I have a ColdFusion server connected to MySQL database. Now I am changing the database to an existing MSSql server .. MSSql server has a similar database that of MySQL but the table names and column names are different. My question is that how can I map the new MSSql server to the ColdFusion server without changing the ColdFusion code.. Means without changing the table name and column names in ColdFusion code..
Thanks in advance
If the schemas are different (different column names and number of columns) then you probably have no choice but to refactor your CF code to reflect the new MSSQL schema. If there is a one to one relationship between the table and column names from one DB to the next you could use views - but it would make for a very confusing development environment. Again... each table would have to "match" for number of columns and types of data. Example
Old table "users"
firstname, lastname address
New table "tblUsers"
fname, lname, addr
Given the schemas above, you might have a query in your CF Code that looked like:
<cfquery name="getUsers" datasource="blah">
SELECT firstname, lastname, address
</cfquery>
So it would fail when you switched the DB. However, if you created a view like so:
CREATE VIEW [dbo].[Users]
AS
SELECT u.fname AS firstname,
u.lname AS lastname
u.addr AS address
FROM dbo.tblusers
Then your code would work. Again I am NOT recommending this. Your best course of action is to alter the schema to reflect your code or to refactor your code to work against the new schema. But technically it does answer your question :)
Unless you're already using ORM, here is no handy function or mapping mechanism in CF that would allow you to do this. There may be some manipulation at the driver level, or dipping into the java code that creates the sql strings to do text parsing there, but that's outside of my realm of expertise.
My guess, though, is that you have a lot of queries scattered throughout the application and are therefore daunted at the task of redoing all of them. Personally, I would refactor at least the data access of this app into one or more .cfc's. Even if all you do is wrap each query into a function call and replace the cfquery code with a function call, you're consolidating all of the database calls into one place and can change things much easier going forward.
Related
I use SQLDelight's MySQL dialect on my server. Recently I plan to migrate a table to combine many fields into a JSON field so the server code no longer needs to know the complex data structure. As part of the migration, I need to do something like this during runtime - when the sever sees a client with the new version, it knows the client won't access the old table anymore, so it's safe to migrate the record to new table.
INSERT OR IGNORE INTO new_table SELECT id, a, b, JSON_OBJECT('c', c, 'd', JSON_OBJECT(…)) FROM old_table WHERE id = ?;
The only problem is - Unlike the SQLite dialect, the MySQL dialect doesn't recognize JSON_OBJECT or other JSON expressions, even though in this case it doesn't have to - no matter how complex the query is, the result is not passed back to Kotlin.
I wish I could add the feature by myself, but I'm pretty new to Kotlin. So my question is: is there a way to evade the rigid syntax check? I could also retrieve from old table, convert the format in Kotlin, then write to the new table, but that would take hundreds of lines of complex code, instead of just one INSERT.
I assume from your links you're on the alpha releases already, in alpha03 you can add currently unsupported behaviour by creating a local SQLDelight module (see this example) and adding the JSON_OBJECT to the functionType override. Also new function types are one of the easiest things to contribute up to SQLDelight so if you want it in the next release
For the record I ended up using CONCAT with COALESCE as a quick and dirty hack to scrape the fields together as JSON.
I am not sure if this has been answered before but what I found i am not sure how to make work for me but here is my problem.
I have a database used to keep track of phones for multiple clients. What needs to be done is have a query that can be ran that will run against multiple databases on the same server. each database uses the same table name that I am looking at but the names are slightly different. I came up with this..
INSERT INTO `export db`.exportinfo2
SELECT *
FROM (SELECT * FROM `export db'.tentantnames).users
WHERE name = 'Caller ID:emergency' AND value > 0
What suppose to happen is from a table that has all the database names is is to got to each database and go into the table labeled users and run a where clause on the data then export results to a different database table
I know the code needs to be dynamic but I am not sure how to make it dynamic and function. The table that has all the names for the databases is automatically created every few days.. I am not sure what else needs to be said without sounding like i repeat myself but i just need help making a dynamic query that uses a table premade as database names and run a where statement on the same named table in each database which have their name stored in a different table.
You should look into Synonyms. It can be used to fulfill your purpose
I am currently working on a query in Access 2010 and I am trying to get the below query to work. I have the connection string between my local DB and the server that I am passing through to working just fine.
Select column1
, column2
from serverDB.dbo.table1
where column1 in (Select column1 from tbl_Name1)
In this situation table1 is the table on the server that I am passing through to get to, but the tbl_Name1 is the table that is actually in my Access DB that I am trying to use to create constraints on the data that I am pulling from the server.
When I try to run the query, I am getting the error that it doesn't think tbl_Name1 exists.
Any help is appreciated!
I just came across a solution that may help others in a similar situation.
This approach is easy because you can just run one query on your local Access database and get everything you need all at once. However, a lot of filtering/churning-through-results may be done on your own local computer behind the scenes, as opposed to on the remote server, so it may not necessarily be quick.
Steps
Create a query, make it a "Pass Through" query, and set up its "ODBC Connect Str" property to connect to the remote database.
Write the pass through query, something like SELECT RemoteId From RemoteTable and give your pass through query a name, maybe PassThroughQuery
Create a new query, make it a regular "Select" query.
