How can I write below sql query in linq
select * from Product where ProductTypePartyID IN
(
select Id from ProductTypeParty where PartyId = 34
)
There is no direct equivalent in LINQ. Instead you can use contains () or any
other trick to implement them. Here's an example that uses Contains:
String [] s = new String [5];
s [0] = "34";
s [1] = "12";
s [2] = "55";
s [3] = "4";
s [4] = "61";
var result = from d in context.TableName
where s.Contains (d.fieldname)
select d;
check this link for details: in clause Linq
int[] productList = new int[] { 1, 2, 3, 4 };
var myProducts = from p in db.Products
where productList.Contains(p.ProductID)
select p;
Syntactic variations aside, you can write it in practically the same way.
from p in ctx.Product
where (from ptp in ctx.ProductTypeParty
where ptp.PartyId == 34
select ptp.Id).Contains(p.ProductTypePartyID)
select p
I prefer using the existential quantifier, though:
from p in ctx.Product
where (from ptp in ctx.ProductTypeParty
where ptp.PartyId == 34
&& ptp.Id == p.ProductTypePartyID).Any()
select p
I expect that this form will resolve to an EXISTS (SELECT * ...) in the generated SQL.
You'll want to profile both, in case there's a big difference in performance.
Something similar to this
var partyProducts = from p in dbo.Product
join pt in dbo.ProductTypeParty on p.ProductTypePartyID equal pt.PartyId
where pt.PartyId = 34
select p
You use the Contains in a Where clause.
Something along these lines (untested):
var results = Product.Where(product => ProductTypeParty
.Where(ptp => ptp.PartyId == 34)
.Select(ptp => ptp.Id)
.Contains(product.Id)
);
Related
How can I convert this query to Entity Framework Query?
select Price,
(
select Cost.Title
from Cost
where Cost.CostID= CostItem.CostID
) as nameCost
from CostItem
where ItemID= 11
var result = dbContext.CostItems
.Where(item => item.ItemId == 11)
.Select(item => new { Price = item.Price, nameCose = item.Cost.Title })
Just make sure you have you relations in entity objects properly set up
Your query can also be written with a LEFT JOIN:
SELECT
ci.Price,
NameCost = c.Title
FROM CostItem ci
LEFT JOIN Cost c
ON c.CostID = ci.CostID
WHERE ci.ItemID = 11
Converting this to Linq using C#, you get:
var t =
from ci in CostItem
join c in Cost on ci.CostID equals c.CostID into lc
from c in lc.DefaultIfEmpty()
where ci.ItemID == 11
select new {
Price = ci.Price,
NameCost = c.Title
};
I am trying to write a dapper query for IN clause, but it's not working throwing casting error saying "Conversion failed when converting the nvarchar value 'A8B08B50-2930-42DC-9DAA-776AC7810A0A' to data type int." . In below query fleetAsset is Guid converted into string.
public IQueryable<MarketTransaction> GetMarketTransactions(int fleetId, int userId, int rowCount)
{
//Original EF queries which I am trying to convert to Dapper
//var fleetAsset = (from logicalFleetNode in _context.LogicalFleetNodes
// where logicalFleetNode.LogicalFleetId == fleetId
// select logicalFleetNode.AssetID).ToList();
////This query fetches guid of assetprofiles for which user having permissions based on the assets user looking onto fleet
//var assetProfileIds = (from ap in _context.AssetProfileJoinAccounts
// where fleetAsset.Contains(ap.AssetProfile.AssetID) && ap.AccountId == userId
// select ap.AssetProfileId).ToList();
var fleetAsset = _context.Database.Connection.Query<string>("SELECT CONVERT(varchar(36),AssetID) from LogicalFleetNodes Where LogicalFleetId=#Fleetid",
new { fleetId }).AsEnumerable();
//This query fetches guid of assetprofiles for which user having permissions based on the assets user looking onto fleet
var sql = String.Format("SELECT TOP(#RowCount) AssetProfileId FROM [AssetProfileJoinAccounts] AS APJA WHERE ( EXISTS (SELECT " +
"1 AS [C1] FROM [dbo].[LogicalFleetNodes] AS LFN " +
"INNER JOIN [dbo].[AssetProfile] AS AP ON [LFN].[AssetID] = [AP].[AssetID]" +
" WHERE ([APJA].[AssetProfileId] = [AP].[ID]) " +
" AND ([APJA].[AccountId] = #AccountId AND LogicalFleetId IN #FleetId)))");
var assetProfileIds = _context.Database.Connection.Query<Guid>(sql, new { AccountId = userId, FleetId = fleetAsset, RowCount=rowCount });
Dapper performs expansion, so if the data types match, you should just need to do:
LogicalFleetId IN #FleetId
(note no parentheses)
Passing in a FleetId (typically via an anonymous type like in the question) that is an obvious array or list or similar.
If it isn't working when you remove the parentheses, then there are two questions to ask:
what is the column type of LocalFleetId?
what is the declared type of the local variable fleetAsset (that you are passing in as FleetId)?
