Varchar2(s) is used to define a variable length character of maximum size s.
Nvarchar2: Same as VARCHAR2 except that the column stores values in the National CS ie you can store values in Bangla if your National CS is BN8BSCII .If the National CS is of fixed width CS (all characters are represented by a fixed byte say 2 bytes for JA16EUCFIXED) then NVARCHAR2(30) stores 30 Characters.
If the National CS is of variable width CS (some characters are represented by 1 byte some by 2 bytes as in UTF8 ) then NVARCHAR2(30) stores 30 bytes.no diff between varchar and varchar2 char store only chacter type but varchar2 store variable chacters. also varchar2 shirinks the space if not fully filled but char cant.
The difference between varchar and nvarchardatatypes is that Nvarchar stores UNICODE data. If you have requirements to store UNICODE or multilingual data, nvarcharis your choice. Varchar stores ASCII data and should be your data type of choice for normal use.
create table EMP( E_NAME VARCHAR2(10) E_LOC VARCHAR2(10) E_SAL NUMBER(5.2) E_DEPT VARCHAR2(10));
12,500 is the maximum length of a varchar field. The nVarchar field has the same limitation however you will use twice the data store space with an nVarchar as it is effectively the same as a varchar with the exception that it will store data required for international character sets. If you support a multi-language system then you will want to use a nVarchar character type for these fields.
Datatype represents the type of data like integer, varchar2 etc. Example name varchar2(20) it denotes that name is an attribute of character and size is 20 characters .
CREATE TABLE EMPLOYEE (EMP_ID NUMBER(10) PRIMARY KEY,NAME VARCHAR2(100),EMAIL_ID VARCHAR2(50) UNIQUE);Hope it helped.SP.
The syntax for dynamic sql is For example if you want to create table at run time then syntax is Declare V-string varchar2(900); begin V_string:='create table ORACLE (empno number,ename varchar2(90)'); execute immediate V_string; end; /
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