I am writing a installer for windows using NSIS. The installer gets few properties during installation and it needs to update one of the table in sqlite database that is bundled with the installer. Is it possible to update sqlite database file using NSIS?
It does not seem like there are any SQLite plugins.
Your options are:
Write your own plugin (included for completeness, but almost certainly not a real option)
Use nsExec to run SQLite commands via the command line interface. See discussion on NSIS forums
Write a small app to include with your installer that makes the required changes
Decision probably depends on how well you know the command line interface for SQLite vs. complexity of writing a small app to do what you want.
For #3, it would be similar to what you would do with a third party installer:
ReserveFile "myexe.exe"
...
SetOutPath $TEMP
File "myexe.exe"
ExecWait '"$TEMP\myexe.exe" /parameters"
alt option: http://sourceforge.net/projects/nsissqliteplug/
nsisSqlplugin::executeQuery "sqliteDatabase" "sql_query"
Limitations:
Currently the plugin executes only insert and update queries.
Related
Qt's QSqlDatabase can use SQLite as its backend. I'm trying to find out how to properly debug and optimize my SQLite queries (esp. their execution time) when they run inside a Qt application. This is esp. relevant when there is a difference between their behaviour in a usual SQLite client (such as the sqlite3 command-line client) and inside a Qt application.
Usual debugging and diagnostic techniques no longer work in this context; for example I can't use the dot commands to get information about indexes, track execution time etc. because these commands are specific to the sqlite3 CLI software.
Here are the techniques I found to be the most useful:
Use the CLI. The most obvious is to connect with the sqlite3 command-line client to the same database you are using from your application, and to look up information about indexes etc. there. It also helps to paste a query there that did not work when executed via Qt in order to get more detailed error messages. Obviously this technique won't work when the error is due to a difference of the SQLite3 library used inside Qt vs. the system's library.
Use DB Browser for SQLite. The open source DB Browser for SQLite (sqlitebrowser) is great for debugging issues with SQLite queries that happen in a Qt desktop application but not in the sqlite3 CLI tool. Because this tool is made with Qt itself and can be installed from the Ubuntu repos (sudo apt install sqlitebrowser), so it uses the same Qt as you would use when developing a Qt application for desktop use on that system. That way, it also uses the ame SQLite library that Qt itself uses, whether that is the system's SQLite library or Qt's bundled SQLite library (which depends on how Qt was compiled).
Note that with the default settings queries will take ~4 times longer to execute in sqlitebrowser than in the sqlite3 CLI or in your Qt application. This is approximately proportional for all queries, so it can still be used to improve query efficiency. It can probably be changed on the "PRAGMA" settings page of the software.
Use pragma functions. A difficulty when running diagnostic SQLite queries inside your Qt application is how to obtain their output. There will be no debug messages on the console from the SQLite library. But fortunately most PRAGMA queries that produce output (i.e. diagnostic ones) are also available as PRAGMA functions for use inside SELECT queries. This way, you can return information about indexes etc. inside the tabled results of your SELECT queries.
Use EXPLAIN queries. The SQLite EXPLAIN QUERY PLAN query (and to a lesser degree also the EXPLAIN query) are very useful to analyze why a query is slow. When run inside the sqlite3 CLI software, a EXPLAIN QUERY PLAN query produces a tree-like diagram drawn to the screen. So it does not seem to be a query one could use from inside Qt's SQL implementation, but that actually works. Because this represents actual tabular data, as can be seen from running such a query in any SQLite client that is not the sqlite3 CLI. Example output:
EXPLAIN QUERY PLAN SELECT [...];
id parent notused detail
6 0 0 SEARCH TABLE products USING COVERING INDEX idx_code (code=?)
10 0 0 SEARCH TABLE product_categories USING PRIMARY KEY (product_id=?)
20 0 0 SEARCH TABLE categories USING INTEGER PRIMARY KEY (rowid=?)
Recompile SQLite for debugging. The most extreme measure is to recompile Qt's SQLite3 library with debugging enabled and then to switch on debugging output with PRAGMA vdbe_debug=1;. This should print debug output to stdout while queries run. (I did not test this and it may still be that Qt intercepts this output. But probably not.)
Hello I wanted to ask if, to import the .sql update (after a git pull) I have to assemble and merge with the bash file (app/db_assembler) or if it's ok if I just launch the worldserver.exe and he will do it
Thanks
Short answer
No, the worldserver process will NOT update your database.