Update: test case showing it working fine:
public void GuidIn_SO_24177902()
{
// invent and populate
Guid a = Guid.NewGuid(), b = Guid.NewGuid(),
c = Guid.NewGuid(), d = Guid.NewGuid();
connection.Execute("create table #foo (i int, g uniqueidentifier)");
connection.Execute("insert #foo(i,g) values(#i,#g)",
new[] { new { i = 1, g = a }, new { i = 2, g = b },
new { i = 3, g = c },new { i = 4, g = d }});
// check that rows 2&3 yield guids b&c
var guids = connection.Query<Guid>("select g from #foo where i in (2,3)")
.ToArray();
guids.Length.Equals(2);
guids.Contains(a).Equals(false);
guids.Contains(b).Equals(true);
guids.Contains(c).Equals(true);
guids.Contains(d).Equals(false);
// in query on the guids
var rows = connection.Query(
"select * from #foo where g in #guids order by i", new { guids })
.Select(row => new { i = (int)row.i, g = (Guid)row.g }).ToArray();
rows.Length.Equals(2);
rows[0].i.Equals(2);
rows[0].g.Equals(b);
rows[1].i.Equals(3);
rows[1].g.Equals(c);
}
I have a Code column of type varchar in database, which includes numbers only. I use the method below to get the next code, and it works fine. But I prefer all the calculations and type conversions to be done on SQL side, to have less overhead. Using the code below, I retrieve all data, which is not needed. Any ideas is really appreciated.
public string GetNextCode(int type)
{
var codeList = (from o in ObjectQuery
where o.Type == Type
select o.Code).ToList<string>();
List<int> list = codeList.Select(int.Parse).ToList();
int nextDL = list.Max() + 1;
return nextDL.ToString();
}
You could try something like the below, it orders the result set descending by the Code and then grabs the first result. Please note I haven't tested this but I think it should work.
var codeList = (from o in ObjectQuery
where o.Type == Type
select o.Code).OrderByDescending(
x => x.Code).First()
Instead of OrderByDescending().First() you could also use OrderBy().Last()
This is a solution I came up with:
var max = (from o in ObjectQuery
let num = ObjectQuery.Where(i => i.Type == Type).Select(i => i.Code).Cast<int>().Max()
select num).FirstOrDefault() + 1;
return max.ToString();
Disclaimer: not my code, not my database design!
I have a column of censusblocks(varbinary(max), null) in a MS SQL Server 2008 db table (call it foo for simplicity).
This column is actually a null or 1 to n long list of int. The ints are actually foreign keys to another table (call it censusblock with a pk id of type of int), numbering from 1 to ~9600000.
I want to query to extract the censusblocks list from foo, and use the extracted list of int from each row to look up the corresponding censusblock row. There's a long, boring rest of the query that will be used from there, but it needs to start with the census blocks pulled from the foo table's censusblocks column.
This conversion-and-look-up is currently handled on the middle tier, with a small .NET utility class to convert from List<int> to byte[] (and vice versa), which is then written into/read from the db as varbinary. I would like to do the same thing, purely in SQL.
The desired query would go something along the lines of
SELECT f.id, c.id
FROM foo f
LEFT OUTER JOIN censusblock c ON
c.id IN f.censusblocks --this is where the magic happens
where f.id in (1,2)
Which would result in:
f.id | c.id
1 8437314
1 8438819
1 8439744
1 8441795
1 8442741
1 8444984
1 8445568
1 8445641
1 8447953
2 5860657
2 5866881
2 5866881
2 5866858
2 5862557
2 5870475
2 5868983
2 5865207
2 5863465
2 5867301
2 5864057
2 5862256
NB: the 7-digit results are coincidental. The range is, as stated above, 1-7 digits.
The actual censusblocks column looks like
SELECT TOP 2 censusblocks FROM foo
which results in
censublocks
0x80BE4280C42380C7C080CFC380D37580DC3880DE8080DEC980E7D1
0x596D3159858159856A59749D59938B598DB7597EF7597829598725597A79597370
For further clarification, here's the guts of the .NET utility classes conversion methods:
public static List<int> getIntegersFromBytes(byte[] data)
{
List<int> values = new List<int>();
if (data != null && data.Length > 2)
{
long ids = data.Length / 3;
byte[] oneId = new byte[4];
oneId[0] = 0;
for (long i = 0; i < ids; i++)
{
oneId[0] = 0;
Array.Copy(data, i * 3, oneId, 1, 3);
if (BitConverter.IsLittleEndian)
{ Array.Reverse(oneId); }
values.Add(BitConverter.ToInt32(oneId, 0));
}}
return values;
}
public static byte[] getBytesFromIntegers(List<int> values)
{
byte[] data = null;
if (values != null && values.Count > 0)
{
data = new byte[values.Count * 3];
int count = 0;
byte[] idBytes = null;
foreach (int id in values)
{
idBytes = BitConverter.GetBytes(id);
if (BitConverter.IsLittleEndian)
{ Array.Reverse(idBytes); }
Array.Copy(idBytes, 1, data, count * 3, 3);
count++;
} }
return data;
}
An example of how this might be done. It is unlikely to scale brilliantly.
