Using Delphi 10.3.3, mainly under Windows10, I have a number of [FireDAC] TFDTable components accessing an SQL Server DB.
Everything worked fine in delphi 10.2.3 but in the Rio version, I find that those TFDtables which have an indexname set and which access a DB whose name has a space in it, fail with the message "[FireDAC]{DatS]-2 Object [PK_DEPT] is not found."
An example of the table definition in the dfm is:
object tbHODEPT: TFDTable
IndexName = 'PK_DEPT'
ConnectionName = 'HEADOFFICE'
FetchOptions.AssignedValues = [evMode]
FetchOptions.Mode = fmAll
UpdateOptions.UpdateTableName = 'DEPT'
TableName = 'DEPT'
The connection, "HEADOFFICE", is a TFDConnection descendant which just adds the credentials for the relevant DB at open-time. I have noticed that if I supply a fully qualified TableName property (e.g. '[Some DBname].dbo.[DEPT') then the problem does not occur. But setting the DBname at design time is undesirable as we allow the DB names to be configurable.
Barring a solution, my options seem to be
Renaming the problematic DB, and
Changing all of the affected TFDTables to use indexfieldnames instead. (This works OK).
Ideas welcome.
Related
I work with large databases that needs to be stored into a server.
So, to work with them on Rstudio I have to open a connection to my Microsoft SQL Server with the dbConnect function :
conn <- dbConnect(odbc(),"myconnection",uid="***",pwd="***",schema="dbo",access="readonly")
and in order to use dplyr, I have to create data references with the tbl function :
data <- tbl(conn, "data")
But one of the online dataframe contains a columns that I can't read because I dont have the access, but I can read everything else.
The SQL query behind the tbl() function is :
SELECT * FROM data
and this is my problem.
Even when I try to select a specific column it doesn't work (see below), so I can't create my references and I can't work.
select(tbl(conn, "data"), "columnX")
=
SELECT columnX FROM data
I think this is the tbl() function and the call of "SELECT *" that blocks me.
Do you know what can I do ? Is there smilar functions that could resolve my problem ?
If you know the columns that you have access to, then one option is to bypass the default access SELECT * FROM ... with your own SQL query.
A remote table is defined by two components:
The database conneciton
The query to the database
When you connect with the default approach tbl(conn, 'data') then it defaults to a query SELECT * FROM data.
But here is another approach:
custom_query = 'SELECT columnX FROM data'
remote_table = tbl(conn, dbplyr::sql(customer_query))
I'm using ADODB connections to connect to a database which none of my other colleagues understand how to connect to. So far I've got as far as being able to see all the available tables via 2 methods:
Dim ado as object
set ado = CreateObject("ADODB.Connection")
Call ado.open("...")
set rs = ado.Execute("SELECT * FROM sys.objects WHERE type='U'")
and also
const adTable = 20
Set rstSchema = ado.OpenSchema(adTable)
Do Until rstSchema.EOF
Debug.Print rstSchema("TABLE_NAME")
rstSchema.MoveNext
Loop
But the part which is confusing me is selecting from the tables directly... I expected to be able to do:
select * from <<TABLENAME>>
where <<TABLENAME>> was one of the table names returned by the above 2 methods. However whenever I do this I get the error in the title:
Invalid object name '<<TABLENAME>>'.
So how exactly am I meant to access the data in the tables identified from OpenSchema() method. Is there another method which I am unfamiliar with?
As discussed with itsLex in the comments:
In SQL Server terms:
select * from <<Database>>.<<Owner>>.<<TableName>>
Alternatively you can use the USE statement as follows:
USE <<Database>>;
select * from <<TableName>>;
I am creating a DB synchronization engine using SQL CLR Triggers in Microsoft SQL Server 2012. These triggers do not call a stored procedure or function (and thereby have access to the INSERTED and DELETED pseudo-tables but do not have access to the ##procid).
Differences here, for reference.
This "sync engine" uses mapping tables to determine what the table and field maps are for this sync job. In order to determine the target table and fields (from my mapping table) I need to get the source table name from the trigger itself. I have come across many answers on Stack Overflow and other sites that say that this isn't possible. But, I've found one website that provides a clue:
Potential Solution:
using (SqlConnection lConnection = new SqlConnection(#"context connection=true")) {
SqlCommand cmd = new SqlCommand("SELECT object_name(resource_associated_entity_id) FROM sys.dm_tran_locks WHERE request_session_id = ##spid and resource_type = 'OBJECT'", lConnection);
cmd.CommandType = CommandType.Text;
var obj = cmd.ExecuteScalar();
}
This does in fact return the correct table name.
