is there a windows xp utility to make a database such that its support by sql server, oracle, and other db management systems.
the database schema is very huge so i would like to know what to use to make it so its protable from sql server to oracle if future demands that change?
In short, what you seek is nearly impossible to do successfully. Every database product has enough quirks that building such database would not perform well and would be too limiting in terms of the features you were able to use. I.e, you have to play the game of lowest common denominator with respect to features that all products implement you want to support. A far better solution is to abstract the data layer into its own library accessed via interfaces so that you can swap out your data layer. ORMs, as Rafael E. Belliard suggested, makes this simpler but it can also be done manually.
I would recommend building your database using an ORM like Hibernate for Java (or NHibernate for .NET). This would allow you to seamlessly transition from one database type to the other with little to no issues. They would allow you to logically create the database schema without a specific database in mind, which you could then move from one database to the other.
I have created applications which change from SQL Server to MySQL to Oracle to MS Access to SQLite easily (clients love that flexibility).
However, you would need to know your way around programming...
Related
In my CS program, I was told I should learn SQL for my databases.
If I'm using PostgreSQL, do I also need a SQL server to go along with it? Is PostgreSQL a language, a server, or both? Is there even a SQL language or is it only servers?
Background: I downloaded Postgres because hey, that has SQL in the name, it works and I'm under the impression it's a pretty good choice anyway. But I couldn't figure out through their website if it needs a companion server, so I went looking for one and found AWS RDS.
The impression I have is that Postgres is the language and AWS RDS is the server, and they serve different functions. But I'm not sure about any of that.
Seems you're learning too many new topics at the same time.
Ok. I'll try to answer.
SQL stands for 'Structured Query Language', and serves as a 'standard' for many vendors that in much ways respects its fundamentals. Oracle, MySQL (now owned by Oracle), MariaDB and PostreSQL are some vendors.
Main thing with SQL code I would recommend you to identify every time you look at it, is to understand if it belongs to DML or DDL. DML stands for 'Data Manipulation Language' and refers to SQL instructions which 'modifies' data. DDL stands for 'Data Declaration Language' which defines or 'alter' de structure on which data will be stored.
Another important concept is atomicity of data manipulation. You can confirm a change or roll it back before it is persisted. This thing corresponds to 'commit' changes or do a 'rollback'. It's some kind of advanced concept, but generally happens "automatically" with standard client configurations. Later, you would have to know about it while programming some system module which interacts with databases.
When you think of the SQL 'server', it refers to the software configured/installed which has the responsability of manage persistence of data within some kind of 'instance' of persistence, allocated in some system with data storage capabilities. AWS implements this service in the cloud, and RDS is the product which supports many kind of SQL flavors to choose (Oracle, Postgresql, etc.)
If you are comfortable with Docker, I recomend you learn the basics which would help you setup and destroy databases many times, which is useful to develop and test locally. Next command, let you start a Postgresql database configured with open port 5432. You can see the server log through docker and use some SQL client to get connected. When you press Ctrl+C everything will be deleted. Of course there are other ways to keep data persistent, but this command would be an easy starting point.
$ docker run --rm -p 5432:5432 --name some-postgres-container-name -e POSTGRES_PASSWORD=mysecretpassword postgres:13.3
Side note: it's better to get used to work with specific docker image versions always (not 'latest').
More details of it usage here: https://hub.docker.com/_/postgres/
if I'm using PostgreSQL, do I also need a SQL server to go along with
it? Is PostgreSQL a language, a server, or both? Is there even a SQL
language or is it only servers lol? I'm genuinely trying to figure
this out myself, but basically everything I read is beyond my scope of
competence and confuses me more. I'm learning the syntax of SQL well
enough, but I'm so confused about everything on the most fundamental
level.
By the way "SQL Server" is Microsoft's SQL flavor, just another one. Don't be confused with the concept of having some SQL server configured.
Yes, you can think of PostgreSQL as a language too, which shares most of its syntax and semantics with other SQL vendors. Yes, there is a 'basic' SQL language shared and compatible between all vendors; some share more aspects than others. In terms of Venn diagrams, you can think of many circles representing each one, Microsoft's SQL Server, Oracle SQL, PostgreSQL, MySQL, etc. sharing the very most of its elements, where each element is a SQL instruction.
