Implementing File Based Database system in java

[Prateek Sharma]

Hello All,

I am going to create own File based database system.(In this we use flat .txt files to store our data.)

Please tell me how can I verify my query in java against the sysntax.
Currently I am thinking to use regular expression for queries to be verified but its is too hard to write the regular expression for all queries. Please tell me another way to do this or provide me the regular expression for queries if its possible.

Thanks in advance.

[Paul Sturrock]

ANTLR will no doubt parse SQL. You should look at this rather than reinventing the wheel with reqular expressions.

I don't know your driver for this requirement, but databases are complex beasts. If I were writing this my area of concern would be how to implement transactional behaviour properly in a concurrent environment. Parsing SQL queries is a far easrier job than that. Would it not be safer to just use an existing relational database?

[Prateek Sharma]

Hi Paul,

Thanks for reply,
But can you please tell me java based way to verify SQL query syntax.

[Tamas Jano]

Hi Prateek,

I won't question why are you doing it only what kind of queries do you want to parse?

I would suggest to take a look at some frameworks' source code and check the implementation of their parsers. (eg. Hibernate, Lucene).
There are also a lot of data parser plug-ins for eclipse and you could take a look at their implementation.
http://www.eclipse.org/datatools/project_sqldevtools/sqltools_doc/SQL%20Query%20Parser%20User%20documentation.htm
http://lucene.apache.org/java/docs/queryparsersyntax.html

Good luck!
T

[Paul Sturrock]

But can you please tell me java based way to verify SQL query syntax

Please see my earlier post. There is a link to a Java based way to verify query syntax.

[Ulf Dittmer]

In addition to using a parser (like Antlr, SableCC or JavaCC) you might check out what the eminent Java DBs are doing. Specifically HSQLDB and Derby are open source; it shouldn't be too hard to find out what they do and how they do it. License permitting, you might even be able to lift some code from them. (Of course, as Paul said, you could just use these DBs to begin with.)

[Bill Shirley]

You might want to check out this java wrapper of sqlite3.

I'm using sqlite3 in a non-java project, and it's quite handy.



Implementing my own database is further down the list of fun programming things to do than implementing my own language parser. If it's been done before, and done well then beg/borrow/steal it.

[Jimmy Clark]

Build your own parser for the database. Purchase a copy of

Building Parsers With Java
by Steven John Metsker
Publisher: Addison-Wesley Professional
Language: English
ISBN-10: 0201719622

The book also comes with a CD that has the source code for building a parser. If you read the book, you will know how to modify the code for your needs.

Aside, you should build the database so that data is stored in XML files, i.e. .xml