I am trying to select a column which type is UUID:
const std::wstring Select = L"SELECT OptionID FROM OptionsSet WHERE OptionID = ?";
// Create query object
query->addUUID(some_option_id);
query->execute();
After execution I am getting
Error number SqlState=42000 NativeError=102 ErrorMsg=[Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Incorrect syntax near '#P1'.
I suppose '?' is being replaced with UUID like this:
OptioID = 70fc92c2-6fd9-4727-8b29-f55b8d6fb07c
but instead I guess it should have been
OptioID = '70fc92c2-6fd9-4727-8b29-f55b8d6fb07c'
I have tried to add that punctuation mark: L"SELECT OptionID FROM OptionsSet WHERE OptionID = '?'";, but it didn't help.
Well, I found the issue: I forgot to put semicolon at the end of the query. So, it should be:
const std::wstring Select = L"SELECT OptionID FROM OptionsSet WHERE OptionID = ?;";
I have been picking my brain for a while trying to figure this one out.
The problem I am having is that the function I am using in Oracle returns a BLOB. It's a list of items that are concatenated together using ||.
From the research I have done,
In the QSQLQuery docs it says "Stored procedures that uses the return statement to return values, or return multiple result sets, are not fully supported. For specific details see SQL Database Drivers." - which leads me to believe I may need to switch to a different codebase if Qt cannot handle it yet.
The documentation for the QOCI driver mentions this "Binary Large Objects (BLOBs) can be read and written, but be aware that this process may require a lot of memory. You should use a forward only query to select LOB fields (see QSqlQuery::setForwardOnly())."
I did set
query.setForwardOnly(true);
Before I prepared or executed the statement.
However, I still get this error
QSqlError("6502", "Unable to execute statement", "ORA-06502: PL/SQL: numeric or value error: character string buffer too small\nORA-06512: at line 55\n")
I had to scrub the code a bit, I hope this is still helpful to give context to what i'm trying to accomplish
temp_clob clob;
name varchar2(183) := ?;
start varchar2(16) := ?;
end varchar2(16) := ?;
count integer := ?;
return_val named_redacted_table_object; -- Sorry had to remove this, it's a table with more Date, Varchar, etc
begin
dbms_lob.createtemporary(temp_clob, true);
return_val := package_name.function_name (
set_name => name,
start_time => to_date(start, 'yyyy-mm-dd hh24:mi'),
end_time => to_date(end, 'yyyy-mm-dd hh24:mi'),
max_count => count);
-- In here was a loop that would break apart the removed table object and make it into strings along the following lines
-- '' || return_val(i).name || return_val(i).value || etc
-- and would store these into the CLOB / temp_clob
? := temp_clob;
end;
I could not get something as simple as this to work
begin
? := 'test123';
end;
With the assumption I could at least read this string in Qt.
Here is my code for Qt
QString name = "test";
QSqlQuery query(db);
query.setForwardOnly(true);
query.prepare(sql);
QString test_sql_text = ui->comboBox_test_text->currentText();
qDebug() << name;
query.bindValue(0, name);
query.bindValue(1, "2003-03-14 00:00");
query.bindValue(2, "2005-03-14 23:00");
query.bindValue(3, 2);
query.bindValue(4, QString(""), QSql::Out);
bool query_executed_ok = query.exec();
qDebug() << "did it execute?" << query_executed_ok;
// qDebug() << query.executedQuery();
qDebug() << query.boundValues();
qDebug() << query.lastError();
QSqlRecord rec = query.record();
qDebug() << rec;
int record_count = rec.count();
qDebug() << "Records: " << record_count;
while (query.next()) {
for(int i=0;i<record_count;i++) {
qDebug() << query.isValid() << " - " << rec.fieldName(i) << " " << query.value(i).toString();
}
}
The error posted appears to be from within the Oracle code; ORA.... You have stripped so much it's hard to see what is actually happening, especially the are where the error apparently occurred. But perhaps using Oracle supplied code that is specifically designed to handle CLOBs. Instead of
'' || return_val(i).name ...