When dealing with Databases in general, keep in mind that they helps to modelate situations of 'real world' scenarios or software systems. SQL allows to 'talk' to implementation of "Relational Databases" wich is one kind of database modeling, but there are others too. ER Diagrams helps to represent the 'structure' of a database in a conceptual manner. I like DBeaver because it has an integrated ER diagram generator wich helps to understand the structure of a given database instance.
I have used Postgres and it is an excellent product (and free).
I would install it standalone first. It does come with its own client tools, which you use to communicate with the database server, which runs independently as a service. However, you might be better off installing something like SqlWorkbench as a client tool (which I use). In the config you specify the machine Postgres is running on (which can be your local computer for testing purposes) and the port to connect on. Essentially, the client sends your instructions to Postgres server and the server returns the resultsets associated with your instructions. The client also formats the resultsets into a nice readable "spreadsheet" format with rows and columns.
First I'll try to answer the questions you asked. There is a SQL language, but in practice it is not strictly standardized. There are many offerings for databases and database servers. Many of these are discussed below.
Any database you pick will give you the chance to learn basics of SQL queries and this knowledge will serve you well even if you switch to a different database later.
Specifically, when it comes to PostgreSQL, it is a Relational Database Management System. It is a software that operates as a server. You can install it on your personal computer running Windows, Linux, or MacOS. You can also install in on a dedicated server computer where you'll get better performance and uptime. Further, there are many companies that offer PostgreSQL hosting including Amazon RDS and Google Cloud but they're not free.
For a CS student, PostreSQL installed on your personal computer might be a reasonable choice. But you have lots of options. Read on....
For a CS program, your choice of database will depend on:
what degree of portability you need
how much data you have
how many users will connect to database
what kinds of jobs you might pursue after graduation
Portability
If you think you want to ship your database with your application, then your best bet is probably SQLite. By some accounts it can handle several million rows worth of data and still be performant. However, it's not great if you need for multiple users to connect to the same database. Your data can get corrupted in many multi-user scenarios.
How Much Data and Users
For large data and large users, you'll want to consider the client/server heavy hitters:
PostgreSQL
MySQL/MariaDB
Oracle
SQL Server
These databases will support large quantities of data any many simultaneous connections. But if you want to distribute the database with your application, it's not a good idea. Or if you want to demonstrate your app, you need to ensure that a connection to a server will be available. All of these databases come with a free version, but the last two will have the most restrictions.
After Graduation
Now you're looking to the future and possibly what kind of skills you want to put on your resume. If you think you'll end up in a corporate environment that is already well established, they will likely already have a preferred database and it could be any of the ones listed here (SQLite or the "heavy hitters"). If you want to position yourself as developing apps with low overhead cost, you'll gravitate towards SQLite/PostgreSQL/MySQL. If you think you're going to be some kind of database administrator working in a buttoned-up corporate environment, those companies tend to favor SQL Server and Oracle.
Good luck. Any choice you make will probably be fine. Knowing some flavor of SQL is useful for your future endeavors.
SQL is a language like any other language but working on database. It is called SQL because it works on structured data like table (i.e rows and columns). After reading the documentation of PostgreSQL, I think we do not need any separate server installation. You can download it from here. If you are facing any issues with it I suggest using MySQL workbench. Although installation may take longer time, but its easy to understand.
The dev tools for SQL in Visual Studio are great.
Is it possible to develop an app for Microsoft SQL Server, and then deploy a MySQL-compatible database instead?
The dev tools for Microsoft SQL Server are really nice (i.e. LINQ support), but a MySQL-compatible column database has better performance for huge datasets.
You would need to use MySql .net connector
http://dev.mysql.com/doc/refman/5.1/en/connector-net.html
With this, you get some of the functionality that you have with SQL server (entity framework, designer, etc) there are still a bunch of things that are not supported, but it's a good start
It's possible, but a number of specifics might tend to prevent a full implementation on SQL Server, particularly with respect to stored procedures.
