I am working in Eclipse and am using 2 Java Files: Admin.java and SemanticSearch.java. Through the the Admin.java I am logging in and checking if the Username and Password are existing in my RDF file. The function of login in Admin.java calls SemanticSearch.java which runs a SPARQL Query. My Query is giving me the answer in Console of Eclipse and even onto another file. Now my job is to give back the answer to Admin.java either by returning the value or by counting rows and sending that value to Admin.java. With this if number of rows is 1 that means the username and password match and I can allow the user to login.
But I am not able to do so. I have tried using count(), Count() as CNT, even tried int res=results.next. But nothing seems to help.
I am pasting the code below:
Admin.java
SemanticSearch semsearch = new SemanticSearch(request.getSession());
semsearch.loadData(REALPATH + RDFDATASOURCEFILE1);
semsearch.searchForUser(response.getOutputStream(),null, userName, password);
In SemanticSearch.java
public void searchForUser(OutputStream out, String xslfile1, String userName, String password) {
String prolog = "PREFIX kb:<"+VUSER.getURI()+">";
System.out.println("Search for user in semantic search.java");
String queryString1 = prolog +"\n" +"SELECT * " +"WHERE {" +"?x kb:Uname ?username. ?x kb:Password ?password. ?x kb:Interest ?interest. " +"FILTER regex(?username, \"" +userName +"\")}";
System.out.println(queryString1);
Query query=QueryFactory.create(queryString1);
QueryExecution qexec = QueryExecutionFactory.create(query, model);
ResultSet results1 = qexec.execSelect(); --> here the two rows are printed
int res=results1.getRowNumber();
System.out.println(results1); -->here answer is 0
ResultSetFormatter.out(results1);
ResultSetFormatter.out(out, results1);
System.out.println(res);
try {
if (xslfile1 != null)
{
out.write(ResultSetFormatter.asXMLString(results1, xslfile1).getBytes("UTF-8"));
System.out.println(results1);
System.out.println(xslfile1);
System.out.println("I am in if");
}
else
{
out.write(ResultSetFormatter.asXMLString(results1).getBytes(
"UTF-8"));
System.out.println("I am in else");
}
} catch (IOException e) {
e.printStackTrace();
}
}
Please Help, I am struggling to get this from a week, Regards, Archana.
In SPARQL 1.1, which may be supported in the triplestore you're using, the syntax is:
SELECT (COUNT(*) AS ?count)
WHERE {
...
}
You should get an integer returned in the ?count column, with the number of results.
Related
I've created a custom Magic command with the intention of generating a spark query programatically. Here's the relevant part of my class that implements the MagicCommandFunctionality:
MagicCommandOutcomeItem execute(MagicCommandExecutionParam magicCommandExecutionParam) {
// get the string that was entered:
String input = magicCommandExecutionParam.command.substring(MAGIC.length())
// use the input to generate a query
String generatedQuery = Interpreter.interpret(input)
MIMEContainer result = Text(generatedQuery);
return new MagicCommandOutput(MagicCommandOutcomeItem.Status.OK, result.getData().toString());
}
This works splendidly. It returns the command that I generated. (As text)
My question is -- how do I coerce the notebook into evaluating that value in the cell? My guess is that a SimpleEvaluationObject and TryResult are involved, but I can't find any examples of their use
Rather than creating the MagicCommandOutput I probably want the Kernel to create one for me. I see that the KernelMagicCommand has an execute method that would do that. Anyone have any ideas?
Okay, I found one way to do it. Here's my solution:
You can ask the current kernelManager for the kernel you're interested in,
then call PythonEntryPoint.evaluate. It seems to do the job!
#Override
MagicCommandOutcomeItem execute(MagicCommandExecutionParam magicCommandExecutionParam) {
String input = magicCommandExecutionParam.command.substring(MAGIC.length() + 1)
// this is the Scala code I want to evaluate:
String codeToExecute = <your code here>
KernelFunctionality kernel = KernelManager.get()
PythonEntryPoint pep = kernel.getPythonEntryPoint(SCALA_KERNEL)
pep.evaluate(codeToExecute)
pep.getShellMsg()
List<Message> messages = new ArrayList<>()
//until there are messages on iopub channel available collect them into response
while (true) {
String iopubMsg = pep.getIopubMsg()
if (iopubMsg == "null") break
try {
Message msg = parseMessage(iopubMsg) //(I didn't show this part)
messages.add(msg)
String commId = (String) msg.getContent().get("comm_id")
if (commId != null) {
kernel.addCommIdManagerMapping(commId, SCALA_KERNEL)
}
} catch (IOException e) {
log.error("There was an error: ${e.getMessage()}")
return new MagicKernelResponse(MagicCommandOutcomeItem.Status.ERROR, messages)
}
}
return new MagicKernelResponse(MagicCommandOutcomeItem.Status.OK, messages)
}
I want to check the username and password with sqlite table,In my case query always returns false...