Try
dbms_lob.append(temp_clob, to_clob(return_val(i).name))
begin
? := 'test123';
end;
Bind variables are used to assign values to variables. You define your variable in your pl/sql code and assign a value to it at runtime by using a bind variable. In that case pl/sql code will compile correctly.
In your code the bind variable is used to replace the pl/sql variable, not the value, which will fail. Your pl/sql block cannot be compiled because it cannot resolve the "?".
A valid use of bind variables would be
BEGIN
l_xyz := ?;
END;
where you assign the value test123 at runtime.
It took some fiddling, and I realize I gave fairly cryptic code. So thank you to belayer and Koen for taking a shot at my mess.
What I was able to determine and get working for anyone else running into this:
Let me start off by saying I am not sure if this is a bug, or if i'm doing something in a way that was not intended by the designers of QSqlQuery (The class for handling SQL calls).
The call would work in SQL developer and I would see the intended CLOB with all characters. I was unable to get DBMS_Output to work, however, I saw this post saying to reserve space on the string before binding it to the query.
It solves my issue and shows the result in the debug window. However, it presents a new problem. What if the string becomes larger than my hard coded reserve value?
Here's the updated code for that
query.prepare(sql);
QString name= ui->comboBox_name->currentText();
qDebug() << project;
query.bindValue(":name", project);
query.bindValue(":start_date", "2005-03-14 00:00");
query.bindValue(":end_date", "2006-03-14 23:00");
query.bindValue(":max_count", 3);
QString testStr ="*****";
//testStr.truncate(0); //Maybe this works too?
testStr.reserve( 1000000 ); // This did it for sure
qDebug() << testStr.capacity();
query.bindValue(":result_clob", testStr, QSql::Out);
bool query_executed_ok = query.exec();
qDebug() << "did it execute?" << query_executed_ok;
if (query_executed_ok) {
testStr = query.boundValue(":result_clob").toString();
qDebug() << testStr;
} else {
qDebug() << "string is empty";
}
I got the idea to do this, from THIS post.
Imagine you have a table in a CSV file with this kind of layout:
name,property1 [unit1],property2 [unit2]
name1,4.5,2.3
name2,3.2,7.4
name3,5.5,6.1
I need to convert each row to this kind of JSON structure (ie, for row 1):
{
"name1": [
{
"properties": [
{
"property_1": "_value_",
"unit": "unit1"
},
{
"property_2": "_value_",
"unit": "unit2"
}
]
}
]
}
On top of it all, I have to explain that I am using Qt 4.7 and can't update; also, I can't install Qxt so I'm relying on qt-json for the JSON parsing/encoding. More, the CSV file is not created/maintained by me, so I can't really change it either.
So with all of this, I realised I need a few things, so this is a kind of multiple question:
how should I write the RegEx to read the unit in each column's header? Please note that the unit is enclosed in rect-parenthesis.
imagine I extract both the header row and the other rows into a QList<QString>, separating each column as a string. How can I manage to sync all the bits of data in order to create the JSON structure I need on a QString? (I think I need it in a QString so I can dump each row in a different file, but I'm open to other options as well)
Just one final note - I also need to this to be somewhat scalable. The CSV files on which this will be apllied are very heterogenous in column count: some have 8 columns, others have 20.
I know it is not a good practice to post "multiquestions", but the thing is I'm feeling too overwhelmed with all of this, and because I have virtually no experience with Qt, I can't even define a plan to attack this. Hope someone can share some pointers. Thanks!
EDIT
So, I've been thinking a little more about this and I don't actually know if this is a good idea/feasible but here is what I thought of:
when going through the header row, I would check if each column string had a hit for the RegEx. If so, I would store the column index and the unit string in a list;
then, when going through the other rows, in order to parse them into JSON, I would check in each column if it matched the index in the previous list, and if so, I would then add the unit to the map (as qt-json docs explains)
Does this make any sense? Can anyone mock up a skeleton I can work on for this?
EDIT2
I've managed to get a few things working so far, but still not working as it should. Right now I have managed to read properly from the CSV file, but the output isn't coming out right. Can anyone share some insight?