However, if the intent is to build a scaffolding on VisStudio and finish the development using the MySQL tools, it would work okay. You'll have to learn both SQLs quite thoroughly. The sooner you do that, the less grief there will be in the conversion.
One method for doing this would be to abstract away the database itself. That be done at least a couple of ways; the first way, you could use classes to build the SQL that your application requires, and then just use that; then all that has to happen is that it has to know how to generate the right SQL for the right server. One of the drawbacks of doing it that way, though, is that if you depend on functionality that exists on only one DBMS, you'll have to emulate it in that abstraction layer.
The other method that you could use is to create two versions of your classes that talk to the RDBMS, one for MySQL and one for Microsoft's SQL Server. Use an interface and derive from it in order to do the actual implementation. Of course, you'll want to make sure that the only responsibility of the class is to interact with the database, so if you're doing this for business layer objects, you'll be implementing those sorts of things with two classes: a low-level one for the database API, and a high-level one for actually providing the API that your application is going to consume.
Perhaps not a direct answer to your question, but the dblinq project may be of use to you.
It may be worth a look just to see the MySQL implementations within the project in order to determine what the real differences between SQL Server and MySQL are going to be and how they're going to affect you. The more you can abstract out those differences behind a dependency implementation, the easier it'll be to swap out one implementation for another.
You can write your code for SQL Server and then switch to Devart LinqConnect.
For example, you can create a LINQ to SQL model using Entity Developer (in VS integration mode or in standalone mode), then change the connection to the MySQL-specific one and run Update Database from Model wizard (don't forget to select the Regenerate Storage check box).
As a result, you will obtain a MySQL database, having structure identical to the SQL Server one.
i remember in my previous job, i needed to do data migration. in that case, i needed to migrate to a new system, i was to develop, so it has a different table schema. i think 1st, i should know:
in general, how is data migrated (with the same schema) to a different DB engine. eg. MySQL -> MSSQL. in my case, my destination DB was MySQL and i used MySQL Migration Toolkit
i am thinking, in an enterprise app, there may be stored procedures, triggers that also need to be imported.
if table schema is different, how will i then go abt doing this? in my prev job, what i did was import data (in my case, from Access) into my destination (MySQL) leaving table structures. then use SQL to select data and manipulate as required into final destination tables.
in my case, where i dont have documentation for the old db, and the columns was not named correctly, eg. it uses say 'field1', 'field2' etc. i needed to trace from the application code what the columns mean. any better way? or sometimes, columns contain multiple values in delimited data, is reading code the only way?
I really depends, but from your question I assume you want to hear what other people do.
So here is what I do in my current project.
I have to migrate from Oracle to Oracle but to a completely different schema.
The old system was 2-tier (old client, old database) the new system is 3-tier (new client, business logic, new database). We have more than 600 tables in the new schema.
After much pondering we scraped the idea of doing a migration from old database to new database in SQL. We decided that in our case i would be much easier to go:
old database -> old client -> business logic -> new database
In the old database much of the data is stored in strange ways and the old client
mangles it in complex ways. We have access to the source code of the old client but it is a very large system.
We wrote a migration tool that sits above the old client and the business logic.
We have some SQL before and some SQL after that but the bulk of data is migrated via
old client and business logic.
The downside is that it is slow, a complete migration taking more than 190 hours in our case but otherwise it works well.
UPDATE
As far as stored procedures and triggers are concerned:
Even as we use the same DBMS in old and new system (both Oracle) the procedures and
triggers are written from scratch for the new system.
When I've performed database migrations, I've used the application instead a general tool to migrate the database. The application connects to two databases and copies objects from one to the other. You don't have to worry about schema or permissions or whatnot since all that is handled in the application, just like what happens when you set up the application in the first place.
Of course, this may not help you if your application doesn't support this. But if you're writing an application, I strongly recommend doing it this way.
