Which datatypes use the National Character Set?

There are three datatypes which can store data in the national character set.

1)NCHAR: It is fixed length national character set- character datatype. This datatype uses CHAR length semantics, that is, the length of the NCHAR datatype column is defined in characters.

2)NVARCHAR2: It is variable length national character set- character datatype. This datatype uses CHAR length semantics, that is, the length of the NVARCHAR2 datatype column is defined in characters.

3)NCLOB: It stores national character set data up to four gigabytes. Data is always stored in UCS2 or AL16UTF16, even if the NLS_NCHAR_CHARACTERSET is UTF8.

If you use NCHAR/NVARCHAR2/NCLOB data type then, use the (N'...') syntax when coding these data type so that literals are denoted as being in the national character set by prefixing letter 'N'.

Below is an example.

SQL> create table t_test(col1 NVARCHAR2(30));

Table created.

SQL> insert into t_test values(N'This is NLS_NCHAR_CHARACTERSET');

1 row created.

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