Escaping string literal "by", sql reserved word, while creating java Query object

Question

The following code is throwing exception because string field has the SQL reserved word "by" in it. How would I escape this reserved word. The code is meant for google datastore.

String field="Hosted by me"
PersistenceManager pm=PMF.get().getPersistenceManager();
    try{
    Query query=pm.newQuery("select from "+SomeObject.class.getName()
            +" where mField=='"+field+"'");
    _logger.info(query.toString());
    SomeObject=query.execute();
    }finally{
        pm.close();
    }

Here is the exception: : org.datanucleus.exceptions.NucleusUserException: Query contains a JDOQL keyword ("by") that is out of order. Keywords can only be used in a defined order.

Your column name is "Hosted by me"? I would put underscore separators between the words. — I82Much, Oct 15 '11 at 21:42

score 2 · Accepted Answer · answered Oct 15 '11 at 22:13

2

Try this:

PersistenceManager pm = ...;
try {
  Query quer = pm.newQuery("select from " + SomeObject.class.getName()
                          " where mField == mFieldParam" +
                          " parameters String mFieldParam");
  List<SomeObject> results = (List<SomeObject>) query.execute("Hosted by me");
} finally {
  ...
}

answered Oct 15 '11 at 22:13

Dilum Ranatunga

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Dilum Thanks! I won't be able to figure it out even if I read the javadoc http://db.apache.org/jdo/api20/apidocs/javax/jdo/PersistenceManager.html#newQuery(java.lang.String) . I would appreciate if you can give me pointers on where I can go read a bit more of this usage explained in human terms. – Win Myo Htet Oct 16 '11 at 00:01
Yes, the apache docs are quite poor. The javadocs are atrocious. Look at Google's own docs with GAE. Start wih this: http://code.google.com/appengine/docs/java/datastore/jdo/queries.html – Dilum Ranatunga Oct 16 '11 at 07:15

Escaping string literal "by", sql reserved word, while creating java Query object

1 Answers1