无效的数据类型 PL SQL (Oracle)

Question

Why am I getting following errors with this query?

-- NOT NULL
  ALTER TABLE employee
  MODIFY FirstName NOT NULL;

Error starting at line : 23 in command - ALTER TABLE employee MODIFY FirstName (NOT NULL) Error report - SQL Error: ORA-00902: invalid datatype 00902. 00000 - "invalid datatype" *Cause:
*Action: Table EMPLOYEE altered.

Answer 1

Wrong syntax. Remove brackets.

SQL> create table employee (first_name varchar2(10));

Table created.

SQL> alter table employee modify first_name not null;

Table altered.

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