Below I am using substring index within max attribute in select statement to get max value from a column. But below code works fine for single digits after second dash but it doesn't retrieve value for double digit values after second dash.
Below is the query what i am using
select max(SUBSTRING_INDEX(pid,"-",-1)) from patient;
Values stored in column are of pattern as shown below
P-29082017-1,
P-29082017-2,
...
P-29082017-9,
P-29082017-10
The above query returns only single digit, i,e if i have 10 entries say pid from 1 to 10 listed in column, Value i am getting back from the above query is 9 and not 10
Please suggest where i am going wrong with the query
I think your max() function is being evaluated in string context rather than numeric context. In string context, 9 comes after 10.
So try this. It will turn SUBSTRING() output into numbers.
SELECT MAX(CAST(SUBSTRING_INDEX(pid,'-',-1) AS INT))
Related
I have tried to select something with SQL, and I've a problem with it.
What I want:
SQL SELECT * FROM table WHERE ? = '5';
Select everything which = 5, BUT not specify from which column.
Example:
From this ""database"", you should receive the 1st and the last row.
Is that possible?
You have to list the columns but you can use in. The where clause looks like:
where 5 in (price, height)
Note: This assumes that the columns have the same type. You could get type conversion errors if they are not.
Also, given the names of the column and the data, I assume that the columns are stored as numbers. Hence, I dropped the single quotes around 5. If they are really strings, then use the single quotes.
you need to add a condition to your query with or keyword so if any of them match the row will be shown as a result
SELECT * FROM tablename WHERE price =5 or height= 5
better you list your columns by name instead of using * after SELECT
I have above table and I want to get the highest value from table bids where bid_id=60 using the following query
SELECT MAX(offer_amount) as maz FROM bids WHERE bid_id = 60
The problem is I'm getting the result as 80 in instead of the correct value which is 7000000
Anybody with an idea of how to solve this?
Store offer_amount in a numeric field (such as integer or decimal), not as text. Quick solution is to use the CAST() function in the query to cast the field's data type to a numeric one.
I have amounts stored as a varchar in my table.
When attempting to sum them it always returns 0.00.
Below is an example using only one record from the db.
SELECT col1, SUM(CAST(col2 AS DECIMAL(20,2))) derived1
FROM table
WHERE col3 = 'FIT'
AND col1 = '6211195'
GROUP BY col1
This returns one row with a 0 value.
By removing the SUM and CAST from the query, I can see that it is pulling the value as it should, but I can not sum or cast it, adding either of those breaks it and returns 0 again.
I have also tried converting the field to a decimal type and it just zeros all the values.
EDIT:
Ughh, I just ran a REGEX query to detect anything that isnt an alphanumeric value or a decimal point. It appears that there are non ascii characters in the field that I cant see, messing with the type casting. Will continue to update as I learn more.
Show some sample values of col2. A string that really is a number is treated as a number. Hence '1' will become 1.
However, if the string does not start with a digit, '-', or '+' (after leading spaces), then it will be 0 (in most cases). So 'A1' will be 0. And so on. As will '$100'.
The lesson is: If a column contains numbers, store them as numbers. Really simple.
I am trying to understand the usage of Substring query in mysql
Here is the query that i tried.
select substr('Beautiful',-5) from dual; //output tiful
Is it that when we are giving a negative value, the count is done from the last character..
At the same time when i give the following query
select substr('Beautiful',-5,2) from dual; // outputs ti
Is it that when we are giving a negative value, the count is done from the last character and displays the values 5 and 6 i.e (t & i)..
The problem arises when i the following query
select substr('Beautiful',-5,-2) from dual; // outputs <blank>
I was actually expecting the output as "ut". ; can anyone explain me what is happening here, Is my assessment for the above two queries correct ?
Assuming you're using MySQL 5.x, for function SUBSTRING(str,pos,len) , 3rd parameter len is a non-negative integer > 0. Any other value will result in empty string.
If len is less than 1, the result is the empty string.
Reference: http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substr
I have an events table with a field called breaks. This is populated with data in a comma separated format, i.e. 1,2,3 or 1 or 1,4,5 - the same format that MySQL's IN command uses.
I'd then like to run a query - on the slots table - to return all rows apart from those specified in events.breaks.
The query, theoretically, should be something like this:
SELECT
`slots`.`id` AS id,
RIGHT(`slots`.`time`, 8) AS `time`
FROM
`slots`, `event`
WHERE
`slots`.`id` NOT IN (`event`.`breaks`)
But that doesn't appear to work - if event.breaks is 4,5,7, the only row from the slots table that doesn't return is 4!
SQLFiddle here: http://sqlfiddle.com/#!2/913fe/1/0
You're passing a single field to the NOT IN () clause, not a subexpression. Think of it like this
(1, 2, 3)
is roughly the same as
SELECT 1
UNION
SELECT 2
UNION
SELECT 3;
as a subexpression. What you're doing instead is
('4,5,7')
which is roughly equivalent to
SELECT '4,5,7';
which in turn MySQL probably converted to a number for the comparison and the result is
NOT IN (4)
What you're actually trying to do isn't really supposed to be done like that. It'd be better if you added an AxB relation table so you can select several rows with the IDs you don't want.
Give this a try:
SELECT slots.id AS id, RIGHT(slots.time, 8) time
FROM slots, event
WHERE FIND_IN_SET(slots.id, event.breaks) = 0
This is how the FIND_IN_SET(str,strlist) function works:
Returns a value in the range of 1 to N if the string str is in the string list strlist consisting of N substrings. A string list is a string composed of substrings separated by “,” characters. [...] Returns 0 if str is not in strlist or if strlist is the empty string.
Also note that IN (val1, val2, val3) is NOT the same as IN (val4) where val4 is a commma-separated string. The IN clause will compare by equality.
you may need a subselect to return the split string
... NOT IN (SELECT your_split_fnc(`event`.`breaks`) FROM `events`)
See answers here for a way to split strings in MySQL Can Mysql Split a column?
instr() MySQL function could be of help also
... INSTR(event.breaks,id) = 0
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_instr