I have believed for a while that a varchar2(1) would have included a 'length byte',
making it more wasteful of storage than a char(1) but in fact the two are strictly
identical storage-wise :
SQL> create table t(c1 char(1),
2 c2 varchar2(1));
Table created.
SQL> insert into t values('A', 'B');
1 row created.
SQL> select vsize(c1), dump(c1), vsize(c2), dump(c2)
2 from T;
VSIZE(C1)
----------
DUMP(C1)
--------------------------------------------------------------------------------
VSIZE(C2)
----------
DUMP(C2)
--------------------------------------------------------------------------------
1
Typ=96 Len=1: 65
1
Typ=1 Len=1: 66
SQL>
That said, for the sake of logic I still prefer using CHAR instead of VARCHAR when the
length doesn't vary at all - call it autodocumentation. VARCHAR2(1) columns -
especially when NOT NULL - are unlikely to vary much in length.
SF
>----- ------- Original Message ------- -----
>From: "Stephane Paquette"
><[EMAIL PROTECTED]>
>To: Multiple recipients of list ORACLE-L
><[EMAIL PROTECTED]>
>Sent: Fri, 31 Oct 2003 08:04:27
>
>Hi,
>
>Some people here are telling me that using char(1)
>is better than
>varchar2(1) for a field code.
>I do not see why.
>
>I never used char as it may cause problems when
>doing some comparisons.
>
>Any reasons ?
>
>
>Stephane Paquette
>Administrateur de bases de donnees
>Database Administrator
>Standard Life
>www.standardlife.ca
>Tel. (514) 499-7999 7470 and (514) 925-7187
>[EMAIL PROTECTED]
><mailto:[EMAIL PROTECTED]>
>
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