Disclaimer: I am a n00b.
It seems like ODBC does not support a BOOLEAN type? Is this true?
If so, what's the standard kludgearound?
Edit: I am using ADO with Delphi on Windows to write the data, but PHP 5 to read it back.
SQL itself has traditionally not supported a boolean type, so ODBC is just reflecting this. As ODBC is intended to provide portability across databases, it is generally better to implement booleans in the database as one of the standard types, such as CHAR(1), containing either 'Y' or 'N', rather than use a vendor specific type.
There's SQL_C_BIT, but you need to lookup what a given driver uses for each SQL type. For example, MySQL uses SQL_C_CHAR for bool.
I believe it depends on the actual SQL server implementation. You can check the ODBC driver/datasource settings, if you are doing it under Windows -- there might be options such as Bool As Char, or something.
Related
I have setup a linked server in SQL Server 2008 R2 in order to access an Oracle 11g database. The MSDASQL provider is used to connect to the linked server through the Oracle Instant Client ODBC driver. The connection works well when using the OPENQUERY with the below syntax:
SELECT *
FROM OPENQUERY(LINKED_SERVER, 'SELECT * FROM SCHEMA.TABLE')
However, went I try to use a four part name using the below syntax:
SELECT *
FROM LINKED_SERVER..SCHEMA.TABLE
I receive the following error:
Msg 7318, Level 16, State 1, Line 1
The OLE DB provider "MSDASQL" for linked server "LINKED_SERVER" returned an invalid column definition for table ""SCHEMA"."TABLE"".
Does anyone have any insight on what my be causing the four part name query to fail while the OPENQUERY one works without any problems?
The correct path to follow is to use OPENQUERY function because your linked server is Oracle: the four name syntax will work fine for MSSQL servers, essentially because they understand T-SQL.
With very simple queries, a 4 part name can accidentally work but not often if you are in a real scenario. In your case, the SELECT * is returning all the columns, and in your case one of the column definition is not compatible with SQL Server. Try another table or try to select a single simple column (e.g. a CHAR or a NUMBER), maybe it will work without problem.
In any case, using distributed queries can be tricky sometime. Database itself does some optimizations before executing commands, so it is important for the database to know what it can do and what it can't. If the DB thinks the linked server is MSSQL, it will take some action that may not work with Oracle.
When using four part name syntax with a linked DB different from MSSQL, you will have other problems as well, for example using database builtin functions (i.e. to_date() Oracle function will not work because MSSQL would want to use its own convert() function, and so on).
So again, if the linked server is not a MSSQL, the right choice is to use OPENQUERY and passing it a query that use a syntax valid against the linked server SQL dialect.
If you use the OLEDB provider for Oracle you can query without using openquery
Specifically, what character encoding does SQLDataSources use?
On my Windows 7 machine (set to New Zealand English) it seems to use CP1252. I can't find any mention of character encodings in the documentation.
It depends of database you use. For PostgreSQL I use SET client_encoding to <encoding>; after connecting do database. For Informix there is Client Encoding option available on Environment tab. For Oracle I use NLS_LANG environment setting.
I've done some experimentation and determined that data source names are in unicode. SQLDataSources gives you the name converted to the system code page, replacing characters that can't be converted with '?'. This is about as useful as you might expect. The undocumented function SQLDataSourcesW gives the name encoded in UTF-16.
Could someone please explain how to obtain a list of all existing databases on a PostgreSQL server, to which the user already has access, using Qt? PostgreSQL documentation suggests the following query:
SELECT datname FROM pg_database WHERE datistemplate = false;
What are the correct parameters to the following functions:
QSqlDatabase::setDatabaseName(const QString & name) //"postgres" or "pg_database"?
QSqlDatabase::setUserName(const QString & name) //actual user name?
QSqlDatabase::setPassword(const QString & password) //no password? or user password?
Much appreciated. Thank you in advance.
You appear to have already answered the first part of your question. Connect to the postgres or template1 database and issue the query you've quoted above to get a list of databases. I'm guessing - reading between the lines - that you don't know how to connect to PostgreSQL to send that query, and that's what the second part of your question is about. Right?
If so, the QSqlDatabase accessor functions you've mentioned are used to set connection parameters, so the "correct" values depend on your environment.
If you want to issue the query above - to list databases - then you would probably want to connect to the postgres database as it always exists and isn't generally used for anything specific, it's there just to be connected to. That means you'd call setDatabaseName("postgres");. Passing pg_database to setDatabaseName would be nonsensical, since pg_database is the pg_catalog.pg_database table, it isn't a database you can connect to. pg_database is one of those odd tables that exists in every database, which might be what confused you.
With the other two accessors specify the appropriate username and password for your environment, same as you'd use for psql; there's no possible way I could tell you which ones to use.
