Can CHAR/VARCHAR store strings with nul (ASCII 0) in them? It seems it
can't. [I've used CHAR(2), VARCHAR(2), CHAR(2) BINARY, VARCHAR(2) BINARY].
=======================================================================
create table t1 (
id int not null primary key,
code varchar(2) not null, unique(code));
insert into t1 values (1,'');
insert into t1 values (2,char(0));
insert into t1 values (3,char(32));
insert into t1 values (4,concat(char(0),char(0)));
insert into t1 values (5,concat(char(0),char(32)));
insert into t1 values (6,concat(char(32),char(0)));
insert into t1 values (7,concat(char(32),char(32)));
select
id,
length(code),
if(length(code)=0,
'',
if(length(code)=1,
ord(code),
concat(ord(substring(code,1,1)),' ',ord(substring(code,2,1)))
)
) as code
from t1;
=======================================================================
Record 3, 5, and 7 is rejected due to duplicate value.
+----+--------------+------+
| id | length(code) | code |
+----+--------------+------+
| 1 | 0 | |
| 2 | 1 | 0 |
| 4 | 2 | 0 0 |
| 6 | 2 | 32 0 |
+----+--------------+------+
4 rows in set (0.00 sec)
It seems the string in CHAR/VARCHAR is stored as null-terminated ala C.
But why is record 3 rejected too?
If I want to store 128-bit MD5 hash as a primary key, what would be the
most compact way of storing them?
--
dave
