with the Date. I want to filter monthly. so means between 01.2008 and 09.2009 for instance.
Could someone please help me? Thanks a lot!
Falk
I had a similar problem in the past with nested query. The more database specific queries (like cast and so) don't work because ArcGIS server is by default configured to work only with standardized queries. If you need to use more specific queries you have to change "standardizedQueries": "false" in server setting, check here how (bottom of the page): http://resources.arcgis.com/en/help/main/10.2/index.html#//015400000641000000. Should work for you. Good luck.
I'm trying to select all columns after a specific date but the trick is the "date" column is varchar
I have this
SELECT * FROM `users` WHERE STR_TO_DATE(birthday,'%m/%d/%Y') > '10-10-2000'
as an example and I want to select all users whos birthday is after the 10/10/2000 but this just returns all rows.
Anybody got a clue what's wrong?
You are comparing a data and a string. I would use CAST:
WHERE STR_TO_DATE(birthday,'%m/%d/%Y') > CAST('2000-10-10' AS date)
Also note that I changed the format of the second to match what mysql expects. You could also use STR_TO_DATE here.
I think mysql dates are usually yyyy-mm-dd which means you should change the string at the end to 2000-10-10.
Try that and let me know if that works.
We need to know what format the string birthday is in, now you're saying it is e.g. 12/31/2001. Is that right?
If you have multiple strings, consider using the same STR_TO_DATE-formatting:
WHERE STR_TO_DATE(birthday, '%m/%/d/%Y') BETWEEN STR_TO_DATE(some_date, '%m/%/d/%Y')
AND STR_TO_DATE(another_date, '%m/%/d/%Y')
More info:
http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_str-to-date
Is it possible to find the min value of a column of floating numbers using a mysql function? Suppose I have the following table:
id | value a | 24.88 a | 119.99
If I try:
SELECT MIN(value) FROM [table name] GROUP BY id;
mysql returns:
119.99
After testing this with different floating numbers I believe that this is the case because mysql takes the first character in each of the strings "1" and "2" and then selects a min based on which character is smaller.
I've read through this forum and others trying to find an answer but it seems nobody has raised this problem.
I should mention I've also tried CEIL(value) but that function also seems to have some bugs and I'd prefer to keep the number a floating number and not an integer.
Thanks everyone.
It looks like the column is being stored as a character-based data type. You can solve this in one of two ways:
Change the column type to a numeric type
change the query to add CAST around the value: MIN(CAST(value AS DECIMAL))
The column change might look like this:
ALTER TABLE my_table MODIFY COLUMN value double;
And, as far as I know, MySQL will attempt to convert the data for you. See the note here, which states it "tries".
This maybe an easy one but i couldn't get answer.
I need to select float value from table
example table :-
value
10.2
4.5
4.6
4.06
my query
SELECT * FROM table where value = '4.6'
returns empty result set
how can i solve this !
Generally, you should never check equality with floats (unless, potentially, you have the same object). Internally, it is represented with more precision, even if it isn't showing it to you by the time it outputs to the screen. This basic tenet holds true for computing in general.
There are a dozens of schemes for doing this, but here is a simple one, which should make sense:
SELECT * FROM table where value BETWEEN 4.599 AND 4.601
Use decimal instead of float.
A decimal(10,2) will have 2 and only 2 decimal places and can be compared in the same manner as integers.
Especially for monetairy values you should always use decimal, but anywhere where rounding errors are unwanted, decimal is a good choice.
See: http://dev.mysql.com/doc/refman/5.1/en/precision-math-decimal-changes.html
Or
MySQL DECIMAL Data Type Characteristics
Today, I also came across the same situation and get resolved just by using FORMAT function of MySQL, It will return the results that exactly match your WHERE clause.
SELECT * FROM yourtable WHERE FORMAT(`col`,2) = FORMAT(value,2)
Explanation:
FORMAT('col name',precision of floating point number)
Hope it helps.
You can also try query
SELECT * FROM table WHERE value LIKE 4.6;
you write:
SELECT * FROM table where round(value, 1) = 4.6