How to tell Oracle to use more than one byte per character

When you create a table, by default, the number of bytes used to represent a character in a VARCHAR2 type is 1, irrespective of the character set of the DB. This may be fine if the character set is such that it uses just one byte per character. However, if the character set of the DB is such that it might take more than one byte to represent a character (for example, with character set = AL32UTF8) you might run into trouble, such as the error: ORA-01401: inserted value too large for column. However, when creating the table, you can specify that the column size is expressed in characters rather than bytes. For example:

CREATE TABLE test (col_test VARCHAR2(10 CHAR))

The previous code creates a table with just one column. The column will be able to contain 10 characters irrespective of the number of bytes used to represent the characters internally.