Difference between varchar and varchar2 data types

VARCHAR and VARCHAR2 are both data types in Oracle that are used to store character strings. Here are the differences between them:

1. VARCHAR can store up to 2000 bytes of characters while VARCHAR2 can store up to 4000 bytes of characters.

2. In VARCHAR, the trailing spaces are preserved. For example, if you store 'abc ' in a VARCHAR column, it will preserve the space at the end. But in VARCHAR2, the trailing spaces are not preserved. For example, if you store 'abc ' in a VARCHAR2 column, it will not preserve the space at the end.

3. VARCHAR is an ANSI standard data type but VARCHAR2 is a data type that is specific to Oracle.

4. Oracle recommends using VARCHAR2 instead of VARCHAR, because in future versions of Oracle, VARCHAR might be defined as a separate data type that is not 100% compatible with VARCHAR2.

5. The VARCHAR data type is currently synonymous with the VARCHAR2 data type and is reserved for future use.

6. The semantics of VARCHAR change to match those of VARCHAR2 when the compatibility level of the database is set to 10.1 or higher.

7. The VARCHAR data type will not undergo semantic changes in future releases, and therefore code that uses the VARCHAR data type is less likely to require changes in future releases.

In conclusion, while both VARCHAR and VARCHAR2 are used to store character strings, they have different properties and VARCHAR2 is generally recommended for use in Oracle.