Question:
My question is, how reliable is this potential solution? Is the ##spid actually limited to this single trigger execution? Or is it possible that other simultaneous triggers will overlap within this process id? Will it stand up to multiple executions of the same and/or different triggers within the database?
From these sites, it seems the process Id is in fact limited to the open connection, which doesn't overlap: here, here, and here.
Will this be a safe method to get my source table?
Why?
As I've noticed similar questions, but all without a valid answer for my specific situation (except that one). Most of the comments on those sites ask "Why?", and in order to preempt that, here is why:
This synchronization engine operates on a single DB and can push changes to target tables, transforming the data with user-defined transformations, automatic source-to-target type casting and parsing and can even use the CSharpCodeProvider to execute methods also stored in those mapping tables for transforming data. It is already built, quite robust and has good performance metrics for what we are doing. I'm now trying to build it out to allow for 1:n table changes (including extension tables requiring the same Id as the 'master' table) and am trying to "genericise" the code. Previously each trigger had a "target table" definition hard coded in it and I was using my mapping tables to determine the source. Now I'd like to get the source table and use my mapping tables to determine all the target tables. This is used in a medium-load environment and pushes changes to a "Change Order Book" which a separate server process picks up to finish the CRUD operation.
Edit
As mentioned in the comments, the query listed above is quite "iffy". It will often (after a SQL Server restart, for example) return system objects like syscolpars or sysidxstats. But, it seems that in the dm_tran_locks table there's always an associated resource_type of 'RID' (Row ID) with the same object_name. My current query which works reliably so far is the following (will update if this changes or doesn't work under high load testing):
select t1.ObjectName FROM (
SELECT object_name(resource_associated_entity_id) as ObjectName
FROM sys.dm_tran_locks WHERE resource_type = 'OBJECT' and request_session_id = ##spid
) t1 inner join (
SELECT OBJECT_NAME(partitions.OBJECT_ID) as ObjectName
FROM sys.dm_tran_locks
INNER JOIN sys.partitions ON partitions.hobt_id = dm_tran_locks.resource_associated_entity_id
WHERE resource_type = 'RID'
) t2 on t1.ObjectName = t2.ObjectName
If this is always the case, I'll have to find that out during testing.
How reliable is this potential solution?
While I do not have time to set up a test case to show it not working, I find this approach (even taking into account the query in the Edit section) "iffy" (i.e. not guaranteed to always be reliable).
The main concerns are:
cascading (whether recursive or not) Trigger executions
User (i.e. Explicit / Implicit) transactions
Sub-processes (i.e. EXEC and sp_executesql)
These scenarios allow for multiple objects to be locked, all at the same time.
Is the ##SPID actually limited to this single trigger execution? Or is it possible that other simultaneous triggers will overlap within this process id?
and (from a comment on the question):
I think I can join my query up with the sys.partitions and get a dm_trans_lock that has a type of 'RID' with an object name that will match up to the one in my original query.
And here is why it shouldn't be entirely reliable: the Session ID (i.e. ##SPID) is constant for all of the requests on that Connection). So all sub-processes (i.e. EXEC calls, sp_executesql, Triggers, etc) will all be on the same ##SPID / session_id. So, between sub-processes and User Transactions, you can very easily get locks on multiple resources, all on the same Session ID.
The reason I say "resources" instead of "OBJECT" or even "RID" is that locks can occur on: rows, pages, keys, tables, schemas, stored procedures, the database itself, etc. More than one thing can be considered an "OBJECT", and it is possible that you will have page locks instead of row locks.
Will it stand up to multiple executions of the same and/or different triggers within the database?
As long as these executions occur in different Sessions, then they are a non-issue.
ALL THAT BEING SAID, I can see where simple testing would show that your current method is reliable. However, it should also be easy enough to add more detailed tests that include an explicit transaction that first does some DML on another table, or have a trigger on one table do some DML on one of these tables, etc.
Unfortunately, there is no built-in mechanism that provides the same functionality that ##PROCID does for T-SQL Triggers. I have come up with a scheme that should allow for getting the parent table for a SQLCLR Trigger (that takes into account these various issues), but haven't had a chance to test it out. It requires using a T-SQL trigger, set as the "first" trigger, to set info that can be discovered by the SQLCLR Trigger.
