I have 3 TQueries: qy_master, qy_detail, qy_detail2, master of qy_detail2 is qy_detail, master of qy_detail is qy_Master, all queries have corresponding data-sources, I placed queries in datamodule, when datamodule create I activate those queries.
In another form I used those queries, when trying 'qy_detail.open' it says 'EDbengine error : Tables is read-only' but no problem when opening qy_detail, I don't modify SQL statements, but I don't know why this error happens.
I also tried with qy_detail.Active := True; this statement also raise error,
I used SQL Server 2005 connected via BDE and ODBC datasources.
Please anyone help me to fix this.
Have you set TQuery.RequestLive = true? RequestLive is False by default forcing query to always return as read-only result set.
From documentation:
A TQuery can return two kinds of result sets: "live" as with TTable
component (users can edit data with data controls, and when a call to
Post occurs changes are sent to database), "read only" for display
purposes only. To request a live result set, set a query component's
RequestLive property to True...
Related
Using servicestack ormlite 6,4 and azure SQL server - using SQLServerDialect2012, we have an issue with an enums causing excessive stalling and timeouts.
If we just convert it to a string its quick as it should be.
var results = db.Select(q => q.SomeColumn == enum.value); -> 3,5 seconds
var results2 = db.Select(q => q.SomeColumn.tostring() == enum.value.tostring()); -> 0,08
we are using default settings so the enum in the db is defined as a varchar(255)
both queries give the same result.
to track the issue we wanted to see what its actually firing, but all we get is a query with some #1 #2 etc with no indication of what parameters where used or how they are defined.
All our attempts to get a 1:1 SQL string we can use to manually test the query and see the results have failed... mini profiler was the closest as it shows the parameter values...
but it does not contain the details necessary to recreate the used query and recreate the issue we have. (manually recreating the query gives 80ms as above)
Trying to get the execution plan with the query also fail.
db.ExecuteSql("SET STATISTICS PROFILE ON;");
var results = db.Select(q => q.SomeColumn == enum.value);
db.ExecuteSql("SET STATISTICS PROFILE OFF;");
only returns data, not any extra info i was hoping for.
I have not been able to find any sites or threads that explain how others get any kind of debug info.
What is the correct next step here?
OrmLite's Logging & Introspection page shows how you can view the SQL generated by OrmLite.
E.g. Configuring a debug logger should log the generated SQL and params:
LogManager.LogFactory = new ConsoleLogFactory(debugEnabled:true);
using sql server and delphi 10.3.1, and firedac.
I am using cached updates, with autocommit on.
I keep managing to get my data into a state where the record has been deleted from the database, and I have also deleted that record in the dataset.
then, when it attempts to commit the change to the database(where the data no longer exists), I get an error:
[my application] raised exception class emssqlNativeException with message [firedac][Phys][odbc][sqlncli11.dll] SQL_NO_DATA
and then I can't clear the cached updates flag on the dataset, because there is stuff 'sitting' there.
my question - how can I get it to NOT return that error? because it's really not an error, it's trying to delete a record that no longer exists. I am not finding ANY documentation on the update options on a query, so is there a flag there I need to set?
You can handle update errors in OnUpdateError and perform any additional checks before deciding how to proceed. Blindly pretending all deletes worked would be something like:
procedure TForm1.FDQuery1UpdateError(ASender: TDataSet; AException:
EFDException; ARow: TFDDatSRow; ARequest: TFDUpdateRequest; var AAction:
TFDErrorAction);
begin
if ARequest = ARDelete then AAction := eaApplied;
end;
Read the online help for OnUpdateError for more information.
static void clean() throws Exception {
final UserTransaction tx = InitialContext.doLookup("UserTransaction");
tx.begin();
try {
final DataSource ds = InitialContext.doLookup(Databases.ADMIN);
Connection connection1 = ds.getConnection();
Connection connection2 = ds.getConnection();
PreparedStatement st1 = connection1.prepareStatement("XXX delete records XXX"); // delete data
PreparedStatement st2 = connection2.prepareStatement("XXX insert records XXX"); // insert new data that is same primary as deleted data above
st1.executeUpdate();
st1.close();
connection1.close();
st2.executeUpdate();
st2.close();
connection2.close();
tx.commit();
} finally {
if (tx.getStatus() == Status.STATUS_ACTIVE) {
tx.rollback();
}
}
}
I have a web app, the DAO taking DataSource as the object to create individual connection to perform database operations.
So I have a UserTransaction, inside there are two DAO object doing separated action, first one is doing deletion and second one is doing insertion. The deletion is to delete some records to allow insertion to take place because insertion will insert same primary key's data.