This is my Query...
public boolean validateUser(String u_name, String p_word){
Cursor c = getReadableDatabase().rawQuery(
"SELECT FNAME,PASSWORD FROM " + TABLE_NAME + " WHERE "
+ fname + "='" + u_name+"'AND "+ password +"='"+ p_word+"'" , null);
if (c!=null)
{
return true;
}
else{
return false;
}
}
Checking whether or not the Cursor is null is basically useless as a valid Cursor will be returned by rawQuery. That is no data to extract will result in an empty Cursor with no rows, whilst if data has been extracted the Cursor will have 1 or more rows.
You should check whether or not the Cursor is empty by using the Cursor getCount() method which will return 0 if there are no rows or the number of rows. Alternately you could use some of the Cursor's move methods which will return true/false depending upon whether the move can be performed. e.g if (c.moveToFirst) { ... //row(s) exist} else { ... //no rows exists }.
You should also close the Cursor before returning. So perhaps use :-
public boolean validateUser(String u_name, String p_word){
Cursor c = getReadableDatabase().rawQuery(
"SELECT FNAME,PASSWORD FROM " + TABLE_NAME + " WHERE "
+ fname + "='" + u_name+"'AND "+ password +"='"+ p_word+"'" , null);
int count = c.getCount(); // get the number of rows
c.close(); // Close the Cursor
return count > 0; // return result (no data found = false, else true)
Many would recommend not using rawQuery but rather the convenience Cursor query method. This could be :-
public boolean validateUser(String u_name, String p_word) {
String[] columns = new String[]{
FNAME,
PASSWORD
};
String whereclause = FNAME + "=? AND " + PASSWORD + "=?";
String[] whereargs = new String[]{
u_name,
p_word
};
Cursor c = this.getWritableDatabase().query(
TABLE_NAME,
columns,
whereclause,
whereargs,
null,null,null
);
int count = c.getCount();
c.close();
return count > 0;
}
Note the above code is in-principle code and hasn't been tested so it may contain typing errors.
The above code assumes that the method is within the Database Helper class (i.e. a subclass of SQLiteOpenHelper).
The assumption has been made that FNAME and PASSWORD are the correct String variables to be used for the column names as opposed to fname and password
Assumptions have been made due to the limited code made available.
I am using Npgsql for postgresql in C++/CLI. So, the problem is, I have a db on my computer, and I am trying to select some of data from it's "movies" table. I already entered some data inside it, so I know that it has some data. But when I try to select some of them, answer to my query is empty. My code is like below:
public: string* SelectData(string* torrent)
{
conn->Open();
String ^ query = "SELECT title, director, actors, genre FROM movies";
Npgsql::NpgsqlCommand ^ command = gcnew NpgsqlCommand(query, conn);
try{
Npgsql::NpgsqlDataReader ^ dr = command->ExecuteReader();
for (int i = 0; i < N_TORRENT; i++)
{
if(dr->Read())
{
string std1 = toStandardString((String^)dr[0]);
string std2 = toStandardString((String^)dr[1]);
string std3 = toStandardString((String^)dr[2]);
string std4 = toStandardString((String^)dr[3]);
torrent[i] = std1 + " " + std2 + " " + std3 + " " + std4;
}
}
return torrent;
}
finally{
conn->Close();
}
}
(For the ones who will look for this question's answer)
Problem solved when I changed my query and look for the "title" column that are not empty. But this is ridiculus, so I beleive the problem was about pgAdmin. Because my insert query was not working either, but I added "rowseffected" variable and it shows the effected row's number and looks like it is working. So the problem is probably about the pgAdmin.
