Assigning an empty string to the character variable is exactly the same as assigning NULL to it. : CHAR « PL SQL Data Types « Oracle PL/SQL Tutorial






  1. Oracle PL/SQL Tutorial
  2. PL SQL Data Types
  3. CHAR
SQL>
SQL> declare
  2       v_text CHAR(1) :=''; -- the same as NULL
  3  begin
  4     NULL;
  5  End;
  6  /

PL/SQL procedure successfully completed.

SQL>
SQL>








21.2.CHAR
21.2.1.CHAR
21.2.2.CHAR type variable
21.2.3.Compare CHAR and VARVHAR32 variables for equality
21.2.4.Constants are compared using blank-padded comparison semantics, so the trailing spaces won't affect the result.
21.2.5.Fixed length strings are compared with blank-padded comparison semantic
21.2.6.Compare fixed length string and a literal
21.2.7.Compare char against varchar, and the trailing spaces do matter.
21.2.8.Assigning an empty string to the character variable is exactly the same as assigning NULL to it.