I take out the DAO layer and translate the logic into the code above. There is one thing I couldn't understand, based on the code above, the insertion operation should fail, because the code (inside the UserTransaction) take two different connections, they don't know each other, and the first deletion haven't committed obviously, so second statement (insertion) should fail (due to unique constraint), because two database operation not in same connection, second connection is not able to detect uncommitted changes. But amazingly, it doesn't fail, and both statement can work perfectly.
Can anyone help explain this? Any configuration can be done to achieve this result? Or whether my understanding is wrong?
Since your application is running in weblogic server, the java-EE-container is managing the transaction and the connection for you. If you call DataSource#getConnection multiple times in a java-ee transaction, you will get multiple Connection instances joining the same transaction. Usually those connections connect to database with the identical session. Using oracle you can check that with the following snippet in a #Stateless ejb:
#Resource(lookup="jdbc/myDS")
private DataSource ds;
#TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
#Schedule(hour="*", minute="*", second="42")
public void testDatasource() throws SQLException {
try ( Connection con1 = ds.getConnection();
Connection con2 = ds.getConnection();
) {
String sessId1 = null, sessId2 = null;
try (ResultSet rs1 = con1.createStatement().executeQuery("select userenv('SESSIONID') from dual") ){
if ( rs1.next() ) sessId1 = rs1.getString(1);
};
try (ResultSet rs2 = con2.createStatement().executeQuery("select userenv('SESSIONID') from dual") ){
if ( rs2.next() ) sessId2 = rs2.getString(1);
};
LOG.log( Level.INFO," con1={0}, con2={1}, sessId1={2}, sessId2={3}"
, new Object[]{ con1, con2, sessId1, sessId2}
);
}
}
This results in the following log-Message:
con1=com.sun.gjc.spi.jdbc40.ConnectionWrapper40#19f32aa,
con2=com.sun.gjc.spi.jdbc40.ConnectionWrapper40#1cb42e0,
sessId1=9347407,
sessId2=9347407
Note that you get different Connection instances with same session-ID.
For more details see eg this question
The only way to do this properly is to use a transaction manager and two phase commit XA drivers for all databases involved in this transaction.
My guess is that you have autocommit enabled on the connections. This is the default when creating a new connection, as is documented here
https://docs.oracle.com/javase/tutorial/jdbc/basics/transactions.html
System.out.println(connection1.getAutoCommit());
will most likely print true.
You could try
connection1.setAutoCommit(false);
and see if that changes the behavior.
In addition to that, it's not really defined what happens if you call close() on a connection and haven't issued a commit or rollback statement beforehand. Therefore it is strongly recommended to either issue one of the two before closing the connection, see https://docs.oracle.com/javase/7/docs/api/java/sql/Connection.html#close()
EDIT 1:
If autocommit is false, the it's probably due to the undefined behavior of close. What happens if you switch the statements? :
st2.executeUpdate();
st2.close();
connection2.close();
st1.executeUpdate();
st1.close();
connection1.close();
EDIT 2:
You could also try the "correct" way of doing it:
st1.executeUpdate();
st1.close();
st2.executeUpdate();
st2.close();
tx.commit();
connection1.close();
connection2.close();
If that doesn't fail, then something is wrong with your setup for UserTransactions.
Depending on your database this is quite a normal case.
An object implementing UserTransaction interface represents a "logical transaction". It doesn't always map to a real, "physical" transaction that a database engine respects.
For example, there are situations that cause implicit commits (as well as implicit starts) of transactions. In case of Oracle (can't vouch for other DBs), closing a connection is one of them.
From Oracle's docs:
"If the auto-commit mode is disabled and you close the connection
without explicitly committing or rolling back your last changes, then
an implicit COMMIT operation is run".
But there can be other possible reasons for implicit commits: select for update, various locking statements, DDLs, and so on. They are database-specific.
So, back to our code.
The first transaction is committed by closing a connection.
Then another transaction is implicitly started by the DML on the second connection. It inserts non-conflicting changes and the second connection.close() commits them without PK violation. tx.commit() won't even get a chance to commit anything (and how could it? the connection is already closed).
The bottom line: "logical" transaction managers don't always give you the full picture.
Sometimes transactions are started and committed without an explicit reason. And sometimes they are even ignored by a DB.
PS: I assumed you used Oracle, but the said holds true for other databases as well. For example, MySQL's list of implicit commit reasons.