A simpler form can be constructed using CONTEXT_INFO, if you are not already using it for something else (and if you don't already have a "first" Trigger set). In this approach you would still create a T-SQL Trigger, and then set it as the "first" Trigger using sp_settriggerorder. In this Trigger you SET CONTEXT_INFO to the table name that is the parent of ##PROCID. You can then read CONTEXT_INFO() on a Context Connection in a SQLCLR Trigger. If there are multiple levels of Triggers then the value of CONTEXT INFO will get overwritten, so reading that value must be the first thing you do in each SQLCLR Trigger.
This is an old thread, but it is an FAQ and I think I have a better solution. Essentially it uses the schema of the inserted or deleted table to find the base table by doing a hash of the column names and comparing the hash with the hashes of tables with a CLR trigger on them.
Code snippet below - at some point I will probably put the whole solution on Git (it sends a message to Azure Service Bus when the trigger fires).
private const string colqry = "select top 1 * from inserted union all select top 1 * from deleted";
private const string hashqry = "WITH cols as ( "+
"select top 100000 c.object_id, column_id, c.[name] "+
"from sys.columns c "+
"JOIN sys.objects ot on (c.object_id= ot.parent_object_id and ot.type= 'TA') " +
"order by c.object_id, column_id ) "+
"SELECT s.[name] + '.' + o.[name] as 'TableName', CONVERT(NCHAR(32), HASHBYTES('MD5',STRING_AGG(CONVERT(NCHAR(32), HASHBYTES('MD5', cols.[name]), 2), '|')),2) as 'MD5Hash' " +
"FROM cols "+
"JOIN sys.objects o on (cols.object_id= o.object_id) "+
"JOIN sys.schemas s on (o.schema_id= s.schema_id) "+
"WHERE o.is_ms_shipped = 0 "+
"GROUP BY s.[name], o.[name]";
public static void trgSendSBMsg()
{
string table = "";
SqlCommand cmd;
SqlDataReader rdr;
SqlTriggerContext trigContxt = SqlContext.TriggerContext;
SqlPipe p = SqlContext.Pipe;
using (SqlConnection con = new SqlConnection("context connection=true"))
{
try
{
con.Open();
string tblhash = "";
using (cmd = new SqlCommand(colqry, con))
{
using (rdr = cmd.ExecuteReader(CommandBehavior.SingleResult))
{
if (rdr.Read())
{
MD5 hash = MD5.Create();
StringBuilder hashstr = new StringBuilder(250);
for (int i=0; i < rdr.FieldCount; i++)
{
if (i > 0) hashstr.Append("|");
hashstr.Append(GetMD5Hash(hash, rdr.GetName(i)));
}
tblhash = GetMD5Hash(hash, hashstr.ToString().ToUpper()).ToUpper();
}
rdr.Close();
}
}
using (cmd = new SqlCommand(hashqry, con))
{
using (rdr = cmd.ExecuteReader(CommandBehavior.SingleResult))
{
while (rdr.Read())
{
string hash = rdr.GetString(1).ToUpper();
if (hash == tblhash)
{
table = rdr.GetString(0);
break;
}
}
rdr.Close();
}
}
if (table.Length == 0)
{
p.Send("Error: Unable to find table that CLR trigger is on. Message not sent!");
return;
}
….
HTH
I want to create VIEW definitions on MS Access. I have used following CREATE VIEW Statement:
SELECT
MFP.FollowUpPlan_Id,
MFP.FollowUpPlan_Name AS PlanName,
DFP.Sequence_No AS SequenceNo,
MFS.FollowUpSchedule_Name AS ScheduleName
FROM
MAS_FollowUp_Plan AS MFP,
DET_FollowUp_Plan AS DFP,
MAS_FollowUp_Schedule AS MFS
WHERE
(((MFP.FollowUpPlan_Id)=DFP.FollowUpPlan_Id) AND
((DFP.FollowUpSchedule_Id)=MFS.FollowUpSchedule_Id)) AND
MFP.is_Deleted = FALSE AND
DFP.is_Deleted = false
ORDER BY
MFP.FollowUpPlan_Id, DFP.Sequence_No;
but it throw an error:
Only Simple Select Queries are allowed in view.
Please Help, Thanks in Advance.
The issue here, as Jeroen explained, is a limitation of Access' CREATE VIEW statement. For this case, you can use CREATE PROCEDURE instead. It will create a new member of the db's QueryDefs collection --- so from the Access user interface will appear as a new named query.
The following statement worked for me using ADO from VBScript. From previous Delphi questions on here, my understanding is that Delphi can also use ADO, so I believe this should work for you, too.
