I'm trying to get the Sum() from an Entityset<MyObject> with the next query.
(from MyObject p in SelectedObject.MyObjectEntitySet
where p.AColumn.HasValue &&
p.ADate >= dateTimeValue &&
p.ADate <= dateTimeValue2
select p.AColumn.Value).Sum();
with no luck retrieving correct sum.
Any Ideas?
[EDIT] OK WORKED!
You can troubleshoot the query by breaking it up into its constituent parts, and examining the output of each part:
var entitySet = SelectedObject.MyObjectEntitySet;
var entitySetWithValues = entitySet.Where(p => p.AColumn.HasValue);
var entitySetGreater = entitySetWithValues.Where(p => p.ADate >= DateTimeValue);
...and so forth.
If you see the list of overloads, the Sum method is over numeric values (decimal, float, int, double, long, etc). The selector has to be a function that takes a DateTime and returns a numeric value.
[edit]
Sorry, I didn't realize that AColumn was numeric.
Related
next problem with Linq/EF6 queries.
I simply like to build a sum of some decimal fields:
var offsetHours1 = (from os in db.TimesheetOffsets
where (os.EmployeeId == employeeId && os.OffsetDate <= DateTime.Today)
select new
{
offset = os.OffsetHours
}).Sum(h=>h.offset);
So far it works, if I have records to sum but if the query returns null or no records, I get a System.InvalidOperationException
Is there an elegant way to summarize records in one step, so if there are no records, 0 is returned?
Thanks, Carsten
There's a quirk with the Sum extension method. As OffsetHours is a decimal, the overload of Sum you'll be using is Sum(..., decimal) which has this behaviour. To avoid it you can cast the value to a decimal? (nullable). With this you'll be using a different Sum that returns a nullable decimal and is OK with empty lists;
You can for example do this;
var offsetHours1 = (from os in db.TimesheetOffsets
where (os.EmployeeId == employeeId && os.OffsetDate <= DateTime.Today)
select os.OffsetHours)
.Sum(h => (decimal?)h);
Edit:
Removed unnecessary creation of anonymous type.
It appears that [t_l_unit] being a varchar is conflicting with the filters in my Where clause. Can I fix this with a Cast of some sort?
Going by the title of your post, your are trying to convert the value "F01" to an INT?
Obviously this is not possible because of the "F" in the string.
What you can do is use the TRY_CAST function which will convert the value to an INT if it can and will return NULL otherwise
SELECT val1, va2, etc
FROM myTable
WHERE TRY_CAST([t_l_unit] as INT) = 12
The query didn't come through, but you should be able to just do:
CAST([t_l_unit] AS INT)
to use it as a number in your where clause.
I am joining the two tables using the query below:
update campaign_items
set last_modified = evt.event_time
from (
select max(event_time) event_time
,result
from events
where request = '/campaignitem/add'
group by result
) evt
where evt.result = campaign_items.id
where the result column is of character varying type and the id is of integer type
But the data in the result column contains digits(i.e. 12345)
How would I run this query with converting the type of the result(character) into id
(integer)
Well you don't need to because postgresql will do implicit type conversion in this situation. For example, you can try
select ' 12 ' = 12
You will see that it returns true even though there is extra whitespace in the string version. Nevertheless, if you need explicit conversion.
where evt.result::int = campaign_items.id
According to your comment you have values like convRepeatDelay, these obviously cannot be converted to int. What you should then do is convert your int to char!!
where evt.result = campaign_items.id::char
There are several solutions. You can use the cast operator :: to cast a value from a given type into another type:
WHERE evt.result::int = campaign_items.id
You can also use the CAST function, which is more portable:
WHERE CAST(evt.result AS int) = campaign_items.id
Note that to improve performances, you can add an index on the casting operation (note the mandatory double parentheses), but then you have to use GROUP BY result::int instead of GROUP BY result to take advantage of the index:
CREATE INDEX i_events_result ON events_items ((result::int));
By the way the best option is maybe to change the result column type to int if you know that it will only contain integers ;-)
I have this below SQL query that selects the Maximum integer value from a varchar field where the values start with MB.
select max( cast(substring( sLicenseNo, 4, len(sLicenseNo)) as int)) as licno from ApplicationForm where sLicenseNo like 'MB%'
How can I convert this lambda expression for use with entity framework ?
Try This
TestDataContext db = new TestDataContext();
var res = db.ApplicationForms.Where(y => y.sLicenseNo.Contains("MB")).Select(x => Convert.ToInt32(x.sLicenseNo.Substring(2))).Max();
Tell me if it works or not.
I'm currently trying to retrieve a single double value from this query in JOOQ Query Builder and PostgreSQL as the database, providing that DRINKS.PRICE is of type double and ORDER_DRINK.QTY is of type integer.
Record rec = create.select(DSL.sum(DRINKS.PRICE.multiply(ORDER_DRINK.QTY)).as("am_due")).from(ORDERS
.join(ORDER_DRINK
.join(DRINKS)
.on(DRINKS.DRINK_KEY.equal(ORDER_DRINK.DRINK_KEY)))
.on(ORDERS.ORDKEY.equal(ORDER_DRINK.ORDER_KEY)))
.where(ORDERS.TOKEN.eq(userToken))
.fetchOne();
As I've understood from the (brief) tutorial, once I retrieve the value from that aliased record, in the form:
double v = rec.getValue("am_due");
I should have the sum of all the prices multiplied by their quantities.
Still, I get a NullPointerException instead.
Any help would be very welcome.
Thank you.
Your jOOQ usage is correct, but I suspect that your sum is simply null because:
Your join doesn't return any records
All of your multiplication operands are null
and since you're unboxing Double to double, you're getting that NullPointerException. You can solve this
... using Java:
Double v1 = rec.getValue("am_due"); // will return null
double v2 = rec.getValue("am_due", double.class); // will return 0.0
... using jOOQ / SQL
Record rec = create.select(DSL.nvl(
DSL.sum(
DRINKS.PRICE.multiply(ORDER_DRINK.QTY)
), 0.0
).as("am_due"))