I would like to return all rows from TableA table that does not exists in another table.
e.g.
select bench_id from TableA where bench_id not in (select bench_id from TableB )
can you please help me write equivalent LINQ query. Here TableA is from Excel and TableB is from a Database
I am loading Excel sheet data into DataTable, TableA. TableB I am loading from Database. In short, TableA and TableB is type of DataTable
So if table A is from Excel, are you loading the data into memory first? If so (i.e. you're using LINQ to Objects) then I suggest you load the IDs in table B into a set and then use:
var query = tableA.Where(entry => !tableBIdSet.Contains(entry.Id));
If this isn't appropriate, please give more details.
Converting into a set is probably best done just by using the HashSet constructor which takes an IEnumerable<T>. For example:
var tableBIdSet = new HashSet<string>(db.TableB.Select(entry => entry.Id));
(If the IDs aren't actually distinct, you could add a call to Distinct() at the end.)
var lPenaltyEmployee = from row1 in tBal.getPenaltyEmployeeList().AsEnumerable()
select row1;
var PenaltyEmp = new HashSet<string>(lPenaltyEmployee.Select(Entry => Entry.Emsrno);
DataTable lAbsentEmp = (from row in tBal.getAbsentEmployee(txtFromDate.Text).AsEnumerable()
where !(PenaltyEmp).Contains(row["Emsrno"].ToString())
select row).CopyToDataTable();
From a in TableA
Group Join b in TableB on a.bench_id Equalsb.bench_id into g = Group
Where g.Count = 0
Select a
Related
I have 2 tables.
This is tableA
(invoice,D/O, cost..) and
Table B
(D/O, GRN, Qty)
Now how to use query to show table A include GRN,Qty
See
You need a LEFT OUTER JOIN to retrieve all the records from table A with matched records from table B.
Guessing at the join criteria because your question doesn't say what they are:
select a.*
, b.grn
, b.grn_line
, b.qty_grn
from a
left outer join b
on a.do = b.do
and a.do_line = b.do_line
and a.invoice_line = b.grn_line
I have a table pa_master_details and lov_details.
In the pa_master_details table, I have role_comp_emp_final_rating and role_comp_lm_final_rating columns.
In the lov_details table I have a column rating lov_value and lov_text_en.
I need to join role_comp_emp_final_rating with the lov_value column to get lov_text_en
Based on this lov_value, I need to show lov_text_en from the lov_details table.
So I wrote a query like this and am getting the result for emp rating:
SELECT p.employee_number,
p.role_comp_emp_final_rating,
lov_text_en,
p.role_comp_lm_final_rating
FROM pa_master_details P, lov_details L
WHERE p.role_comp_emp_final_rating = l.lov_value
AND p.employee_number = 34570
Similarly, I need to show lov_text_en for role_comp_lm_final_rating from the lov_details table by joining
role_comp_lm_final_rating with lov_value in the same query.
How do I do it?
I think this is what you're asking for:
SELECT p.employee_number,
p.role_comp_emp_final_rating,
lemp.lov_text_en AS "emp_lov_text",
llm.lov_text_en AS "lm_lov_text",
p.role_comp_lm_final_rating
FROM pa_master_details p
JOIN (SELECT lov_text FROM lov_details) lemp ON p.role_comp_emp_final_rating = lemp.lov_value
JOIN (SELECT lov_text FROM lov_details) llm ON p.role_comp_lm_final_rating = llm.lov_value
WHERE p.employee_number = 34570
I do know update clause doesn't work with joins in Oracle.
update table1 Pr
set code = (select t2.class_attr_value from table2 t2
where class_attr_name = 'sample' and Pr.epcclass_id = t2.epcclass_id)
I would be thankful if someone can help me modify my query so that I don't get the error of SQL Command not ended properly.
Your Query seems okay to me I just added Table Alias. Your query will update all records in table1. What error you are getting...??
