Reading some new functions on the mysql development documentation page, I come across what looks to be a gimmick and in my eyes provide no practical usage. The function in question is
show create table tablename
which outputs how the table is actually constructed.. So the question is, how would this be useful in an actual productio mode? a function which shows how the table is created?
Possible scenarios:
Assist in automation of deployments for some PHP packages which rely on a database? Just stick to importing a .sql document on running the installation?
Create a new table on the fly via php? That's somewhat-bad practice imho
understandably this can be boiled down to the common response with asking exec() questions within PHP or other languages.
if exec is your answer, you are asking the wrong questions
So the overall question, which might boil down to the above quote, is what practical usages will this show create table actually perform in a production state SQL Server?
as most production servers import a .sql document when an updated package is released, this minimizing possible conflicts from manually importing and not configuring a datatable correctly on the production server?
show create table is a convenient way to see column types, constraints, etc. It's helpful when trying to answer questions like "which fields on this table are indexed?" for example.
Related
I don't know completely what I want, but surely someone has had the same need, and has solved it in a far better manner than I could:
I'm looking for some mechanism to extract the data definition of a mySQL table from the database and allow it to be queried for the list of columns and their definitions, as part of a routine to dynamically construct DML? It would also be good to have the table parameters (e.g. ENGINE, INDEX, etc.) available, too.
Our databases aren't particularly advanced, and I certainly don't have an encyclopedic knowledge of SQL DDL, so what I came up with probably wouldn't be of much use to anyone else. Is there something already out there in Perl - preferably object-oriented - to do this, at least for mySQL?
Yes, there's a Perl package SQL::Translator, part of a toolset called SQLFairy. It parses SQL DDL from an SQL script or from a live database instance. It supports several RDBMS, including MySQL.
Then it offers tools to do schema conversions, schema diffs, and a bunch of other cool stuff.
http://metacpan.org/pod/SQL::Translator
http://sqlfairy.sourceforge.net/
I found the docs are better than most Perl projects, but still I had to read the code to understand how to use it in the way I wanted to.
The DBI interface has a set of "Catalog Methods": http://metacpan.org/pod/DBI#Catalog-Methods.
There is a similar StackOverflow question you can look at: How do I get schemas from Perl's DBI?
I am developing a web application in which a user can Create a table in data base. I am thinking on taking the attribute names and table description from user and put them into SQL query and execute it. But the drawback is that if this application is installed somewhere else all the db connection parameters have to be changed secondly it will be hard coded. Or is this the approach in software industry?
Another approach I can think of is taking all the information about creating a new table from user and inserting them into one table and have some kind of trigger on this table which creates a new table everytime when insertion is performed into the first table.What would be the SQL Script for such thing if my approach is correct?
I am using SPRING - MVC, Hibernate, MySQL, REST web service
Please correct me if I am thinking in wrong direction. TO be honest I am not clear on how I am going to do this.
Thanks
This is risky, since a database schema with a vague and ever-expanding schema will become difficult to manage. Your problem isn't how to manage the credentials, which you would have to handle securely whether users were creating tables or not. Your problem is why it seems necessary for users to create tables.
Are you building an interface to manage arbitrary databases? Maybe phpmyadmin would give your users everything they need.
Or are you doing something not quite so general purpose and open ended? Perhaps with a sufficiently rich table design, you can give the users what they want without requiring that they build their own tables. What information do users have to put in a table that it looks like they need to build their own?
If you are more specific with your objectives, we could be more helpful.
I recently inherited a website and they have a simple back-end area which was created using phpmaker. The back-end displays various MYSQL database tables.
There are two tables which hold registration information related to promotions/contests the company runs online. The client wants to begin archiving the registration data monthly, but still have the data accessible for future export or review.
So, can anyone tell me what the best approach would be to achieve this? I read about partitioning and Maatkit, but I'm not sure which - if either - would be a smart choice.
I would prefer to keep the table names the same because the table name is referenced in several instances within the PHP code running the promo/contest applications. I would also like for everything to be 'automatic' or at least executed at the click of a button; though I realize that might not be completely realistic.
I should note that I do not have the phpmaker project file and have been unable to obtain it.
Any help on this matter would be a great help.
MK-Archiver This is a good way to archive live mysql database tables
What MK- Archiver does is to archive rows from a table to another table and/or a file
I have lots of stuff in an app.config, and when changes are necessary, an app restart is required. Bad for my 24x7 web server system (it really is 24x7, not even 23x7). I would like to use a good strategy for keeping the config information in a DB table and query/use it as needed. I googled around a bit and am coming up dry. Does anyone have any suggestions before I re-invent the wheel?
Thanks.
I needed exactly this for my recent application, and couldn't use any application server specific techniques as I needed some console apps run on cronjobs to access them too.
I basically made a couple of small tables to create a registry-style configuration database. I have a table of keys (which all have parent-keys so they can be arranged in a tree structure) and a table of values which are attached to keys. All keys and values are named, so my access functions look like this:
openKey("/my_app");
createKey("basic_settings");
openKey("basic_settings");
createValue("log_directory","c:\logs");
getValue("/my_app/basic_settings","log_directory");
The tree structure allows you to logically separate similar data (e.g. you can have a "log_directory" value under several different keys) and avoids having the overly verbose names you find in properties files.
All the values are just strings (varchar2 in the db), so there's some overhead in converting booleans and numbers: but it's only config data, so who cares?
I also create a "settings_changed" value that has a datetime string in it: so any app can quickly tell if it needs to refresh it's configuration (you obviously need to remember to set it when you change anything though).
There may be tools out there to do this kind of thing already: but this was only a days worth of coding and works a treat. I added command line tools to edit and upload/download parts or all of the tree, then made a quick graphical editor in Java Swing.
I have a small amount of experience using SVN on my development projects, and I have just as little experience with relational databases. I know the basic concepts like tables, and SQL statements, but I'm far from being an expert.
What I'd like to know is if there are any generic version control type systems like SVN, but that work with a database rather than files. I would like the same kind of features you get with SVN like the ability to create branches, create tags, and merge branches together. Rather than a revision number being associated to a version of a file repository it would be associated with a version of the database.
Are their any generic solutions available that can add this kind of functionality independent of the actual database schema? I'd be interested in solutions that work with MySQL or MS SQL Server.
I should also clarify that I'm trying to version control the data not the schema. I would expect the schema to remain constant. So really it seems like I want a way to create a log of all the INSERT, UPDATE, and DELETE requests sent the the database between each version of the data. That way any version could be recreated by resending all the SQL statements that have been saved up to the desired version.
You can script all your DDL, stored procedures and such to regular text files.
Then you can simply use SVN for database versioning.
I've never found a solution that works as well as Subversion, but here's a few things I've done that have helped:
Make scripts that will create the schema and populate any initial data. Then make an update script for each change after that. It's a fairly manual process, but it works. There's extra things that help like storing the current version number in a table in the db and making sure that the scripts are idempotent.
Store the full development db in Subversion. This doesn't usually work out too well for me if there is a lot of data or it is frequently changed. But in some projects is could work.
I keep and maintain create scripts in my version control system.
There are two things I can think of:
http://www.liquibase.org/ - provides a way of generally managing database changes. Creates files that get committed into source control, and it helps manage changes across different development databases, etc.
http://www.viget.com/extend/backup-your-database-in-git/ - this describes a strategy for backing up a database into source control, but the same strategy can be used just on the schema. In this scheme, the database would be in a separate area from your main code. (This can be used with other source control systems too.)