There is a procedure in %Dictionary.ClassDefinitionQuery which lists a class summary; in Java I call it like this:
public void readClasses(final Path dir)
throws SQLException
{
final String call
= "{ call %Dictionary.ClassDefinitionQuery_Summary() }";
try (
final CallableStatement statement = connection.prepareCall(call);
final ResultSet rs = statement.executeQuery();
) {
String className;
int count = 0;
while (rs.next()) {
// Skip if System is not 0
if (rs.getInt(5) != 0)
continue;
className = rs.getString(1);
// Also skip if the name starts with a %
if (className.charAt(0) == '%')
continue;
//System.out.println(className);
count++;
}
System.out.println("read: " + count);
}
}
In namespace SAMPLES this returns 491 rows.
I try and replicate it with a pure SQL query like this:
private void listClasses(final Path dir)
throws SQLException
{
final String query = "select id, super"
+ " from %Dictionary.ClassDefinition"
+ " where System = '0' and name not like '\\%%' escape '\\'";
try (
final PreparedStatement statement
= connection.prepareStatement(query);
final ResultSet rs = statement.executeQuery();
) {
int count = 0;
while (rs.next()) {
//System.out.println(rs.getString(1) + ';' + rs.getString(2));
count++;
}
System.out.println("list: " + count);
}
}
Yet when running the program I get this:
list: 555
read: 491
Why are the results different?
I have looked at the code of %Dictionary.ClassDefinitionQuery but I don't understand why it gives different results... All I know, if I store the names in sets and compare, is that:
nothing is missing from list that is in read;
most, but not all, classes returned by list which are not in read are CSP pages.
But that's it.
How I can I replicate the behaviour of the summary procedure in SQL?
Different is in one property. %Dictionary.ClassDefinitionQuery_Summary shows only classes with Deployed<>2. So, sql must be such.
select id,super from %Dictionary.ClassDefinition where deployed <> 2
But one more things is, why count may be different is, such sql requests may be compilled to temporary class, for example "%sqlcq.SAMPLES.cls22"
I'm attempting to parse SQL using the TSql100Parser provided by microsoft. Right now I'm having a little trouble using it the way it seems to be intended to be used. Also, the lack of documentation doesn't help. (example: http://msdn.microsoft.com/en-us/library/microsoft.data.schema.scriptdom.sql.tsql100parser.aspx )
When I run a simple SELECT statement through the parser it returns a collection of TSqlStatements which contains a SELECT statement.
Trouble is, the TSqlSelect statement doesn't contain attributes such as a WHERE clause, even though the clause is implemented as a class. http://msdn.microsoft.com/en-us/library/microsoft.data.schema.scriptdom.sql.whereclause.aspx
The parser does recognise the WHERE clause as such, looking at the token stream.
So, my question is, am I using the parser correctly? Right now the token stream seems to be the most useful feature of the parser...
My Test project:
public static void Main(string[] args)
{
var parser = new TSql100Parser(false);
IList<ParseError> Errors;
IScriptFragment result = parser.Parse(
new StringReader("Select col from T1 where 1 = 1 group by 1;" +
"select col2 from T2;" +
"select col1 from tbl1 where id in (select id from tbl);"),
out Errors);
var Script = result as TSqlScript;
foreach (var ts in Script.Batches)
{
Console.WriteLine("new batch");
foreach (var st in ts.Statements)
{
IterateStatement(st);
}
}
}
static void IterateStatement(TSqlStatement statement)
{
Console.WriteLine("New Statement");
if (statement is SelectStatement)
{
PrintStatement(sstmnt);
}
}
Yes, you are using the parser correctly.
As Damien_The_Unbeliever points out, within the SelectStatement there is a QueryExpression property which will be a QuerySpecification object for your third select statement (with the WHERE clause).
This represents the 'real' SELECT bit of the query (whereas the outer SelectStatement object you are looking at has just got the 'WITH' clause (for CTEs), 'FOR' clause (for XML), 'ORDER BY' and other bits)
The QuerySpecification object is the object with the FromClauses, WhereClause, GroupByClause etc.
So you can get to your WHERE Clause by using:
((QuerySpecification)((SelectStatement)statement).QueryExpression).WhereClause
which has a SearchCondition property etc. etc.
