I have the following code in which I am passing a local variable to a linq query for a specific record, after that record I want to check whether there is a record according to that id or not.
First it gives me the error "Cannot implicitly convert type int to bool"
Second if I want to count the rows in this query or want to check whether there is a row or not, how will I do that, here is my code:
int J_Job_ID = Convert.ToInt32(Request.QueryString["J_Job_ID"]);
//Check If this ID exists in the database
var query = from m in JE.J_Posted_Jobs_Tbl
where m.J_Job_ID = Convert.ToInt32(J_Job_ID)
select m;
it should be
where m.J_Job_ID == Convert.ToInt32(J_Job_ID)
as for count
query.Count()
Related
I am developing a complaint management in which I have to generate unique serial number for each complaint like 00001/20 {Serial number/year}.
I am using repository pattern and i am generating this complaint number using the following code snippet but problem is if two user try to lodge a complaint at the same time it will generate a same complaint no and that thrown an error as I am keeping a serial number in a separate table which is also mentioned below for reference. Let me know the best way to achieve this
int serialNo = repository.serialNo.Find(c => c.Year == DateTime.Now.Year).FirstOrDefault().TicketCounter;
string complaintNo = string.Format("{0}", serialNo.ToString().PadLeft(5, '0'));
model.Id = repository.complaintRepo.GetMaxPK(c => c.Id);
I am using repository pattern.
I guess, one of the solutions is to setup the table so that it generates required ID automatically on every new row. This ensures that the ID is always unique.
CREATE SEQUENCE MySequence
AS int
START WITH 1
INCREMENT BY 1;
CREATE TABLE Complaint
(
Id char(8) CONSTRAINT [DF_Complaint_ID]
DEFAULT FORMAT((NEXT VALUE FOR MySequence), '0000#')
+'/'+RIGHT(YEAR(GETDATE()),2),
Foo int,
Bar int,
CONSTRAINT [PK_MyTable] PRIMARY KEY (Id)
);
Demo: https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=18a5d0fec80a3985e30cef687d3c8e49
So there will be no need to assign the id manually and your code could look like
var c = repository.Insert(new model
{
Foo = ...
Bar = ...,
...
});
repository.Save();
// you can get id after inserting data in the database
string id = c.Id;
I'm trying to query all the rows which are created the last one week. I have created an index for created key in AWS console. In my query, I added the Key Condition with ComparisonOperator.GT for the created key. But When I run the query it throws an error like Query key condition not supported. If I give the condition as ComparisonOperator.EQ, it will return a single row. But not working for the ComparisonOperator.GT.
Code :
Condition rangeKeyCondition = new Condition();
rangeKeyCondition.withComparisonOperator(ComparisonOperator.GT).withAttributeValueList(new AttributeValue().withS("11:26 23/10/2018 "));
Map<String, Condition> keyConditions = new HashMap<String, Condition>();
keyConditions.put("created", rangeKeyCondition);
QueryRequest queryRequest = new QueryRequest();
queryRequest.withTableName(getTableName(TABLE_NAME));
queryRequest.withIndexName("created-index");
queryRequest.withKeyConditions(keyConditions);
QueryResult result = EventStoreInitializer.getAmazonDynamoDBClient().query(queryRequest);
I have read your case so for your desired output you should not create 'created' as Index bz it becomes key for the table and in keyCondition you can't use GT and LT operator.
you need to use FilterExpression and there you can use GT and LT for the 'created' field.
i am creating a program with asp.net and using entity framework for sql server
MyEntitiesCONF db = new MyEntitiesCONF();
var query = (from p in db.f
join q in db.members
on p.friend_id equals q.ID
where p.uid == 1
select new
{
name = q.Name,
id = p.friend_id,
}).ToArray();
when i execute the query, i will get a {<>f__AnonymousType1[6]}
which means it is an anonymous type with 6 returns( each one have 2 field name and id )
so it is something like an 2d array
this is my question, how i can use this 2d data?
i want dynamically use each 6 ID field somewhere and name fields in other places,
any idea?
and another question, how can i get a array list, not an anonymous type
thanks
In SQLite I can run the following query to get a list of columns in a table:
PRAGMA table_info(myTable)
This gives me the columns but no information about what the primary keys may be. Additionally, I can run the following two queries for finding indexes and foreign keys:
PRAGMA index_list(myTable)
PRAGMA foreign_key_list(myTable)
But I cannot seem to figure out how to view the primary keys. Does anyone know how I can go about doing this?
Note: I also know that I can do:
select * from sqlite_master where type = 'table' and name ='myTable';
And it will give the the create table statement which shows the primary keys. But I am looking for a way to do this without parsing the create statement.
The table_info DOES give you a column named pk (last one) indicating if it is a primary key (if so the index of it in the key) or not (zero).
