Regex - SQL statement

Question

It is only a very simple SQL parsing process, no HAVING, ORDER BY or GROUP BY would be in the statement that needs to be parsed, but something about matching an asterisk in SELECT part won't work (e.g. SELECT * .......)

Here's the code part:

String span="SELECT * FROM table1 t, table2";

span=span.toUpperCase();

System.out.println(span);

// Segments
String column="(\\w+\\s*(\\w+\\s*){0,1})";

String columns=column+"(,\\s*"+column+")*";

String ownerenable="((\\w+\\.){0,1}\\w+\\s*(\\w+\\s*){0,1})";

String ownerenables=ownerenable+"(,\\s*"+ownerenable+")*";

String from="FROM\\s+"+columns;

String condition="(\\w+\\.){0,1}\\w+\\s*(=|<|>|LIKE|IS)\\s*'?(\\w+\\.){0,1}[\\w%]+'?";

String conditions=condition+"(\\s+(AND|OR)\\s*"+condition+"\\s*)*";

String where="(WHERE\\s+"+conditions+"){0,1}";

String pattern = "SELECT\\s+(\\*|" + ownerenables + "\\s+" + from + ")\\s+" + where + "\\s*" + "(;){0,1}";

System.out.println(pattern);
System.out.println(span.matches(pattern));

Now if I set span to something like

"SELECT t.id, product p FROM table1 t, table2 WHERE t.id=10;"

The match result would be true

================================

But if I set it to something like this:

"SELECT * FROM table1 t, table2 WHERE t.id=10;"

(It's an asterisk I'm using for the SELECT)

It won't work in this case

Am I doing anything wrong about that asterisk?

Answer 1

The parenthesis must be closed before the from:

String pattern = "SELECT\\s+(\\*|" + ownerenables + ")\\s+" + from + "\\s+" + where + "\\s*" + "(;){0,1}";

Answer 2

you select table2 but don't select anything from it. you must specify the join between table1 and table2 if you want to do an * select.

This is your issue.