ColumnNamesFinder

[Nobody/Anonymous]

Hi I want to find the Column Names[and their respective] in a SQL query just like the Table names,
The query can be complex, I mean involve sub queries etc...
Just like
SELECT * FROM MY_TABLE1, MY_TABLE2, (SELECT * FROM MY_TABLE3) LEFT OUTER JOIN MY_TABLE4 "+
        " WHERE ID = (SELECT MAX(ID) FROM MY_TABLE5) AND ID2 IN (SELECT * FROM MY_TABLE6)

I am sorry for asking this, I am new to Java and dunno the Visitor Design pattern,
any help would be appreciated.

Thank you,
Ashwin.

[Nobody/Anonymous]

I forgot to mention that I need to get the column in the Group by, Order by or having clauses too.

--
Ashwin

[Leonardo Francalanci]

Have a look at src\net\sf\jsqlparser\util\deparser\ExpressionDeParser.java.

Every column should pass through:

public void visit(Column tableColumn)

You can do whatever you want with tableColumn (for example putting that in a vector).
You should:

1) extend ExpressionDeParser.java -> MyExpressionDeParser.java extends ExpressionDeParser.java
2) pass it to the select deparser:

StringBuffer buffer = new StringBuffer();
CCJSqlParserManager parserManager = new CCJSqlParserManager();
String statement = "SELECT * FROM mytable WHERE mytable.col = 9 LIMIT 3, ?";
Select select = (Select) parserManager.parse(new StringReader(statement));
SelectDeParser selectDeParser = new SelectDeParser();
selectDeParser.setBuffer(buffer);
MyExpressionDeParser expressionDeParser = new MyExpressionDeParser(selectDeParser, buffer);
selectDeParser.setExpressionVisitor(expressionDeParser);
select.getSelectBody().accept(selectDeParser);

3) your MyExpressionDeParser.visit(Column tableColumn) method should be called for each column in the where clause

[Nir Peterson]

Is there any other method other then implementing Visior to get list of all columns from expression. I am trying to parse sql function. e.g. sum(t1.amount)/count(t1.name) and get all column names. i.e. {"t1.amount", "t1.name"} Thanks