I have a matrix called "final_set" which gets created in my R code. Using some of the columns from this final set, I want to create a database table. I'm using the RJDBC package to make this happen.
However, for some reason its not recognizing "final_set" . I know my connection is okay because I've tried out other sql queries using that.
Could anyone help me with this please?
SqlStr = paste("SELECT",
S_Vars, ",", #Global Variable
final_set$pub_idx, ",",
final_set$qty_idx
into dbo.temp1
"from",
final_set,
sep = ""
)
dbSendUpdate(conn,SqlStr)
Error: Error in paste(**): object final_set not found
I think you want your query to be:
SqlStr = paste("SELECT",
S_Vars, #Global Variable
", pub_idx, qty_idx into dbo.temp1 from final_set")
R objects that are not strings shouldn't go in your query as R objects, as their values (not their names) will be coerced to strings.
I'm still a little confused as to your goal. If you're trying to create a table out of an R object, (i.e., final_set is not already a table in your database), then the database won't be able to select columns from final_set. Rather, you should use a function like dbWriteTable. If I'm correct about that, then I think what you're looking for is
dbWriteTable(conn, "temp1", final_set[, c(S_Vars, "pub_idx", "qty_idx")]
Related
I'm using npgsql as a nuget package in visual studio 2017 with visual basic.
Various commands do work very well but an ExecuteScalar allways returns 'nothing' although it should give a result.
The command looks like this:
Dim ser As Integer
Dim find = New NpgsqlCommand("SELECT serial from dbo.foreigncode WHERE code = '#code';", conn)
Dim fcode = New NpgsqlParameter("code", NpgsqlTypes.NpgsqlDbType.Varchar)
find.Parameters.Add(fcode)
find.Prepare()
fcode.Value = "XYZ"
ser = find.ExecuteScalar() ==> nothing
When the command string is copied as a value during debugging and pasted into the query tool of PGADMIN it delivers the correct result. The row is definitely there.
Different Commands executed with ExecuteNonQuery() work well, including ones performing UPDATE statements on the row in question.
When I look into the properties of the parameter fcode immediately before the ExecuteScalar it shows 'fcode.DataTypeName' caused an exception 'System.NotImplementedException'.
If I change my prepared statement to "SELECT #code" and set the value of the parameter to an arbitrary value just this value is returned. There is no access to the table taking place because the table name is not part of the SELECT in this case. If I remove the WHERE CLAUSE in the SELECT and just select one column, I would also expect that something has to be returned. But again it is nothing.
Yes there is a column named serial. It is of type bigint and can not contain NULL.
A Query shows that there is no single row that contains NULL in any column.
Latest findings:
I queried a different table where the search column and the result column happen to have the same datatype. It works, so syntax, passing of parameter, prepare etc. seems to work in principal.
The System.NotImplementedException in the DataTypeName property of the parameter occurs as well but it works anyway.
I rebuilt the index of the table in question. No change.
Still: when I copy/paste the CommandText and execute it in PGAdmin it shows the correct result.
Modifying the Command and using plain text there without parameter and without prepare still does yield nothing. The plain text CommandText was copy/pasted from PGAdmin where it was successfully executed before.
Very strange.
Reverting search column and result column also gives nothing as a result.
Please try these two alternatives and post back your results:
' Alternative 1: fetch the entire row, see what's returned
Dim dr = find.ExecuteReader()
While (dr.Read())
Console.Write("{0}\t{1} \n", dr[0], dr[1])
End While
' Alternative 2: Check if "ExecuteScalar()" returns something other than an int
Dim result = find.ExecuteScalar()
... and (I just noticed Honeyboy Wilson's response!) ...
Fix your syntax:
' Try this first: remove the single quotes around "#code"!
Dim find = New NpgsqlCommand("SELECT serial from dbo.foreigncode WHERE code = #code;", conn)
Update 1
Please try this:
Dim find = New NpgsqlCommand("SELECT * from dbo.foreigncode;", conn)
Q: Does this return anything?
Dim dr = find.ExecuteReader()
While (dr.Read())
Console.Write("{0}\t{1} \n", dr[0], dr[1])
End While
Q: Does this?
Dim result = find.ExecuteScalar()
Q: Do you happen to have a column named "serial"? What is it's data type? Is it non-null for the row(s) with 'XYZ'?
Please update your original post with this information.
