Question

Hope someone can help me out with this one !

I have a sql file that looks like this:

CREATE TABLE IF NOT EXISTS users(
    id INT UNSIGNED NOT NULL AUTO_INCREMENT,
    firstname VARCHAR(30) NOT NULL,
    lastname VARCHAR(30) NOT NULL,

    PRIMARY KEY (id),
    CONSTRAINT UNIQUE (firstname,lastname)
)
ENGINE=InnoDB
;

INSERT IGNORE INTO users (firstname,lastname) VALUES ('x','y');
/*
INSERT IGNORE INTO users (firstname,lastname) VALUES ('a','b');
*/

I have buit a web application that initializes a mysql database at startup with this function:

public static void initDatabase(ConnectionPool pool, File sqlFile){
    Connection con = null;
    Statement st = null;
    String mySb=null;
    try{
        con = pool.getConnection();
        mySb=IOUtils.copyToString(sqlFile);

        // We use ";" as a delimiter for each request then we are sure to have well formed statements
        String[] inst = mySb.split(";");

        st = con.createStatement();

        for(int i = 0; i<inst.length; i++){
            // we ensure that there is no spaces before or after the request string
            // in order not to execute empty statements
            if(!inst[i].trim().isEmpty()){
                st.executeUpdate(inst[i]);
            }
        }
        st.close();
    }catch(IOException e){
        throw new RuntimeException(e);
    }catch(SQLException e){
        throw new RuntimeException(e);
    }finally{
        SQLUtils.safeClose(st);
        pool.close(con);
    }
}

(This function was found on the web. Author, please forgive me for not citing your name, I lost it !!)

It works perfectly as long as there is not SQL comment blocks.

The copyToString() function basically does what it says.
What I would like now is build a regex that will remove block comments from the string. I only have block comments /* */ in the file, no --.

What I have tried so far:

mySb = mySb.replaceAll("/\\*.*\\*/", "");

Unfortunatly, I’m not very good at regex…

I get all the troubles of “The matched string look something like /* comment */ real statement /* another comment*/ ” and so on…

Answer 1

Try

mySb = mySb.replaceAll("/\\*.*?\\*/", "");

(notice the ? which stands for “lazy“).

EDIT: To cover multiline comments, use this approach:

Pattern commentPattern = Pattern.compile("/\\*.*?\\*/", Pattern.DOTALL);
mySb = commentPattern.matcher(mySb).replaceAll("");

Hope this works for you.