If you have a numbers table in your database it should be used in place of nums_cte.
This works by converting the binary value to a literal hex string, then reading it in 8-character chunks
-- create test data
DECLARE #foo TABLE
(id int ,
censusblocks varbinary(max)
)
DECLARE #censusblock TABLE
(id int)
INSERT #censusblock (id)
VALUES(1),(2),(1003),(5030),(5031),(2),(6)
INSERT #foo (id,censusblocks)
VALUES (1,0x0000000100000002000003EB),
(2,0x000013A6000013A7)
--query
DECLARE #biMaxLen bigint
SELECT #biMaxLen = MAX(LEN(CONVERT(varchar(max),censusblocks,2))) FROM #foo
;with nums_cte
AS
(
SELECT TOP (#biMaxLen) ((ROW_NUMBER() OVER (ORDER BY a.type) - 1) * 8) AS n
FROM master..spt_values as a
CROSS JOIN master..spt_values as b
)
,binCTE
AS
(
SELECT d.id, CAST(CONVERT(binary(4),SUBSTRING(s,n + 1,8),2) AS int) as cblock
FROM (SELECT Id, CONVERT(varchar(max),censusblocks,2) AS s FROM #foo) AS d
JOIN nums_cte
ON n < LEN(d.s)
)
SELECT *
FROM binCTE as b
LEFT
JOIN #censusblock c
ON c.id = b.cblock
ORDER BY b.id, b.cblock
You could also consider adding your existing .Net conversion methods into the database as an assembly and accessing them through CLR functions.
This is off-topic, but I couldn't resist writing these conversions so they use IEnumerables instead of arrays and Lists. This might not be faster per se, but is more general and would allow you to perform the conversion without loading the whole array at once, which may be helpful if the arrays you are dealing with are large.
Here it is, for what it's worth:
static IEnumerable<int> BytesToInts(IEnumerable<byte> bytes) {
var buff = new byte[4];
using (var en = bytes.GetEnumerator()) {
while (en.MoveNext()) {
buff[0] = en.Current;
if (en.MoveNext()) {
buff[1] = en.Current;
if (en.MoveNext()) {
buff[2] = en.Current;
if (en.MoveNext()) {
buff[3] = en.Current;
if (BitConverter.IsLittleEndian)
Array.Reverse(buff);
yield return BitConverter.ToInt32(buff, 0);
continue;
}
}
}
throw new ArgumentException("Wrong number of bytes.", "bytes");
}
}
}
static IEnumerable<byte> IntsToBytes(IEnumerable<int> ints) {
if (BitConverter.IsLittleEndian)
return ints.SelectMany(
b => {
var buff = BitConverter.GetBytes(b);
Array.Reverse(buff);
return buff;
}
);
return ints.SelectMany(BitConverter.GetBytes);
}
Your code seems to like encoding an int into 3 bytes instead of 4, which would cause problems with values that don't fit into 3 bytes (including negatives) - is that intentional?
BTW, you should be able to adapt this (or your) code for execution in SQL Server CLR. This is not exactly "in SQL", but is "in DBMS".
you can use Convert(int, censusBlock) to convert the varchar value to int value.
the you can join on that column.
Or have i misunderstood the question?
I have specific SQL expression :
{
select * from courceMCPD.dbo.Contact c
where c.cID in ( select cId from courceMCPD.dbo.Friend f where f.cId=5)
}
i would like to get LINQ expression that gets the same result.
thank you in advance.
That sounds like it's equivalent to something like:
var friendIds = from friend in db.Friends
where friend.ContactId == 5
select friend.ContactId;
var query = from contact in db.Contacts
where friendIds.Contains(contact.Id)
select contact;
(There are lots of different ways of representing the query, but that's the simplest one I could think of.)
It's pretty odd to perform a join on a particular field and also mandate that that field has to have a particular value though... there's not very much difference between that and:
var query = db.Contacts.Where(c => c.Id == 5);
... the only difference is whether there are any friend entries for that particular contact.
EDIT: Smudge gave another option for the query in a comment, so I'm promoting it into this answer...
var query = db.Contacts.Where(c => c.Friends.Any(f => f.cId == 5))
This assumes you've got an appropriate Friends relationship defined in the Contacts entity.
Using labda expressions:
var query = dc.Contact
.Where(c => dc.Friend.Select(f => f.cId).Contains(i.cID))
.Where(c => c.cId == 5);
User "query" syntax:
var query = from c in dc.Contact
where (from f in dc.Friend select f.cID).Contains(c.cId)
where c.cId == 5
select c;
You haven't specified VB/C# so I'm going for VB =P
Dim results As IEnumerable(Of yourEntities.Contact) =
(From c In yourContextInstance.Contacts Where (From f In yourContextInstance.Friends
Where f.cId = 5 Select f.cId).Contains(c.cID))
Clearly, Jon's answer works, this query (I believe) just resembles your T-SQL Closer.