CREATE PROCEDURE ViewSubstitute AS
SELECT
MFP.FollowUpPlan_Id,
MFP.FollowUpPlan_Name AS PlanName,
DFP.Sequence_No AS SequenceNo,
MFS.FollowUpSchedule_Name AS ScheduleName
FROM
(MAS_FollowUp_Plan AS MFP
INNER JOIN DET_FollowUp_Plan AS DFP
ON MFP.FollowUpPlan_Id = DFP.FollowUpPlan_Id)
INNER JOIN MAS_FollowUp_Schedule AS MFS
ON DFP.FollowUpSchedule_Id = MFS.FollowUpSchedule_Id
WHERE
MFP.is_Deleted=False AND DFP.is_Deleted=False
ORDER BY
MFP.FollowUpPlan_Id,
DFP.Sequence_No;
You cannot mix ORDER BY with JOIN when creating views in Access. It will get you the error "Only simple SELECT queries are allowed in VIEWS." (note the plural VIEWS)
Having multiple tables in the FROM is a kind of to JOIN.
either remove the ORDER BY,
or have only one table in the FROM and no JOINs.
I remember from the past (when I did more Access stuff than now) seeing this for a large query with a single table select with an ORDER BY as well.
The consensus is that you should not have ORDER BY in views anyway, so that is your best thing to do.
Another reason that you can get the same error message is if you add parameters or sub selects. Access does not like those in views either, but that is not the case in your view.
Declare variable olevarCatalog ,cmd as OleVariant in Delphi, Uses ComObj
olevarCatalog := CreateOleObject('ADOX.Catalog');
olevarCatalog.create(YourConnectionString); //This Will create MDB file.
// Using ADO Query(CREATE TABLE TABLEName....) add the required Tables.
// To Insert View Definition on MDB file.
cmd := CreateOleObject('ADODB.Command');
cmd.CommandType := cmdText;
cmd.CommandText := 'ANY Kind of SELECT Query(JOIN, OrderBy is also allowed)';
olevarCatalog.Views.Append('Name of View',cmd);
cmd := null;
This is a best way to Create MS ACCESS File(.MDB) and VIEWs using Delphi.
I am new to PowerBuilder.
I want to retrieve the data from MSAccess tables and update it to corresponding SQL tables. I am not able to create a permanent DSN for MSAccess because I have to select different MSAccess files with same table information. I can create a permanent DSN for SQL server.
Please help me to create DSN dynamically when selecting the MSAccess file and push all the tables data to SQL using PowerBuilder.
Also give the full PowerBuilder code to complete the problem if its possible.
In Access we strongly suggest not using DSNs at all as it is one less thing for someone to have to configure and one less thing for the users to screw up. Using DSN-Less Connections You should see if PowerBuilder has a similar option.
Create the DSN manually in the ODBC administrator
Locate the entry in the registry
Export the registry syntax into a .reg file
Read and edit the .reg file dynamically in PB
Write it back to the registry using PB's RegistrySet ( key, valuename, valuetype, value )
Once you've got your DSN set up, there are many options to push data from one database to the other.
You'll need two transaction objects in PB, each pointing to its own database. Then, you could use a Data Pipeline object to manage the actual data transfer.
You want to do the DSNLess connection referenced by Tony. I show an example of doing it at PBDJ and have a code sample over at Sybase's CodeXchange.
I am using this code, try it!
//// Profile access databases accdb format
SQLCA.DBMS = "OLE DB"
SQLCA.AutoCommit = False
SQLCA.DBParm = "PROVIDER='Microsoft.ACE.OLEDB.12.0',DATASOURCE='C:\databasename.accdb',DelimitIdentifier='No',CommitOnDisconnect='No'"
Connect using SQLCA;
If SQLCA.SQLCode = 0 Then
Open ( w_rsre_frame )
else
MessageBox ("Cannot Connect to Database", SQLCA.SQLErrText )
End If
or
//// Profile access databases mdb format
transaction aTrx
long resu
string database
database = "C:\databasename.mdb"
aTrx = create transaction
aTrx.DBMS = "OLE DB"
aTrx.AutoCommit = True
aTrx.DBParm = "PROVIDER='Microsoft.Jet.OLEDB.4.0',DATASOURCE='"+database+"',PBMaxBlobSize=100000,StaticBind='No',PBNoCatalog='YES'"
connect using aTrx ;
if atrx.sqldbcode = 0 then
messagebox("","Connection success to database")
else
messagebox("Error code: "+string(atrx.sqlcode),atrx.sqlerrtext+ " DB Code Error: "+string(atrx.sqldbcode))
end if
// do stuff...
destroy atrx