Re: JDBC compare the content of two tables

Patricia Shanahan <>
Fri, 10 Aug 2007 06:01:29 -0700
If you only care about equal/unequal, not order, you might be able to
get away with checking the types and the getBytes result. If two columns
have the same type and the same getBytes result they have to be equal.


George3 wrote:

Thanks Patricia,

I think your method is of good architecture and extensible capability. But I
think I still need to write compare code for each type of columns, right?

Are there any ways to compare content in a unified way without different
coding for different column types? The two tables are of the same schema
(same column names and same column type).


Patricia Shanahan wrote:

I can understand that your method works. But I still need to implement
various comparison functions for each type of columns. Are there any way to
implement a comparison function independent of column type?

You have to write code for each type (or use some existing method),
but then polymorphism selects the correct method for you. You just
use the interface.

I felt that polymorphism does not help much here, because much of the
work of comparing a pair of columns is doing the extraction from RowSet
and field number to Java primitive or object.

For example, in my compare function for doubles:

  public int compare(RowSet row1, int field1,
    RowSet row2, int field2){
    double val1 = row1.getDouble(field1);
    double val2 = row2.getDouble(field2);

one third of the method body does the actual comparison, two thirds do


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