To clarify, from the documentation:
The "pk" column in the result set is zero for columns that are not
part of the primary key, and is the index of the column in the primary
key for columns that are part of the primary key.
Hopefully this helps someone:
After some research and pain the command that worked for me to find the primary key column name was:
SELECT l.name FROM pragma_table_info("Table_Name") as l WHERE l.pk = 1;
For the ones trying to retrieve a pk name in android, and while using the ROOM library.
#Oogway101's answer was throwing an error: "no such column [your_table_name] ... etc.. etc...
my way of query submition was:
String pkSearch = "SELECT l.name FROM pragma_table_info(" + tableName + ") as l WHERE l.pk = 1;";
database.query(new SimpleSQLiteQuery(pkSearch)
I tried using the (") quotations and still error.
String pkSearch = "SELECT l.name FROM pragma_table_info(\"" + tableName + "\") as l WHERE l.pk = 1;";
So my solution was this:
String pragmaInfo = "PRAGMA table_info(" + tableName + ");";
Cursor c = database.query(new SimpleSQLiteQuery(pragmaInfo));
String id = null;
c.moveToFirst();
do {
if (c.getInt(5) == 1) {
id = c.getString(1);
}
} while (c.moveToNext() && id == null);
Log.println(Log.ASSERT, TAG, "AbstractDao: pk is: " + id);
The explanation is that:
A) PRAGMA table_info returns a cursor with various indices, the response is atleast of length 6... didnt check more...
B) index 1 has the column name.
C) index 5 has the "pk" value, either 0 if it is not a primary key, or 1 if its a pk.
You can define more than one pk so this will not bring an accurate result if your table has more than one (IMHO more than one is bad design and balloons the complexity of the database beyond human comprehension).
So how will this fit into the #Dao? (you may ask...)
When making the Dao "abstract" you have access to a default constructor which has the database in it:
from the docummentation:
An abstract #Dao class can optionally have a constructor that takes a Database as its only parameter.
this is the constructor that will grant you access to the query.
There is a catch though...
You may use the Dao during a database creation with the .addCallback() method:
instance = Room.databaseBuilder(context.getApplicationContext(),
AppDatabase2.class, "database")
.addCallback(
//You may use the Daos here.
)
.build();
If you run a query in the constructor of the Dao, the database will enter a feedback loop of infinite instantiation.
This means that the query MUST be used LAZILY (just at the moment the user needs something), and because the value will never change, it can be stored. and never re-queried.
I want to insert a record and then update the record according to scope_identity of inserted record.
I'm doing this but when I want to update my record encounter an error.
WorkshopDataContext Dac = new WorkshopDataContext();
Dac.Connection.ConnectionString = "Data Source=dpsxxx-xxx;Initial Catalog=kar;User ID=sa;Password=xxxx";
Tbl_workshop Workshop = new Tbl_workshop();
Workshop.StateCode = Bodu.BduStateCode;
Workshop.CityCode = Bodu.BduCityCode;
Workshop.Co_workshop=12222;
Dac.Tbl_workshop.InsertOnSubmit(Workshop);
Dac.SubmitChanges();
Int64 Scope = Workshop.id;
var query = from record in Dac.Tbl_workshop where record.id == Scope select record;
query.First().co_Workshop = Scope;
Dac.SubmitChanges();
and this is the error:
Value of member 'co_Workshop' of an object of type 'Tbl_Workshop' changed.
A member defining the identity of the object cannot be changed.
Consider adding a new object with new identity and deleting the existing one instead.
If you have properly configured your Linq-to-SQL model to reflect the IDENTITY column in your table, you should have the new value available right after .SubmitChanges():
Tbl_workshop Workshop = new Tbl_workshop();
Workshop.StateCode = Bodu.BduStateCode;
Workshop.CityCode = Bodu.BduCityCode;
Workshop.Co_workshop=12222;
Dac.Tbl_workshop.InsertOnSubmit(Workshop);
Dac.SubmitChanges();
Int64 workshopID = Workshop.Id; // you should get new ID value here - automatically!!
You don't need to do anything like reading out that new value from SQL Server or anything - Linq-to-SQL should automagically update your Workshop object with the proper value.
Update: to update your co_workshop value to the value given by the IDENTITY ID, do this (just set the value of co_workshop and save again - that's really all there is):
Dac.Tbl_workshop.InsertOnSubmit(Workshop);
Dac.SubmitChanges();
Int64 workshopID = Workshop.Id; // you should get new ID value here - automatically!!
Workshop.Co_workshop = workshopID;
Dac.SubmitChanges();
As it said on the error, you can't change co_Workshop because its identity (auto increment value). To freely edit it, you need to edit the database and remove this setting.
What probably is happening is that both id and co_Workshop are set as identity. Just disable the identity checkbox from co_Workshop.