Testing the Oracle to_date function

Question

I'm writing an integration test in Grails using GORM.

I want to do something like the following:

delete from Statistic 
where stat_date = TO_DATE(:month_year, 'MON-YYYY')

But I get the following error:

java.sql.SQLException: Unexpected token: TO_DATE in statement [delete from statistics where stat_date=TO_DATE(?, 'MON-YYYY')]

I think the error is caused by the in memory database used by GORM (is it H2?) not supporting the to_date function.

Any ideas on how to write the delete SQL so that it works in a test and in live?

As I only really care about the Month and Year one thought I had would be to delete the records where the stat_date is between the first and last date of the given month.

Can any one think of a better way?

Answer 1

Yes, H2 doesn't support TO_DATE, it's in 1.4.x roadmap. Instead you can use the EXTRACT function that exists both in Oracle DB and H2.

Answer 2

This still comes up as number 1 on google searches so here's what worked for me.

My unit tests/local environment build and populate a schema using sql files. I created the following alias in the sql file

-- TO_DATE 
drop ALIAS if exists TO_DATE; 
CREATE ALIAS TO_DATE as '
import java.text.*;
@CODE
java.util.Date toDate(String s, String dateFormat) throws Exception { 
  return new SimpleDateFormat(dateFormat).parse(s); 
} 
';

Notice the use of single quotes instead of $$ in h2 user defined functions as that is the only format that worked for me.

Answer 3

I had to adjust bluesman's answer in order to make it work for the date formats that are commonly used in our Oracle sql.

This version supports dateFormats like 'DD-MON-YYYY'

-- TO_DATE
drop ALIAS if exists TO_DATE;
CREATE ALIAS TO_DATE as '
import java.text.*;
@CODE
java.util.Date toDate(String s, String dateFormat) throws Exception {
  if (dateFormat.contains("MON")) {
      dateFormat = dateFormat.replace("MON", "MMM");
  }
  if (dateFormat.contains("Y")) {
      dateFormat = dateFormat.replaceAll("Y", "y");
  }
  if (dateFormat.contains("D")) {
      dateFormat = dateFormat.replaceAll("D", "d");
  }
  return new SimpleDateFormat(dateFormat).parse(s);
}
';

I found the tips on this blog post http://javatechniques.com/blog/dateformat-and-simpledateformat-examples/ helpful in figuring out how to translate the Oracle date formats into SimpleDateFormat's formats.

Answer 4

java.util.Date toDate(String dateTime, String dateFormat) throws Exception {
    if (dateFormat.contains("MON")) {
        dateFormat = dateFormat.replace("MON", "MMM");
    }
    if (dateFormat.contains("Y")) {
        dateFormat = dateFormat.replaceAll("Y", "y");
    }
    if (dateFormat.contains("D")) {
        dateFormat = dateFormat.replaceAll("D", "d");
    }
    if (dateFormat.contains("HH")) {
        dateFormat = dateFormat.replaceAll("HH", "hh");
    }
    if (dateFormat.contains("hh24")) {
        dateFormat = dateFormat.replaceAll("hh24", "hh");
    }
    if (dateFormat.contains("MI") || dateFormat.contains("mi")) {
        dateFormat = dateFormat.replaceAll("MI", "mi").replaceAll("mi", "mm");
    }
    if (dateFormat.contains("SS")) {
        dateFormat = dateFormat.replaceAll("SS", "ss");
    }
    return new SimpleDateFormat(dateFormat).parse(dateTime);
}

Answer 5

Or you can define your own TO_DATE like

    CREATE ALIAS TO_DATE AS $$
java.util.Date to_date(String value, String format) throws java.text.ParseException {

java.text.DateFormat dateFormat = new  java.text.SimpleDateFormat(format);
    return dateFormat.parse(value);
}
$$;

see http://www.h2database.com/html/features.html#user_defined_functions