You need to use the DB-assembler bash script, as the instructions say.
More details
This is different than in TrinityCore, where it is a feature of the worldserver process to update the database.
In AzerothCore this task is a responsability of an external script, written in bash, the DB-assembler.
The advantage of having an external script to do this task instead of the worldserver is:
You don't need to compile and run the worldserver if you only need to create the database (useful when using or developing tools that only need the DBs)
The DB assembler is able to generate a unique SQL update file per each DB (by merging all the single SQL update files), which can be useful for debugging or development purposes
In general, it is better to delegate different software components for different tasks, instead of having a monolith doing everything
You can also make your own merge script and apply manually. Or just merge with the db_assembler.sh then apply manually.
Else refer to Francesco's answer
Well the thing is that when the program execute the query to copy a table to a file .CSV. Qt show me the next error.
"ERROR: syntax error at end of input
LINE 1: EXECUTE
Here are the code of the export action:
QSqlQuery qry;
qry.prepare("copy inventory to './inventory.csv'");
if(qry.exec()){
qDebug()<<"Succes";
}else{
qDebug()<<qry.lastError().text();
}
The version of qt is 5.4, used postgresql 9.3 and driver PQSQL working fine just can execute another's query very well like select.
Thanks.
You mentioned that you're using Qt's SQL interface and its PostgreSQL driver.
While Qt's PostgreSQL driver is built on top of PostgreSQL's standard client library libpq, as far as I can tell it does not offer support for lots of the functionality of libpq. In particular, there appears to be no way to access support for the COPY protocol, nor for LISTENing for asynchronous notifications.
You will have to:
libpq directly to COPY ... FROM STDIN
or use regular INSERT statements via Qt; or
Transfer the CSV input to the server, then use COPY ... FROM '/path/on/server' to read the input from a file on the server that the PostgreSQL database is running on, readable by the user the PostgreSQL database runs as.
(You could also submit a patch to Qt to add support for the COPY protocol, which shouldn't be too hard to implement, but is perhaps not the best choice if you're asking this.)
Using COPY needs superuser rights . Do not confuse with \COPY of
PostgreSQL
COPY TO requires absolute path to the output file. If 1st point is
considered, try removing the ./ in your output file name
You can refer to related posts:
post1
and
post2
I'm completely new to Qt. Actually I'm trying to build an app, which stores it's data to an encrypted sqlite database file. Ok, I've build sqlcipher successfully and found the files under ./libs (I'm on a Mac).
Where do I've to put the files in my Qt project for development, and later on, for deploy it with the app?
qDebug() << QSqlDatabase::drivers();
gives me
("QSQLITE", "QMYSQL", "QMYSQL3", "QODBC", "QODBC3", "QPSQL", "QPSQL7")
Thanks in advance.
I don't think a driver for SQLCipher exists in Qt. You'll only get the default drivers, which include SQLite.
I know two options: you use sqlcipher with its C API like a normal library, link to your app and you're done. Or you create the driver yourself. Creating that driver should be pretty simple as it should be almost identical to the one for sqlite, being the API almost identical. Simply linking the sqlite driver to sqlcipher instead of sqlite should be enough.
I found this online that should help you. But there are probably also other useful resources. That seems to simply re-use the sqlite plugin, linking to sqlcipher.
I've played around with SQLite on my Windows desktop before, but I've never used it in a web context and their web documentation is maddenigly unspecific about things like this. Essentially, I have free student webspace from my school (a /public/html/ directory) and I'd like to use it for a small data-driven web project. SQLite is my only (free) option and I'm wondering how to... "install" it in this context? More specifically, is it safe just to throw the files in the html directory and call it a day?
If it helps, I'm pretty sure it's Linux environment (they run Apache).
See if it's already installed. Try the following in a bash session:
touch test.db
sqlite3 test.db
If not, you'll have to download and install sqlite3.
Useful tip: if you've been trying to run the 'sqlite' binary, it probably doesn't exist. It's called 'sqlite3'.
SQLite is an embedded database; it is typically not installed, but compiled into whatever program is used to access the database.
All the typical server-side extension languages (PHP, Ruby, Python, Perl etc.) have support modules for SQLite.
You have to check which one of those are installed on the server, and whether SQLite support has been enabled for them.