I'm trying to implement simple queries like SELECT * FROM TABLE_X WHERE XID = #id, but the problem that I'm having is that these queries would run on different databases (SQL Server and Oracle) for different application instances.
How to do it without to have to write each database a new set of queries?
Dapper is really closed to the database, and allow you to leverage pure sql tricks specific for a specific database. In my opinion you should use a query object pattern, so you will have an interface in front of each extraction /commit that would possibly change for SQL/Oracle.
I've downloaded the code of SqlMapper.cs and hacked SetupCommand to check if the command is from Oracle or SQL Server.
That was what I did:
if (cnn.GetType().Name.ToLowerInvariant().Contains("oracle"))
{
sql = sql.Replace('#', ':');
}
Related
I'd prefer to use raw SQL ( Mainly select + insert ) instead of O/R mapper, because it would be difficult to perform queries.
(The RDBMS is postgres9.4)
So the question is
Can I use raw SQL for logic part in Airflow?
You can create tasks that run raw SQL in a Postgres database directly using the PostgresOperator. You will need to set up your Postgres database as a Connection object in order for Airflow to know how to connect to the database.
I have an application that is supposed to support two types of databases SQL SERVER and ORACLE. So we've been working forever on SQL Server and now we are making this support.
My idea was to create a tool to generate the scripts of creating the database using CMO then convert those scripts to PL/SQL Oracle scripts and run them on Oracle.
My questions are:
Is this syntax conversion possible in code?
I need a guideline to make this kind of syntax conversion.
Do you have a better suggestion to maintain two types of databases (i mean when making a change of one of them, we dont have to make it to the other. we need a tool to make that change.)?
If you write using standard sql it should be mostly portable. Eg use fetch instead of top, SET #a=.. instead of Select #a=.. Use Merge for updates instead of join updates, CURRENT_TIMESTAMP instead of getdate() etc.
I am a new database intern working with a access front end and SQL server backend database. The database was custom made for the company. One of my assignments is to take scripts and apply them to make four new tables. I am aware that I need to make a new query for each new table but I don't know if I should make the query in SQL server management studio or the frontend access program. I have tried copying and pasting the given scripts into a new query in access but I get an error message "invalid SQL statement expected 'DELETE', 'INSERT'...". I decided to try to break done the program a little bit and tested the first line
IF EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id =OBJECT_ID(N'[dbo] .[FK_tblInstrumentInterfaceLog_tlkpInstrument]') AND parent_object_id = OBJECT_ID(N'[dbo].[tblInstrumentInterfaceLog]'))
but the same error message keeps popping up. I even tried just SELECT * FROM sys.foreign_keys, and I got the error message "could not find file...". I am very much a beginner and any guidance would be appreciated.Basically am I supposed to be applying these scripts the server SQL database or on the front end access program?
Are you using a pass-through query? i.e. not just a select query. Access needs to know where to send the query and since you are using TSQL not Access SQL this needs to be executed on the server.
Normally when you query a linked table the information of how to get the data (the connection string) is tied to the table. But for this kind of query you'll probably need to tell Access explicitly. Unless you are using an ADP/ADE, then the connection info travels with the program not the table.
As a general rule, you use SQL management studio (SSMS) to create and run those scripts. So the general accepted approach here is such scripts will not be placed in the front end. As noted such scripts if for some reason must be placed in the front end, then you have to create them as pass-though, but EVEN in this case you want to use the SSMS to create such quires.
So the answer here is you create the new scripts and make table queries in the back end, or in this case using the SQL server management studio.
The syntax checking, query editor etc. in recent versions of SSMS now has auto-complete etc. and you can test/write/update those scripts in SQL server. Once you have such a query or even several of them, then the resulting “several” statements can be pasted into a front end query that been created as pass-though. If you do not use a pass-though query, then you are creating and using and assuming client side SQL (JET (now called ACE)).
The client side has it own version of SQL syntax, and it is NOT 100% compatible with the SERVER SIDE. If you writing SQL in the client that is NOT pass though, then you using a linked table to SQL server. These linked tables thus will use local (JET/ACE) based SQL queries. The ODBC driver thus translates this SQL into server side compatible syntax. However the JET/ACE sql syntax is very limited when compared to SQL server and no server side commands exist in this SQL syntax for the client data engine (JET/ACE)
So for many quires, you will and can simply build such queries using the Access query builder.
However for SQL that needs to run 100% server side then such quires has to be setup as pass-though and are in most cased built + tested using SSMS.
I have database connection to database DB1. The only thing I could do - execute any t-sql statements including using stored procedures. I want to export the specific table (or even the specific rows of specific table) to my local database. As you can read abve, DBs are on diffrent servers meaning no direct connection is possible. Therefore question: Is it possible to write query that returns the other query to execute on local server and get data? Also note, that table contains BLOBs. Thanks.
If you have SQL Server Management Studio, you can use the data import function on your local database to get the data. It works as long as you have Read/Select access on the tables you are trying to copy.
If you have Visual Studio you can use the database tools in there to move data between two servers as long as you can connect to both from your workstation.
Needs Ultimate or Premium though:
http://msdn.microsoft.com/en-us/library/dd193261.aspx
RedGate has some usefull tools too:
http://www.red-gate.com/products/sql-development/sql-compare/features
Maybe you should ask at https://dba.stackexchange.com/ instead.
If you can login to the remote db (where you can only issue t-sql), you may create linked server on your local server to the remote and use it later directly in queries, like:
select * from [LinkedServerName].[DatabaseName].[SchemaName].[TableName]
I would like to copy parts of an Oracle DB to a SQL Server DB. I need to move the data because the Oracle box is being decommissioned. I only need the data for reference purposes so don't need indexes or stored procedures or contstaints, etc. All I need is the data.
I have a link to the Oracle DB in SQL Server. I have tested the following query, which seemed to work just fine:
select
*
into
NewTableName
from
linkedserver.OracleTable
I was wondering if there are any potential issues with using this approach?
Using SSIS (sql integration services) may be a good alternative especially if your table names are the same on both servers. Use the import wizard via and it should create the destination tables for you and let you edit any mappings.
The only issue I see with that is you will need to execute that of course for each and every table you need. Glad you are decommissioning the oracle server :-). Otherwise if you are not concerned with indexes or any of the existing sprocs I don't see any issue in what you are doing.
The "select " approach could be very slow if tables are large. Consider writing pro*C in that case or use Fastreader http://www.wisdomforce.com/products-FastReader.html
A faster and easier approach might be to use the Data Transformation Services, depending on the number of objects you're trying to copy over.