Update 2
You seem to be doing ":everything right":
You've confirmed that you can connect,
You've confirmed that non-query updates to the same table work (with npgsql),
You've confirmed that the SQL queries themselves are valid (by copying/pasting the same SQL into PGAdmin and getting valid results).
As Shay Rojansky said, "System.NotImplementedException in the DataTypeName property" is a known issue stepping through the debugger. It has nothing to do with your problem: https://github.com/npgsql/npgsql/issues/2520
SUGGESTIONS (I'm grasping at straws)::
Double-check "permissions" on your database and your table.
Consider installing a different version of npgsql.
Be sure your code is detecting any/all error returns and exceptions (it sounds like you're probably already doing this, but it never hurts to ask)
... and ...
Enable verbose logging, both client- and server-side:
https://www.npgsql.org/doc/logging.html
https://www.postgresql.org/docs/9.0/runtime-config-logging.html
... Finally ...
Q: Can you make ANY query, from ANY table, using ANY query method (ExecuteReader(), ExecuteScalar(), ... ANYTHING) from your npgsql/.Net client AT ALL?
I finally found it. It's often the small things that can have a big impact.
When the value was assigned to the parameter a substring index was incorect.
Now it works perfectly.
Thanks to everybody who spent his time on this.
I am working with Unidata, and ADO.NET using the U2 .NET Provider. This may be a shot in the dark as there are not many resources for Unidata and .NET these days.
Currently I can only return a single MV record 153926þIþ and parse it using MV_To_DataTable. I'd like to return multiple records like 153926þIþÿ153926þIþÿ. Is there any built in mechanism for doing this? I fear I will have to write the extension to best accomodate me.
I retrieve a single record in a unidata subroutine this way:
SUBROUTINE GETITEMS(results)
EXECUTESQL "SELECT ID, STATUS, DESC FROM ITEMS TO GETITEM_LIST;"
DONE = 0
RECCNT = 0
LOOP
RECCNT += 1
READNEXTTUPLE REC FROM "GETITEM_LIST" ELSE DONE = 1
results := REC
IF RECCNT EQ 1 THEN EXIT
UNTIL DONE
REPEAT
results
CLEARSQL
RETURN
Simple subroutine that returns one record without any record marks. This works when I use the U2Parameter method called MV_To_DataTable to parse it into an existing datatable.
However when I change the subroutine line:
results:= REC to results:= REC : #RM to append the record marks and remove the limit of 1, the MV_To_DataTable no longer is able to parse it correctly. In fact it will throw System.IndexOutOfRangeException: Cannot find column 3.
VB.NET Code:
' ... Open database connection called U2Connection ...
Dim cmd = U2Connection.CreateCommand
cmd.CommandText = "CALL GETITEMS(?)"
cmd.CommandType = CommandType.StoredProcedure
cmd.Parameters.Clear()
cmd.Parameters.Add(New U2Parameter("#arg1", "") With {.Direction = ParameterDirection.InputOutput})
cmd.ExecuteNonQuery()
Dim tb As New DataTable
tb.Columns.Add("ID")
tb.Columns.Add("STATUS")
tb.Columns.Add("DESC")
cmd.Parameters.Item(0).MV_To_DataTable(tb) ' Error happens here
' System.IndexOutOfRangeException: Cannot find column 3.
It appears the method does not separate records. I could be interpretting this incorrectly.
*****UPDATE 2/9/2019
I went ahead and wrote my own extension method to support my return format with the record markers. It populates a datatable with records allowing me to continue as I normally would.
You are kind of straddling the Multivalue/System.Data divide here. If you have not already done so, I would suggest looking into the U2 Toolkit for .NET, which I believe is generally readily available if you are current on maintenance. It comes with some samples of how to do things like this in C# and VB as well some Entity Framework stuff.
But as to what is going on here, You are trying to put a U2Type.DynArray into a System.DataTable is kind of tricky as the DynArray is a Record state, which could contain multiple rows from multiple tables within a DataSet. As #RM is the terminator for a record so it turns DynArray into DynArray[] and you can't have that as a parameter as such.
To fix this with the minimum refactoring, you can still use MV_To_DataTable, but note that it is expecting your data to be tabular and in in a single record. These example assume a newline is an Attribute mark (#FM/#AM)
Here is the contents of what you are returning
Row1Column1
Row1Column2
Row1Column3:#RM
Row2Column1
Row2Column2
Row2Column3:#RM
Row13olumn1
Row13olumn2
Row13olumn3:#RM
And here is what MV_To_DataTable expects
Row1Column1:#VM:Row1Column2:#VM:Row1Column3
Row2Column1:#VM:Row2Column2:#VM:Row2Column3
Row3Column1:#VM:Row3Column2:#VM:Row3Column3
If you adjust your U2 sub to output that, it should work.
