ORACLE TRIM function -


suppose column defined as:

col varchar2(5)
  • if col='x' true;
  • if trim(col)=trim('x') true;
  • but if col contains ' ', if trim(col)=trim(' ') false;

why?

thanks

oracle doesn't support empty strings ''; oracle uses null instead (whenever result should empty string you'll null in fact). since

  null = null -- <- null (and not true)

your formula 

  trim(col) = trim(' ') -- <- equals "null = null"

is null (and not true) too


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