NOTE: the processLineFromCSV function returns a QStringList obtained like so: QStringList cells = line.split(separator_char);
NOTE2: the RegEx was obtained from this answer.
NOTE3: Check below for the type of output I'm getting. Right now I think the problem relates more to the usage of the qt-json lib than actually the rest of the code, but any help is welcome! :)
The code so far:
QFile file(csvfile);
if (file.open(QIODevice::ReadOnly | QIODevice::Text))
{
bool first = true;
QVariantMap map;
QVariantMap propertyMap;
QList<QVariant> generalList, propertiesList;
while (!file.atEnd())
{
QString line = file.readLine();
if(first == true){
headerList = processLineFromCSV(line, separator_char);
first = false;
}else{
QStringList cellList = processLineFromCSV(line, separator_char);
int i=0;
for(i; i<cellList.size(); i++)
{
// check the header cell for "[unit]" string
// returns -1 if does not have the string
// if it has the string, it's stored in capturedUnits[1]
int test = exp.indexIn(headerList.at(i));
// store the captured units in a QStringList
QStringList capturedUnits = exp.capturedTexts();
if(test==-1){ // if header does not have a captured unit - general column
QString name = headerList.at(i);
QString sanitizeName= name.remove(exp.capturedTexts().at(0), Qt::CaseSensitive);
map[sanitizeName] = cellList.at(i);
}
else{ // if header string has a captured unit - property column
QString propertyName = headerList.at(i); // extract string in header
QString sanitizedPropertyName = propertyName.remove(exp); //remove the unit regex from the string
sanitizedPropertyName.remove(QChar('\n'), Qt::CaseSensitive); // clear newlines
if(sanitizedPropertyName.startsWith('"') && sanitizedPropertyName.endsWith('"'))
{
sanitizedPropertyName.remove(0,1);
sanitizedPropertyName.remove(sanitizedPropertyName.length(),1);
}
QString value =cellList.at(i); // extract string in value
QString sanitizedValue = value.remove(QChar('\n'), Qt::CaseSensitive); // clear newlines
if(sanitizedValue.startsWith('"') && sanitizedValue.endsWith('"'))
{
sanitizedValue.remove(0,1);
sanitizedValue.remove(sanitizedValue.length(),1);
}
propertyMap[sanitizedPropertyName]= sanitizedValue; // map the property: value pair
propertyMap["unit"] = capturedUnits.at(1); // map the unit: [unit] value pair
QByteArray general = QtJson::serialize(map); // serialize the pair for general column
QByteArray properties = QtJson::serialize(propertyMap); // serialize the pair for property column
QVariant genVar(general);
QVariant propVar(properties);
generalList.append(genVar);
propertiesList.append(propVar);
}
}
}}
QByteArray finalGeneral = QtJson::serialize(generalList);
QByteArray finalProperties = QtJson::serialize(propertiesList);
qDebug() << finalGeneral;
qDebug() << finalProperties;
file.close();
}
The ouput:
"[
"{ \"name\" : \"name1\" }",
"{ \"name\" : \"name1\" }",
"{ \"name\" : \"name2\" }",
"{ \"name\" : \"name2\" }",
"{ \"name\" : \"name3\" }",
"{ \"name\" : \"name3\" }"
]"
"[
"{ \"property1 \" : \"4.5\", \"unit\" : \"unit1\" }",
"{ \"property1 \" : \"4.5\", \"property2 \" : \"2.3\", \"unit\" : \"unit2\" }",
"{ \"property1 \" : \"3.2\", \"property2 \" : \"2.3\", \"unit\" : \"unit1\" }",
"{ \"property1 \" : \"3.2\", \"property2 \" : \"7.4\", \"unit\" : \"unit2\" }",
"{ \"property1 \" : \"5.5\", \"property2 \" : \"7.4\", \"unit\" : \"unit1\" }",
"{ \"property1 \" : \"5.5\", \"property2 \" : \"6.1\", \"unit\" : \"unit2\" }"
]"
This should be a good start for you:
QString csv = "name,property1 [unit1],property2 [unit2],property3 [unit3]\n"
"name1,4.5,2.3\n"
"name2,3.2,7.4\n"
"name3,5.5,6.1,4.3\n";
QStringList csvRows = csv.split('\n', QString::SkipEmptyParts);
QStringList csvHeader = csvRows.takeFirst().split(',');
csvHeader.removeFirst();
foreach(QString row, csvRows) {
QStringList values = row.split(',');
QString rowName = values.takeFirst();
QVariantList properties;
for(int i = 0; i < values.size(); i++) {
QString value = values[i];
QStringList propParts = csvHeader[i].split(' ');
QString propName = propParts[0];
QString propType = propParts[1].mid(1, propParts[1].size() - 2);
QVariantMap property;
property[propName] = value;
property["unit"] = propType;
properties.append(property);
}
QVariantMap propertyObj;
propertyObj["properties"] = properties;
QVariantList propList;
propList.append(propertyObj);
QVariantMap root;
root[rowName] = propList;
QByteArray json = QtJson::serialize(root);
qDebug() << json;
// Now you can save json to a file
}
Joum.