Additionally, you could try using your SQL command directly for .net, but that becomes perilous for other reasons depending on your data.
Good Luck!
I never asked any questions on stackoverflow but it already brought me tons of answers !
But this time, after some extended research, I have to ask it myself.
I'm using VB.Net with Sqlite and my query doesn't return any value when I execute it with parameters. I guess this has something to do with the fact SituationString contains commas but I really can't figure it out.
Here's is my code :
dim ChildCtx as Integer
dim SituationString as String
SituationString="968,970,978,979,980,981,995,1022,1099,1119"
With DataBase
.SQL_CMD.Parameters.Clear()
.SQL_CMD.CommandText = "SELECT SERVCTX_NO FROM SERVCTX WHERE SERVCTX_NO IN (#situationstring) AND MASTER = '1'"
.SQL_CMD.Parameters.Add("#situationstring", SqlDbType.VarChar, 255).Value = SituationString
ChildCtx = .SQL_CMD.ExecuteScalar
.SQL_CMD.Parameters.Clear()
End with
Connection is open and query works out fine if I write the whole query into one string.
Thanks,
You are mixing two techincs: merging constant data into SQL command and using parameters to pass data.
I suppose SituationString is a list of integer you expect for SERVCTX_NO.
So, you must merge it into statement:
.SQL_CMD.CommandText = "SELECT SERVCTX_NO FROM SERVCTX WHERE SERVCTX_NO IN ("+SituationString+") AND MASTER = '1'"
ChildCtx = .SQL_CMD.ExecuteScalar
Using parameters, as you did, SERVCTX_NO would be expected to be a string with 968,970,978,979,980,981,995,1022,1099,1119 exact content!
i'm trying to execute following line of code with my servelet in netbeans:
ResultSet rs = stmnt.executeQuery("select * from ZEE.WORDCOUNT where WORD =" + searchTxt);
where searchTxt is String variable.
but it says "Column 'zeeshan' is either not in any table in the FROM list or appears within a join specification and is outside the scope of the join . . . . ".
it really works fine, if i provide the hardcoded value instead of variable, as:
ResultSet rs = stmnt.executeQuery("select * from ZEE.WORDCOUNT where WORD= 'zeeshan'");
i'm not getting, what i'm missing?
You are missing the single quotes around the sql string you are constructing. So this should work:
ResultSet rs = stmnt.executeQuery("select * from ZEE.WORDCOUNT where WORD ='" + searchTxt+"'");
Please note that constructing SQL statements in this way is really dangerous, because it opens your application up for SQL injection attacks. Use bind parameters instead.
This will also allow better caching of parsed statements on many rdbms's.
Having a bit of trouble having not long started with Entity Framework.
I have two tables which have a 0 to 1 relationship. When I select a row from the main table (staff) it's fine unless I select a row that has no joining record in the second table (status). If I do this, then it throws up 'Object reference not set to instance of an object' when it's trying to access the proprty of the second table:
If Not cls.STATUS_DESC.STAFF_INFO Is DBNull.Value Then
lblStatusDescription.Text = cls.STATUS_DESC.STAFF_INFO
End If
The LINQ I use to get the record is:
Dim account As STAFF =
(From a In sa.STAFFs
Where a.STAFF_NO = staffno
Select a).FirstOrDefault
There is no direct reference to the sub table in the statement, however the join is defined in the database diagram which allows me to reference the properties.
I'm certain it's a very basic issue, but like I said I've only just started using it!
I'm not sure if I can interpret your code correctly but I think it has to do with the Lazy Loading feature of Entity Framework. You must explicitly include the reference to load it into memory. You can to this by using the Include() method as below. I assume that STATUS_DESC is the name of the navigation property. Replace it with the actual one if I'm wrong:
Dim account As STAFF =
(From a In sa.STAFFs Where a.STAFF_NO = staffno Select a) _
.Include("STATUS_DESC") _
.FirstOrDefault
Got around it by adding:
If Not cls.STATUS_DESC Is Nothing Then
end if
to the property call, which seems fairly obvious now I think about it. Is this the most efficient way though, I would have thought that EF would have been able to handle a simple left join.