Zql: a Java SQL parser

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What is Zql ?

Zql is a SQL parser written in Java.
Zql parses SQL and fills in java structures representing SQL statements and expressions.

Zql can parse all the queries given as examples in the following (downloaded from ).

See the Zql API documentation for more info about the Zql structures.

A SQL expression evaluator comes with Zql, so you can easily evaluate SQL expressions out of the parser.

Warning: No warranty !

Zql is no commercial product: feel free to use it, but we provide no warranty.
Zql APIs may be subject to changes, to enrich functionalities or fix bugs.

for any bug report or suggestion.

How to use Zql ?

First of all,
Then:

• Unpack Zql.tar: tar xvf Zql.tar (or use WinZip if you are a Windows user).
• Make your CLASSPATH variable point on the Zql/classes directory.
• Type java Zql.ZqlParser, then some SQL statements (like select * from customer;) to make sure Zql is properly installed.
• Go in the Zql/demo directory, see the README file and the ZDemo.java program to discover how you can use Zql to write your own SQL application!

Note that java sources are NOT provided in the package, but you can concerning the availability, licensing terms and conditions.

More details

The parser itself is written with JavaCC, a Java parser generator (like Unix's popular yacc generator).

It takes as input SQL statements (select, insert, update, delete, commit, rollback, set transaction), and fills in Java structures that represent the statements it parsed.

Example:
SELECT ANTIQUEOWNERS.OWNERLASTNAME, ANTIQUEOWNERS.OWNERFIRSTNAME
FROM ANTIQUEOWNERS, ANTIQUES
WHERE ANTIQUES.BUYERID = ANTIQUEOWNERS.OWNERID AND ANTIQUES.ITEM = 'Chair';


Will result in a ZqlQuery structure.
ZqlQuery's getSelect(), getFrom() and getWhere() methods will extract the SELECT, FROM and WHERE parts of the query.

• getSelect() will return a Vector of ZSelectItem, data structures that give information about the columns and/or operations requested (including SQL expression support, like in SELECT a+b FROM num;).
  
• getFrom() will return a Vector of ZFromItem, data structures that give information about the tables involved in the query.
  
• getWhere() will return a SQL expression, a data structure that represents ANTIQUES.BUYERID = ANTIQUEOWNERS.OWNERID AND ANTIQUES.ITEM = 'Chair' in the example above (the expression evaluator that comes with Zql can evaluate such expressions, for a given data tuple).