Just seen your response to my comment. I don't have much experience with QT either, but a quick outline....
Extract the data one line at a time, and 'split' it into an array. If you are using CSV you need to be sure that there are no data points that have a comma in them, or the split will result in a real mess. Check with whoever extracted the data if they can use another 'less common' separator (eg a '|' is good). if you data is all numeric that is great, but be wary of locations that use the comma as a decimal separator :(
I hope that you have 1 'table' per file, if not you need to be able to 'identify' when a new table starts somehow, this could be interesting / fun - depends on your outlook ;).
At the end you will have a collection of 'string arrays' (a table of some sort) hopefully the first is your header info. If you have mutliple tables, you will deal with them one at a time
You should now be able to 'output' each table in good JSON format.
Getting your 'units' from the header rows: If you know in advance where they are located (ie the index in the array) you can plan for extracting the info (using a regex if you wish) in the correct index locations.
Last point.
If your csv file is very long (hundreds of lines), just grab the first few into a new test file for quicker debuging, then once you are happy, enlarge it a bit and check the output format... then again once you are happy that there are no other bugs... for the whole file
Likewise if you have multiple tables in your file, start with the first one only, then add the first part of a second... test.... add a third.... test etc etc etc until you are happy
David.
A possibly better solution, after reading your comment about wanting some form of 'synchronisation'.
NOTE: this may seem a little more complex, but I think it would be a more flexible solution in the end. Also does this data not exist in a DB somewhere (who gave it to you?), can they give you direct read access to the underlying DB and tables? if so, you can jump straight to the 'output each table to JSON' step.
using an embeded DB (ie SQLite).
Extract the first 'header' row, and create a table in your DB that follows the info there (you should be able to add info regarding units to the 'metadata' ie a description). If all your files are the same you could even import all the data into the same single table, or auto create a new table (assuming the same format) for each new file using the same create table statement.
I'm sure there is a 'csvimport' in SQLite (I haven't checked the docs yet, and haven't done this in a while) or someone has written a library that will do this.
Output each table to JSON format, again I'm sure someone has written a library for this.