If auto-commit mode is disabled and you close the connection
without explicitly committing or rolling back your last changes,
then an implicit COMMIT operation is executed.
Please check below link for details:
http://in.relation.to/2005/10/20/pop-quiz-does-connectionclose-result-in-commit-or-rollback/
I've used Codeigniter Database Cache for a while and it works quite good, but now I have a weird problem with a specific query. The steps are as follow:
My cache directory is empty.
I open the URL /myproject/mycontroller/myaction/
The file is cached in mycontroller-myaction directory (I open the file with my notepad to be sure that it contains the correct data.
I open again the /myproject/mycontroller/myaction/ expecting the data to be retrieved from the cache and turns out that the data is retrieved from the database and the file y regenerated. I don't know why but the point is that the file generated is being useless.
If is important to you I give you the next info:
The query is a stored procedure.
I have other queries that are working perfectly.
I'd really appreciate your help, if you need specific data just let me know.
Thanks.
Using xdebug I found out that in the DB_driver.php file in the query function, there is a condition in the line 277 that says as follow:
// Is query caching enabled? If the query is a "read type"
// we will load the caching class and return the previously
// cached query if it exists
if ($this->cache_on == TRUE AND (stristr($sql, 'SELECT')))
{
if ($this->_cache_init())
{
$this->load_rdriver();
if (FALSE !== ($cache = $this->CACHE->read($sql)))
{
return $cache;
}
}
}
where the query must be a SELECT, and I am using a stored procedure and my model is:
public function cobertura($param1= NULL) {
$query = $this->db->query("[SP_NAME] ?", array($param1));
}
return $query->result();
}
So as I'm using a stored procedure instead of a SELECT statement, the condition returns FALSE and generates again the cache file.
How could I modify that function in order to detect my stored procedure as a valid statement?
Thank you very much.
Well, the solution for this problem was modify this
if ($this->cache_on == TRUE AND (stristr($sql, 'SELECT')))
by this
if ($this->cache_on == TRUE AND (stristr($sql, 'SELECT') OR strpos($sql, '[')))
This way I tell CI that when my sql statment starts with [ is a SELECT query too.
And when I have an stored procedure that is not a select statement simply disable the cache.
If you have a better solution you can share.
You should not use the query cache in CodeIgniter. It is not safe to use unless you know exactly what you are doing.
Instead I would create a cacheQuery function or something like it to at least give you control over caching for queries. The assumption that any query that returns data or might return data can be cached is very risky.
By replacing CI's attempted automation and doing it manually you will also gain some speed. If you xdebug profile all the guessing CI is doing about your queries add a lot of overhead to the query function.
The solution posted above might also be a bit dodgy because not all stored procedures return data and the square bracket could be anywhere in your queries so that check can get it wrong. It will return false if the first character and return true if the character is anywhere in the query even if it doesn't make up a stored procedure. For example, DELETE FROM table1 WHERE column1="[xxx]".
This kind of thing stristr($sql, 'SELECT') and strpos($sql, '[') are not good. CodeIgniter is simple, tidy, consistent and well organised but the actually quality of PHP code in it is extremely poor. To be fair, part of this is because it maintains compatibility with much older versions of PHP but there are several things that are inexplicably bad. When it comes to this kind of thing the CodeIgniter policy is "If it works 90% or more of the time then it's ok". This is of course not good for large serious enterprise applications.
By developing client server applications in Delphi + SQL Server I continuously face the problem to have an exact report of what an action caused on db.
A simple example is:
BEFORE: start "capturing" the DB
user changes a value in an editbox
the user presses a "save" button
AFTER: stop "capturing" the DB
I would like to have a tool that compares the before and after status (I manually capture the BEFORE and AFTER status).
I googled for this kind of tools but all I found are tools for doing data or schema comparison between more datasources.
Thanks.
The following is an extract for an application we have. This code is in a BeforePost event handler that is linked to all of the Dataset components in the application. This linking is done using code as there are a lot of datasets. This doesn't actually log the changes (just lists the fields) but it should be simple enough to change to meet your objective. I don't know if this is exactly right for what you are trying to achieve since you ask for a tool but it would be an effective way of creating a report of all changes
CurrentReport := Format('Table %s modified', [DataSet.Name]);
for i := 0 to DataSet.FieldCount - 1 do
begin
XField := DataSet.Fields[i];
if (XField.FieldKind = fkData) and (XField.Value <> XField.OldValue) then
begin
CurrentReport := CurrentReport + Format(', %s changed', [XField.FieldName])
end;
end;
Note that our code collects a report but only logs it after the post has been successfully completed