Suggestions,
a) Unless it's the intent that you want to update all records, add a where clause in the query to avoid updating all records...
b) If you are getting (ORA-01427: single-row subquery returns more than one row) then means corelated sub query (within brackets) is missing some condition to make it fetch only 1 row per epcclass_id.
update table1 Pr
set Pr.code = (select t2.class_attr_value
from table2 t2
where t2.class_attr_name = 'sample'
and t2.epclass_id = Pr.epcclass_id
);
Try this:
UPDATE table1 Pr INNER JOIN table2 t2
ON t2.class_attr_name = 'sample' AND Pr.epcclass_id = t2.epcclass_id
SET Pr.code = t2.class_attr_value
I need the fields in 1 table contingent on 1 property matching rows in another table.
I can write this query in SQL with a subquery as such:
SELECT *
FROM Table1
WHERE Property1 IN
(
SELECT Property1
FROM Table2
WHERE Property0 = 1
)
But I read here that it's less complicated and just as easy to write with a join, which I did. However, so far I'm unable to return just Table1 as I'd like since I'm using a join, which if I'm not mistaken, requires me to create this anonymous type, as below. What I did here works (I created another object with the same properties of Table1 I need), but I can't help thinking there's a better way to do this.
Table1.Join(Table2, t1 => t1.Property1, t2 => t2.Property1, (t1, t2) => new
{
t1.Property1,
t1.Property2,
t1.Property3
})
.Select(ob => new UnnecessaryObject
{
Property1 = ob.Property1,
Property2 = ob.Property2,
Property3 = ob.Property3
}
I also tried just creating a Table1 in the .Select part, but I got an error about explicit construction not being allowed.
Just to clarify, I'd like to be able to return the IQueryable of type Table1, which it seems like I ought to be able to do without having to create UnnecessaryObject...but I'm still pretty new to LINQ, so I'd appreciate any help you can offer. Thanks in advance.
You could just do:
from t1 in table1
join t2 in table2 on t1.property1 equals t2.property1
select t1;
That would return a collection of table1 objects. This assumes from your example table1 is a collection of table1 objects and table2 is a collection of table2 objects.
The best translation of your original query I can come up with is:
from item in context.Table1
where context.Table2
.Where(x => x.Property0 == 0)
.Any(x => x.Property1 == item.Property1)
select item
This selects all items from Table1, where there's an item with matching Property1 and Property0 == 0 from Table2
It can also be solved with a join indeed. To get an efficient join, you need to have a relation between the two tables. Then you can do something like assuming the relation is called RelatedItems:
from item in context.Table1
join relatedItem in item.RelatedItems
on item.Property1 equals relatedItem.Property
where relatedItem.Property0 == 0
select item
This is equivalent to the SQL:
SELECT *
FROM Table1
JOIN Table2 ON Table1.Property1 = Table2.Property1
WHERE Table2.Property0 = 0
I have the following Linq statement:
(from order in Orders.AsEnumerable()
join component in Components.AsEnumerable()
on order.ORDER_ID equals component.ORDER_ID
join detail in Detailss.AsEnumerable()
on component.RESULT_ID equals detail.RESULT_ID
where orderRestrict.ORDER_MNEMONIC == "MyOrderText"
select new
{
Mnemonic = detail.TEST_MNEMONIC,
OrderID = component.ORDER_ID,
SeqNumber = component.SEQ_NUM
}).ToList()
I expect this to put out the following query:
select *
from Orders ord (NoLock)
join Component comp (NoLock)
on ord .ORDER_ID = comp.ORDER_ID
join Details detail (NoLock)
on comp.RESULT_TEST_NUM = detail .RESULT_TEST_NUM
where res.ORDER_MNEMONIC = 'MyOrderText'
but instead I get 3 seperate queries that select all rows from the tables. I am guessing that Linq is then filtering the values because I do get the correct values in the end.
The problem is that it takes WAY WAY too long because it is pulling down all the rows from all three tables.
Any ideas how I can fix that?
Remove the .AsEnumerable()s from the query as these are preventing the entire query being evaluated on the server.