Using the answer by ExplodingRat this is the final code: (without file creation at the end)
QString csvfile = ui->lineEditCSVfile->text();
QString separator_char = ui->lineEditSeparator->text();
QRegExp exp("\\[([^\\]]+)\\]");
QFile file(csvfile);
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return;
QString csv = file.readAll();
QStringList csvRows = csv.split('\n', QString::SkipEmptyParts);
QStringList csvHeader = csvRows.takeFirst().split(separator_char);
csvHeader.removeFirst();
foreach(QString row, csvRows) {
QStringList values = row.split(separator_char);
QString rowName = values.takeFirst();
QVariantList general;
QVariantList properties;
for(int i = 0; i < values.size(); i++) {
QString value = values[i];
int test = exp.indexIn(csvHeader[i]);
//qDebug() << test;
//qDebug() << csvHeader;
QStringList capturedUnits = exp.capturedTexts();
QString propName = csvHeader[i];
if(test==-1){
//QString propName = csvHeader[i].remove(exp);
//qDebug() <<"property name" << propName;
QVariantMap property;
property[propName] = value;
general.append(property);
}else{
propName.remove(exp);
//QStringList propParts = csvHeader[i].split(' ');
//QString propName = csvHeader[i].remove(exp);
QString propType = capturedUnits[1];
QVariantMap property;
property[propName] = value;
property["unit"] = propType;
properties.append(property);
}
}
QVariantMap propertyObj;
propertyObj["properties"] = properties;
QVariantList propList;
propList.append(propertyObj);
QVariantMap generalObj;
generalObj["general"] = general;
QVariantList generalList;
generalList.append(generalObj);
QVariantList fullList;
fullList.append(generalObj);
fullList.append(propertyObj);
QVariantMap root;
root[rowName] = fullList;
QByteArray json = QtJson::serialize(root);
json.prepend('[');
json.append(']');
qDebug() << json;
// Now you can save json to a file
I tried to create a SQLite database with Qt and and I did!! I called my db "prova_db" and it contains the following table:
marker_db
id site (columns)
0 www.google.it
1 www.youtube.it
2 www.facebook.it
Then, I tried to query my prova_db. Here is code:
int main () {
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("prova_db");
if (!db.open()) { printf("DB doesn't exist\n");}
else {
QSqlQuery query1;
query1.exec( "SELECT site FROM marker_db WHERE id = 1");
int i = query1.numRowsAffected();
printf("result row: %d\n", i);
while(query1.next()){
QString str = query1.value(0).toString();
printf("result: %s\n", str);
}
}
db.close();
return 0;
}
The result is:
result row : 0
result : (strange char)
instead the result should be:
result row: 1
result : www.youtube.it
where am I doing wrong??
Thank you!
I think you have the wrong expectation: the result of numRowsAffected() tells you how many rows have been altered by the query. Your query does not alter anything, so the result should be either 0 or undefined. Thus, you shouldn't expect the first output to be risultato riga: 1. Use the size() method instead to find out how many rows have matched your SELECT query.
The second problem is that you are passing a QString object to printf(), which expects a pointer to a null-terminated array of char values instead (when you use the %s format specifier). You need to convert the QString object into a pointer to a C array of characters.
I'd need some advice how to handle transactions with Informix CSDK and OIC++.
conn is a open connection object. Select works find. The database here is setup with logging — as I found out while update stmt on its own does nothing.
Here's what I tried:
conn.SetTransaction( ITConnection::BEGIN );
qtext = "UPDATE transit_kunde_s SET erledigt='Y' WHERE transitkunde='"+ts+"'";
cout << qtext << endl;
code = query_up.ExecForStatus(qtext.c_str());
cout << "code " << code << endl;
conn.SetTransaction( ITConnection::COMMIT );
okay once again I answer myself...
from Informix C++ DocNotes
Operations can now be performed on large objects within a fetched row even though the connection is still checked out (locked). A connection is checked out after the ITQuery::ExecForIteration() method returns multiple rows in the result set. It remains checked out until either the last row in the result set has been fetched with ITQuery::NextRow() or the query processing has been terminated by calling ITQuery::Finish(). While a connection is checked out, no other query can be executed on that connection.
So as I am in the while loop of one query result iteration I need for another update query a new connection
// already have 2 connection objects: conn, conn2
ITQuery query(conn);
ITQuery query_up(conn2);
string qtext;
qtext = "SELECT * FROM transit_kunde_s WHERE erledigt='N' ORDER BY transitkunde";
okay = query.ExecForIteration(qtext.c_str());
while (row = query.NextRow()) {
// do stuff
// NOW WANT TO DO ANOTHER QUERY? --> NEED ANOTHER CONNECTION!!
ok_ta = conn2.SetTransaction( ITConnection::BEGIN);
qtext = "UPDATE transit_kunde_s SET erledigt='Y' WHERE transitkunde='"+ts+"'";
code = query_up.ExecForStatus(qtext.c_str());
ok_ta = conn2.SetTransaction( ITConnection::COMMIT );
}
// we see later the 1st query to be finished here
query.Finish();