I recommend the wikipedia article for a good overview and links to the main commercial tools (and some non-commercial ones). Stored procedures (and kin, e.g. user-defined function), if abundant, are going to be the "hot spots" in the migration, requiring rare abd costly human skills -- as soon as you get away from the "declarative" mood of mainstream SQL, and into procedural code, you cannot expect automated tools to do a decent job (Turing's Theorem says that they actually can't, in a sufficiently general case;-). So, you need engineers with a good understanding of the procedural trappings of BOTH engines -- the one you're migrating from, the one you're migrating to. You can buy that -- it's one of the niches where consultants make REALLY good money!-)
If you are using MS SQL Server, you can use SSMS to script out the schema and all data in one go: SQL Server 2008: Script Data as Inserts.
If you are not using any/many non-standard SQL constructs, then you might be able to manually edit this scipt without too much effort.
I'm writing an app in vb.net and was wondering wath the best way to store/retrieve data was?
SQLite is a good choice.
I too use sql server to manage data for my desktop applicaton if it has to manage a large set of records.
But if an application is small then you can use ms-access or mysql as these database engine are light weight.
Try to use stored procedures as they can make ur execution faster
I would recommend the use of a relational database management system (and since you are using VB.NET, Microsoft SQL Server is probably going to be your best choice).
If a full-blown RDBMS is overkill for your application then you may want to read up on application settings.
It really depends on how much data you want to store. Little data could easily be stored in an XML based configuration file. If you have a lot of data to store, then XML will probably not provide the best performance. The more data you want to store, the more I would direct you to a database.
As for which database, it depends on how much data you want to store, how much work you want to do during installation, and how much control you have over the client's system. SQL Server or MySQL are good large databases, but if this is a small application, they might be overkill. Microsoft has a version of the SQL Server database that is file based (like MS Access). It doesn't allow stored procedures, but it can be embedded within your application (and its free). Its called SQL CE (Compact Edition).
SQLLite is good also, and you'll find a good amount of information to help you with that.
Just off the top, based on what you wrote and the wording, I would guess that you need something small, and quick. I would probably look at MS Access. There are ways you can use it without actually requiring that the user has access installed, its simple to setup, and the database is all in a single file, so installation is VERY easy.
Let me know how this works out for you,
Gabriel
If you just need to store simple configuration files, using the My.Settings namespace is a good way to go. Its very easy to use, and easy to access the data.
When developing whether its Web or Desktop at which point should a developer switch from SQLite, MySQL, MS SQL, etc
It depends on what you are doing. You might switch if:
You need more scalability or better performance - say from SQLite to SQL Server or Oracle.
You need access to more specific datatypes.
You need to support a customer that only runs a particular database.
You need better DBA tools.
Your application is using a different platform where your database no longer runs, or it's libraries do not run.
You have the ability/time/budget to actually make the change. Depending on the situation, the migration could be a bigger project than everything in the project up to that point. Migrations like these are great places to introduce inconsistencies, or to lose data, so a lot of care is required.
There are many more reasons for switching and it all depends on your requirements and the attributes of the databases.
You should switch databases at milestone 2.3433, 3ps prior to the left branch of dendrite 8,151,215.
You should switch databases when you have a reason to do so, would be my advice. If your existing database is performing to your expectations, supports the load that is being placed on it by your production systems, has the features you require in your applications and you aren't bored with it, why change? However, if you find your application isn't scaling, or you are designing an application that has high load or scalability requirements and your research tells you your current database platform is weak in that area, or, as was already mentioned, you need some spatial analysis or feature that a particular database has, well there you go.
Another consideration might be taking up the use of a database agnostic ORM tool that can allow you to experiment freely with different database platforms with a simple configuration setting. That was the trigger for us to consider trying out something new in the DB department. If our application can handle any DB the ORM can handle, why pay licensing fees on a commercial database when an open source DB works just as well for the levels of performance we require?
The bottom line, though, is that with databases or any other technology, I think there are no "business rules" that will tell you when it is time to switch - your scenario will tell you it is time to switch because something in your solution won't be quite right, and if you aren't at that point, no need to change.
BrianLy hit the nail on the head, but I'd also add that you may end up using different databases at different levels of development. It's not uncommon for developers to use SQLite on their workstation when they're coding against their personal development server, and then have the staging and/or production sites using a different database tool.
Of course, if you're using extensions or capabilities specific to a certain database tool (say, PostGIS in PostGreSQL), then obviously that wouldn't work.