Note that if you set a password but one isn't required because authentication is done over unix socket ident, trust, or other non-password scheme the password will be ignored.
If this doesn't cover your question, consider editing it and explaining your problem in more detail. What've you tried? What didn't work how you expected? Error messages? Qt version?
We have our application developed and tested with sql server 2008r2 using ASP.NET on windows server. Now we have a requirement to move the database from windows to oracle on red hat linux.
We haven't yet setup the infrastructure to test the same. I would like to know in the meantime if anyone has successfully done this kind of thing. Pointers to any resources will be a great advantage.
Is changing the connection string the only thing that needs to be done or are there any specific configuration in Linux to allow this?
I will verify this once I get the environment ready, but as a headstart if anyone has any similar experience, do share.
Thanks in advance.
P.S: For migration of table structure, storedprocedures etc to oracle we will be using the Sql Developer tool.
I would like to answer my question,because, migration to oracle is not that straight forward, but there are some tips that may help anyone migrate to oracle on windows or linux with less headache.
The first thing the Sql developer tool does a good job of migrating sqlserver schema and data to oracle including storedprocedures, constraints, triggers etc.
It also does a good job of datatype mapping and provides option to remap datatype if required.
Some caveats and precautions.
Oracle has a limitation on the length of stored procedure names of about 30 characters. This is the area you need to resort to some manual renaming as when migration SP's or identifiers whose name is greater than 30 characters may get truncated.
The other common issue that you may face is respect to date insertion and formatting. You can use the following snippet to avoid the headache. The common error will be "Not a valid month."
OracleConnection conn = new OracleConnection(oradb); // C#
conn.Open();
OracleGlobalization session = conn.GetSessionInfo();
session.DateFormat = "DD.MM.RR"; // change the format as required here
conn.SetSessionInfo(session);
The most annoying error would be well character to numeric conversion when inserting or updating data or related error.
The issue here is when you add parameters to command object for sql provider, the binding happens by name, but forOracle.DataAccess the default binding is by position. Here's the post that saved me lot of headache.
ODP .NET Parameter problem with uint datatype
What you can do is set the command.BindByName = true;
When migrating SP's that returns data, oracle creates an out parameter ref cursor. This needs to be taken care of while constructing command parameters.
For e.g.
OracleParameter refp = new Oracle.DataAccess.Client.OracleParameter("cv_1", OracleDbType.RefCursor, ParameterDirection.InputOutput);
command.Parameters.Add(refp);
Also the sqlserver requires parameters to SP be prefixed with "#" and oracle doesn't. This can be easily taken care of in your data layer.
Also since there is no bit datatype in Oracle, number(1) works fine. You may need to convert your bool to numeric, if required.
Hope this helps someone avoid a migration headaches. I will post more issues if I encounter.
We commonly use MS Visual Foxpro v9.0 SP1, the language, tables, and reports. However, sometimes we use an ODBC driver to connect to the tables. The ODBC driver was written for Foxpro v6, and doesn't support certain nested selects, autoincrement fields, or embedded casts.
We would like to find an alternative to what we have. It could be another ODBC driver that works with Visaul Foxpro v9, or a complete alternative to ODBC. Is there such a thing?
Thanks.
(Talk about reuse, just answered this in another thread today)
If you are looking for an ODBC driver for VFP databases and tables you might consider looking at Advantage Database from iAnywhere. The have a local engine and a server engine. The local engine has the engine to access DBF data, but for your case, it also has an ODBC drive that works with VFP data up to and including the current Visual FoxPro 9. The local engine and the included ODBC driver are free.
http://www.sybase.com/ianywhere
You can via COM+ and do almost anything in VFP, however, you have security issues through Admin Tools, Component Services..
You can either build as a single-threaded or multi-threaded DLL.
Once registered, and the typelibrary info is "Add Referenced" to a C# (or other) app, you can make function calls with whatever parameters you need. There are many things you can return back, but typically tables, I send back as XML (via Foxpro's XMLAdapter class), then stream convert to a table once in C#. Its been a while since I worked it that way, but that give tremendous flexibility as you can do your queries, scan loops, and other complex conditional testing and updating of the cursor before generating out the XML and returning it as a string.
DEFINE CLASS YourClass as CUSTOM OLEPUBLIC
FUNCTION GetMyData( lcSomeString as String)
select * from (YourPath + "SomeTable" ) where ... into cursor C_SomeCursor readwrite
.. any other manipulation, testing, etc...
oXML = CREATEOBJECT( "xmladapter" )
lcXML = ""
oXML.AddTableSchema( "C_SomeCursor" )
oXML.ToXML( "lcXML", "", .f. )
return lcXML
ENDFUNC
ENDDEFINE