Oracle - select * where column>5
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I am trying to do a comparison based on a column. Let's say, if column>5.  

    select * where column>5

The column contains non digits. I thought Oracle allows one to compare strings (like Java).

Apparently this is not allowed.  

    ORA-01722: invalid number
    01722. 00000 -  "invalid number"

Is there a way to do comparisons with non numeric fields?  
Thanks