Quick glance around would indicate that it contains a QueryExpression, which could be a QuerySpecification, which does have the Where clause attached to it.
if someone lands here and wants to know how to get the whole elements of a select statement the following code explain that:
QuerySpecification spec = (QuerySpecification)(((SelectStatement)st).QueryExpression);
StringBuilder sb = new StringBuilder();
sb.AppendLine("Select Elements");
foreach (var elm in spec.SelectElements)
sb.Append(((Identifier)((Column)((SelectColumn)elm).Expression).Identifiers[0]).Value);
sb.AppendLine();
sb.AppendLine("From Elements");
foreach (var elm in spec.FromClauses)
sb.Append(((SchemaObjectTableSource)elm).SchemaObject.BaseIdentifier.Value);
sb.AppendLine();
sb.AppendLine("Where Elements");
BinaryExpression binaryexp = (BinaryExpression)spec.WhereClause.SearchCondition;
sb.Append("operator is " + binaryexp.BinaryExpressionType);
if (binaryexp.FirstExpression is Column)
sb.Append(" First exp is " + ((Identifier)((Column)binaryexp.FirstExpression).Identifiers[0]).Value);
if (binaryexp.SecondExpression is Literal)
sb.Append(" Second exp is " + ((Literal)binaryexp.SecondExpression).Value);
I had to split a SELECT statement into pieces. My goal was to COUNT how many record a query will return. My first solution was to build a sub query such as
SELECT COUNT(*) FROM (select id, name from T where cat='A' order by id) as QUERY
The problem was that in this case the order clause raises the error "The ORDER BY clause is not valid in views, inline functions, derived tables, sub-queries, and common table expressions, unless TOP or FOR XML is also specified"
So I built a parser that split a SELECT statment into fragments using the TSql100Parser class.
using Microsoft.Data.Schema.ScriptDom.Sql;
using Microsoft.Data.Schema.ScriptDom;
using System.IO;
...
public class SelectParser
{
public string Parse(string sqlSelect, out string fields, out string from, out string groupby, out string where, out string having, out string orderby)
{
TSql100Parser parser = new TSql100Parser(false);
TextReader rd = new StringReader(sqlSelect);
IList<ParseError> errors;
var fragments = parser.Parse(rd, out errors);
fields = string.Empty;
from = string.Empty;
groupby = string.Empty;
where = string.Empty;
orderby = string.Empty;
having = string.Empty;
if (errors.Count > 0)
{
var retMessage = string.Empty;
foreach (var error in errors)
{
retMessage += error.Identifier + " - " + error.Message + " - position: " + error.Offset + "; ";
}
return retMessage;
}
try
{
// Extract the query assuming it is a SelectStatement
var query = ((fragments as TSqlScript).Batches[0].Statements[0] as SelectStatement).QueryExpression;
// Constructs the From clause with the optional joins
from = (query as QuerySpecification).FromClauses[0].GetString();
// Extract the where clause
where = (query as QuerySpecification).WhereClause.GetString();
// Get the field list
var fieldList = new List<string>();
foreach (var f in (query as QuerySpecification).SelectElements)
fieldList.Add((f as SelectColumn).GetString());
fields = string.Join(", ", fieldList.ToArray());
// Get The group by clause
groupby = (query as QuerySpecification).GroupByClause.GetString();
// Get the having clause of the query
having = (query as QuerySpecification).HavingClause.GetString();
// Get the order by clause
orderby = ((fragments as TSqlScript).Batches[0].Statements[0] as SelectStatement).OrderByClause.GetString();
}
catch (Exception ex)
{
return ex.ToString();
}
return string.Empty;
}
}
public static class Extension
{
/// <summary>
/// Get a string representing the SQL source fragment
/// </summary>
/// <param name="statement">The SQL Statement to get the string from, can be any derived class</param>
/// <returns>The SQL that represents the object</returns>
public static string GetString(this TSqlFragment statement)
{
string s = string.Empty;
if (statement == null) return string.Empty;
for (int i = statement.FirstTokenIndex; i <= statement.LastTokenIndex; i++)
{
s += statement.ScriptTokenStream[i].Text;
}
return s;
}
}
And to use this class simply:
string fields, from, groupby, where, having, orderby;
SelectParser selectParser = new SelectParser();
var retMessage = selectParser.Parse("SELECT * FROM T where cat='A' Order by Id desc",
out fields, out from, out groupby, out where, out having, out orderby);