I don't understand why linq2db is not generating the correct SQL string for this query against Oracle, and it is working perfectly against SQLServer.
string idUser="U1";
await context.Users.ToLinqToDbTable().Where(u=>u.IdUser == idUser).FirstOrDefaultAsyncLinqToDB();
Always returns null. However, it works if el value used directly:
await context.Users.ToLinqToDbTable().Where(u=>u.IdUser == "U1").FirstOrDefaultAsyncLinqToDB();
Looking at the logs, el SQL statement generated is like this:
-- Oracle Oracle11
DECLARE #idUser Varchar2(8) -- String
SET #idUser = 'U1'
SELECT
u.IdUser,
etc..
FROM
USERS u
WHERE
u.IDUSER = :idUser
Why is it generating T-SQL code and not Oracle code (the context is initialized with .UseOracle())?
Thanks
Related
I have a stored procedure that loads data and returns on record in a string format. How do I call it and capture the result using NHibernate
Eg below
var query = session.CreateSQLQuery("EXECUTE LoadData #ActualsDate =:ActualsDate, ActualBroadcastMonth =:ActualsMonth")
.SetTimeout(0)
.SetParameter("ActualsDate", actualsDate)
.SetParameter("ActualsMonth", actualsMonth)
.???;
return ...;```
Got the answer
.SetTimeout(0)
.SetParameter("ActualsDate", actualsDate)
.SetParameter("ActualsMonth", actualsMonth)
.UniqueResult;
return query.ToString();
I have been able to link PostgreSQL to java. I have been able to display all the records in the table, however I unable to perform delete operation.
Here is my code:
con = DriverManager.getConnection(url, user, password);
String stm = "DELETE FROM hostdetails WHERE MAC = 'kzhdf'";
pst = con.prepareStatement(stm);
pst.executeUpdate();
Please note that MAC is a string field and is written in capital letters. This field does exist in the table.
The error that I am getting:
SEVERE: ERROR: column "mac" does not exist
When it comes to Postgresql and entity names (Tables, Columns, etc.) with UPPER CASE letters, you need to "escape" the word by placing it in "". Please refer to the documentation on this particular subject. So, your example would be written like this:
String stm = "DELETE FROM hostdetails WHERE \"MAC\" = 'kzhdf'";
On a side note, considering you are using prepared statements, you should not be setting the value directly in your SQL statement.
con = DriverManager.getConnection(url, user, password);
String stm = "DELETE FROM hostdetails WHERE \"MAC\" = ?";
pst = con.prepareStatement(stm);
pst.setString(1, "kzhdf");
pst.executeUpdate();
I am totally confused regarding how to use Stored Procedures using Entity Framework Core. If the stored procedure return an anonymous type, how do I retrieve the data? If the return type is not anonymous, what should I do? How do I add input/output parameters?
I am asking these questions because everywhere I look, I get a different answer. I guess EF Core is evolving rapidly and Microsoft is dabbling with a lot of ideas.
How do I add input/output parameters?
I'm going to answer this particular question of yours.
Below is a TSQL stored procedure with two input and two output parameters
CREATE PROCEDURE [dbo].[yourstoredprocedure]
-- Add the parameters for the stored procedure here
#varone bigint
,#vartwo Date
,#varthree double precision OUTPUT
,#varfour bigint OUTPUT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- YOUR CODE HERE
SET #varthree = 10.02;
SET #varfour = #varone;
return;
END
Now To execute this stored procedure using Entity Framework Core
MyContext.Database
.ExecuteSqlCommand(#"EXECUTE [yourstoredprocedure] " +
" {0} " +
", {1} " +
",#varthree OUTPUT " +
", #varfour OUTPUT ", dataOne, dataTwo, outputVarOne, outputVarTwo);
var outputResultOne= outputVarOne.Value as double?;
var outputResultTwo= outputVarTwo.Value as long?;
You can pass your input simply using parameterized query as above. You can also create named parameters. such as for output parameters, I've created two named parameters as -
var outputVarOne = new SqlParameter
{
ParameterName = "#varthree ",
DbType = System.Data.DbType.Double,
Direction = System.Data.ParameterDirection.Output
};
var outputVarTwo = new SqlParameter
{
ParameterName = "#varfour ",
DbType = System.Data.DbType.Int64,
Direction = System.Data.ParameterDirection.Output
};
And This is how using EF Core you execute a stored procedure with input and output parameters. Hope this helps someone.
This solution provides methods that call a stored procedure and maps the returned value to a defined (non-model) entity. https://github.com/verdie-g/StoredProcedureDotNetCore
Microsoft address this issue:
"SQL queries can only be used to return entity types that are part of your model. There is an enhancement on our backlog to enable returning ad-hoc types from raw SQL queries." https://learn.microsoft.com/en-us/ef/core/querying/raw-sql
And here is the issue tracked in GitHub: https://github.com/aspnet/EntityFramework/issues/1862
you might use an extention like StoredProcedureEFCore
Then the usage is more intuitively.
List rows = null;
ctx.LoadStoredProc("dbo.ListAll")
.AddParam("limit", 300L)
.AddParam("limitOut", out IOutParam<long> limitOut)
.Exec(r => rows = r.ToList<Model>());
long limitOutValue = limitOut.Value;
ctx.LoadStoredProc("dbo.ReturnBoolean")
.AddParam("boolean_to_return", true)
.ReturnValue(out IOutParam<bool> retParam)
.ExecNonQuery();
bool b = retParam.Value;
ctx.LoadStoredProc("dbo.ListAll")
.AddParam("limit", 1L)
.ExecScalar(out long l);
I'm trying to issue a parameterised SELECT to an Interbase XE database using ADO.NET. The code I'm using is as follows:
using (OdbcConnection odbcConnection = new OdbcConnection(ConfigurationManager.ConnectionStrings["LawbaseTest"].ToString()))
{
odbcConnection.Open();
using (OdbcCommand odbcCommand = new OdbcCommand())
{
odbcCommand.CommandType = CommandType.Text;
odbcCommand.Connection = odbcConnection;
odbcCommand.Parameters.Add(new OdbcParameter(":CaseNumber", 1265));
odbcCommand.CommandText = "select * from cmstub where cm_recnum = :CaseNumber";
using (IDataReader rdrData = odbcCommand.ExecuteReader())
{
Output(rdrData["CM_DESC"]);
}
}
}
I'm getting the following error:
ERROR [42S22] [DataDirect][ODBC InterBase driver][InterBase]Dynamic SQL Error, SQL error code = -206, Column unknown, CASENUMBER
Which suggests to me that the query is not being sent to Interbase in a syntax it recognises as a parameterised query.
This is rather harder than I was expecting. Am I being a ficko? Can you help?
It seems to be the norm that named parameters aren't supported widely, did you try using ? instead, i.e. cm_recnum = :CaseNumber to cm_recnum = ?
I have a table with eighty fields, none to seventy of them can change depending of an update process I have. For example:
if (process.result == 1)
cmd.CommandText = "UPDATE T SET f1=1, f6='S'" ;
else if (Process.result == 2)
cmd.CommandText = string.Format("UPDATE T SET f1=2, f12={0},f70='{1}'", getData(), st);
else if ..... etc.
I can optimize the building process of the UPDATE statement, however I would like to use SQLParameter; is that possible and convenient given the variablity of data to update?
Thanks.
For each if statement you currently are using inline string formats, you could just as well just add the sql params instead.
The formatting of the UPDATE string could be replaced with the selected sql params you require to be updated insted.