WP8 SQlite Select Query - sql

I have following code.
string DB_PATH = Path.Combine(ApplicationData.Current.LocalFolder.Path, "Questions.sqlite");
SQLiteConnection dbConn = new SQLiteConnection(DB_PATH);
dbConn.CreateTable<QuestionModel>();
// Some code which insert the records in database from webservices.
List<QuestionModel> questionsList = dbConn.Table<QuestionModel>().ToList();
System.Diagnostics.Debug.WriteLine("List Count " + dbConn.Table<QuestionModel>().ToList().Count);
The List Count gives me 0 always. But When I use WP POWER TOOLS and get the Questions.sqlite file from emulator. It gives me records in SQLite table.
I also check the query in http://sqlitestudio.pl/ on the same Questions.sqlite but that gives me records as it should.
I tried other way to get the records as following code but none them were working.
String query = "Select * from QuestionModel;";
questionsList = dbConn.Query<QuestionModel>(query);
System.Diagnostics.Debug.WriteLine("List Count " + questionsList.Count);

With your analysis seems like only the row List<QuestionModel> questionsList = dbConn.Table<QuestionModel>().ToList(); is not working.
I helped someone in SQLiteDB on WP8 a couple of days ago, here is his question : SQLite WP8 StackOverflow
If you compare his code with your code, you are missing the Model bindind :
db.GetTableInfo("QuestionModel");
And
db.Table<QuestionModel>().ToList<QuestionModel>();
Not important but use your list variable to get count in debug write to not retrieve twice the list questionsList.Count
Hope it helps.

Related

npgsql executescalar() allways returns nothing

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.

JPA native query gives incorrect output

I know this may sound silly but I've been stuck on this problem for too long!
I'm querying a PostgreSQL repository through JPA using native SQL queries. One of my queries looks like this:
#Query(value = "select * from gs where ?1 = ?2", nativeQuery = true)
public List<GsJsonStore> matchJson(String term, String value);
I'm testing the function using :
List<GsJsonStore> list = repo.matchJson("subject", "'Sub'");
The list is empty on running the query, however when I run the same query through PSQL command line using:
select * from gs where subject = 'Sub';
I get the correct output, records contatining the key-value pair are returned.
Where am I making the mistake?
You can't use parameter for column name. Your query resolves to
select * from gs where 'subject' = '''Sub'''
EDIT: just saw #pozs already posted the same in comment

Using a Join query with ignited datatables trying to get a where with two conditions

I am attempting to pull data from mysql database using codeigniter and ignited datatables. I have no troubles pulling the join query with a single where clause, but when I try to add a WHERE x OR y, I can't seem to get it working. Here is the basic code that works fine:
$table = 'test_base';
$table2 = 'lab';
$this->datatables->select('test_base.idlab');
$this->datatables->from($table);
$this->datatables->join($table2, 'test_base.idlab = lab.idlab');
$this->datatables->where('lab.idaccount',$idaccount);
If I wanted to put multiple conditions in the query, I see from the manual that I can put multiple conditions in an array, but this seems to only do an AND, not an OR statement.
I then see that I may be able to create my own sql query using the following:
$this->datatables->where('column != "string"');
So, I tried this:
$this->datatables->where("`lab`.`idaccount`= $idaccount OR `lab`.`idlab` = 0");
SELECT `test_base`.`idlab`
FROM (`test_base`)
JOIN `lab` ON `test_base`.`idlab` = `lab`.`idlab`
WHERE `lab`.`idaccount`=` 124 OR `lab`.`idlab` = 0
ORDER BY `idtest` asc
The issue is that there is an extra (`) in the WHERE `lab`.`idaccount` = `<-here and I'm not sure how to get rid of it.
As #Ehecatl suggests, I got it working by entering the full query into the (). There were no examples on the CodeIgniter website or anywhere else I could find. Still new to CodeIgniter so maybe this will also help others.
Resolution is to put the query string in the $this->datatables->where(); and removing all the single quotes.
$this->datatables->where("lab.idaccount = $idaccount OR lab.idlab = 0");

VB.Net Sqlite - Parameterized query not working

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!

NHibernate SQL query issue with string parameter

I got a problem with this code:
string sql = "select distinct ruoli.c_tip_usr"
+ " from vneczx_ute_app_trn ruoli"
+ " join vnecyd_ent_prf ind"
+ " on ruoli.c_ent = ind.c_ent"
+ " where ruoli.c_app = :appCode"
+ " and ruoli.c_ute_mat = :matricola"
+ " and ind.t_des_ent = :indirizzo";
var ruoli = session.CreateSQLQuery(sql)
.SetString("appCode", Config.Configurator.Istance.ApplicationCode)
.SetString("matricola", user.Matricola)
.SetString("indirizzo", indirizzoCasella)
.List<string>();
This code is correctly executed, the query logged is correct, and the parameter passed correctly evaluated... but it doesn't return any result at all.
Copying the query from the debug console and executing it directly in an Oracle client application (SQL Developer), it gets 2 results (the results I expect to be right).
I found out that the problem is in the last parameter indirizzo, and should depend on the fact that it contains a special char # (indirizzo is an email address).
So I ended up using this solution:
string sql = "select distinct ruoli.c_tip_usr"
+ " from vneczx_ute_app_trn ruoli"
+ " join vnecyd_ent_prf ind"
+ " on ruoli.c_ent = ind.c_ent"
+ " where ruoli.c_app = :appCode"
+ " and ruoli.c_ute_mat = :matricola"
+ " and ind.t_des_ent = '" + indirizzoCasella + "'";
var ruoli = session.CreateSQLQuery(sql)
.SetString("appCode", Config.Configurator.Istance.ApplicationCode)
.SetString("matricola", user.Matricola)
.List<string>();
But it gives me thrills! Aren't the parameters in a query supposed to handle specifically this situation, and thus handle themselves situations with special char, and so on?
Why here a string concatenation works better that a parametric query?
Isn't there a way to force the NHibernate engine to escape some special char?
Update:
I found out how to solve this particular issue: usign the trim command on the field who raise the problem, the problem disappears.
So last line of my sql string now is:
+ " and trim(ind.t_des_ent) = :indirizzo";
I can't understand why it solves the problem thought. Not the field, nor the variable contains empty chars and copying th query on SQL Developer works in both way.
So we have some luck soving the problem, but we have no idea why now it works?
Any thoughts?
even I was facing the same issue, but your hint using TRIM for column saved my day. Since I was looking for a long time, but not able to figure it out.
Along with that, I was able solve my issue by doing the below changes as well:
We were using CHAR datatype some of the columns which used in the query where clause. This was causing the issue to fetch the data from NHibernate. We changed the data type of that column from CHAR to VARCHAR2 and even updated the data with actual size and removed the TRIM from Where clause, the TRICK WORKED!!!! :)
So, any one face this kind of issue, first check whether you are having any column with CHAR and then change to VARCHAR2.
But one more thing you have to remember is: if you are running your application from ASP.Net Development Server, close it and re-run your application. Since if the opening Asp.Net Development Server and if you make any changes to datatype that will NOT be refreshed in your oracle connection. So, better you close the ASP.Net Development server and then re run the application.
Hope my points will help somebody in future!!
Regards,
Sree Harshavardhana
You are not using parameters in a SQL query if you want SQL parameters use a SQL stored proc