Difference between VARCHAR, VARCHAR2 and CHAR data types in Oracle.

Both CHAR and VARCHAR2 types are used to store character string values, however, they behave very differently. The VARCHAR type should not be used:

=> CHAR:
 
CHAR should be used for storing fixed length character strings. String values will be space/blank padded before stored on disk. If this type is used to store variable length strings, it will waste a lot of disk space.

SQL> CREATE TABLE char_test (col1 CHAR(10));

Table created.

SQL> INSERT INTO char_test VALUES ('qwerty');

1 row created.

SQL> SELECT col1, length(col1), dump(col1) "ASCII Dump" FROM char_test;

COL1       LENGTH(COL1) ASCII Dump

---------- ------------ ------------------------------------------------------------

qwerty               10 Typ=96 Len=10: 113,119,101,114,116,121,32,32,32,32

Note: ASCII character 32 is a blank space. 

=> VARCHAR:
 
Currently VARCHAR behaves exactly the same as VARCHAR2. However, this type should not be used as it is reserved for future usage.

SQL> CREATE TABLE varchar_test (col1 VARCHAR2(10));

Table created.

SQL> INSERT INTO varchar_test VALUES ('qwerty');

1 row created.

SQL> SELECT col1, length(col1), dump(col1) "ASCII Dump" FROM varchar_test;

COL1       LENGTH(COL1) ASCII Dump

---------- ------------ ------------------------------------------------------------

qwerty                6 Typ=1 Len=6: 113,119,101,114,116,121

=> VARCHAR2:
 
VARCHAR2 is used to store variable length character strings. The string value's length will be stored on disk with the value itself.

SQL> CREATE TABLE varchar2_test (col1 VARCHAR2(10));

Table created.

SQL> INSERT INTO varchar2_test VALUES ('qwerty');

1 row created.

SQL> SELECT col1, length(col1), dump(col1) "ASCII Dump" FROM varchar2_test;

COL1       LENGTH(COL1) ASCII Dump

---------- ------------ ------------------------------------------------------------

qwerty                6 Typ=1 Len=6: 113,119,101,114,116,121

Feel Free to Comment.                        Shabbir Ahmad (SE)