Write your new query, using the pass through query you just created as a table in this new query (seems weird to use a query as a table, but it works) and join that PassThroughQuery "table" to your local table and filter it based on values in the local table, something like SELECT R.RemoteId, L.LocalValue FROM PassThroughQuery R INNER JOIN LocalTable L ON L.LocalId = R.RemoteId where L.LocalValue = 'SomeText'
This approach allows you to mix/join the results of a pass through query and the data in a local Access database table cleanly, albeit potentially slowly if there is a lot of data involved.
I think the issue is that a pass through query is one that is run on the server. Since one of the tables is located on the local Access file, it won't find the table.
Possible workaround if you must stay with the pass-through is you can build an SQL string with the results of the nested query rather than the query string itself (depending on the number of results this may or may not be practical)
e.g. Instead of Select column1 from tbl_Name1 you use "c1result1","c1result2",....
I'm working in a project that is divided into multiple modules. Each module have it's own independent database in mysql, but now, the modules need to obtain data between them. For example we're going to develop a new "admin" module, and every other modules need to access the data in the "admin" database. I know that I can make a query like
select * from admin.table
to obtain data from other database, but each module (and the new "admin" module) are created in CakePHP. I think one possible solution is use something like Synonyms (like the ones in Oracle or SQL Server), but MySQL don't support it. Someone have a better idea? Thanks
I have a feeling CakePHP can handle cross-database relations. Try setting $useDbConfig for each model to a connection for the respective database. CakePHP should generate multiple queries (atleast one per database connection) and join the results together for you. This approach should work fine for simple relations, but there might not be full support for relations such as HABTM.
How about using views:
create view admin_table as select * from admin.table
Then, you just need to set $tableName to admin_table.
I may be wrong, but I think querying is based on
select * from database.owner.table ... and the implied owner would be the "dbo" (database owner). So, you MIGHT be able to do the following...
select a1., b1. from database1.table1 a1, database2.table2 b1 where a1.fld1 = b1.fld1 ...
What is the use of SYNONYM in SQL Server 2008?
In some enterprise systems, you may have to deal with remote objects over which you have no control. For example, a database that is maintained by another department or team.
Synonyms can help you decouple the name and location of the underlying object from your SQL code. That way you can code against a synonym table even if the table you want is moved to a new server/database or renamed.
For example, I could write a query like this:
insert into MyTable
(...)
select ...
from remoteServer.remoteDatabase.dbo.Employee
but then if the server, or database, schema, or table changes it would impact my code. Instead I can create a synonym for the remote server and use the synonym instead:
insert into MyTable
(...)
select ...
from EmployeeSynonym
If the underlying object changes location or name, I only need to update my synonym to point to the new object.
http://www.mssqltips.com/sqlservertip/1820/use-synonyms-to-abstract-the-location-of-sql-server-database-objects/
Synonyms provide a great layer of abstraction, allowing us to use friendly and/or local names for verbosely named or remote tables, views, procedures and functions.
For Example
Consider you have the server1 and dbschema as ABC and table name as Employee and now you need to access the Employee table in your Server2 to perform a query operation.
So you have to use like Server1.ABC.Employee it exposes everything ServerName,SchemaName and TableName.
Instead of this you can create a synonym link Create Synonym EmpTable for Server1.ABC.Employee
So you can access like Select * from Peoples p1 inner join EmpTable emp where emp.Id=p1.ID
So it gives the advantages of Abstraction, Ease of change,scalability.
Later on if you want to change Servername or Schema or tablename, just you have to change the synonym alone and there is no need for you do search all and replace them.
If you used it than you will feel the real advantage of synonym. It can also combine with linked server and provide more advantages for developers.
An example of the usefulness of this
might be if you had a stored procedure
on a Users database that needed to
access a Clients table on another
production server. Assuming you
created the stored procedure in the
database Users, you might want to set
up a synonym such as the following:
USE Users; GO CREATE SYNONYM Clients
FOR Offsite01.Production.dbo.Clients;
GO
Now when writing the stored procedure
instead of having to write out that
entire alias every time you accessed
the table you can just use the alias
Clients. Furthermore, if you ever
change the location or the name of the
production database location all you
need to do is modify one synonym
instead of having to modify all of the
stored procedures which reference the
old server.
From: http://blog.sqlauthority.com/2008/01/07/sql-server-2005-introduction-and-explanation-to-synonym-helpful-t-sql-feature-for-developer/
Seems (from here) to create an alias for another table, so that you can refer to it easily. Like as
select * from table longname as ln
but permanent and pervasive.
Edit: works for user-defined functions, local and remote objects, not only tables.
I've been a long-time Oracle developer and making the jump to SQL Server.
But, another great use for synonyms is during the development cycle. If you have multiple developers modifying the same schema, you can use a synonym to point to your own schema rather than modifying the "production" table directly. That allows you to do your thing and other developers will not be impacted while you are making modifications and debugging.
I am glad to see these in SQL Server 2008...
A synonym is a database object that serves the following purposes:
Provides an alternative name for another database object, referred to as the base object, that can exist on a local or remote server.
Provides a layer of abstraction that protects a client application from changes made to the name or location of the base object.
Have never required the first one but the second issue is rather helpful.
msdn is your friend
You can actually create a synonym in an empty database and refer it to an object in another database, and thus make it work as it should even though it is in a completely empty database (besides the synonym that you created of course).