Home » Oracle » 1z0-061 v.2 » Which create table statement is valid?
Which create table statement is valid?
A. Option A
B. Option B
C. Option C
D. Option D
Correct Answer: D
Explanation/Reference:
Explanation:
PRIMARY KEY Constraint
A PRIMARY KEY constraint creates a primary key for the table. Only one primary key can be created for each table. The PRIMARY KEY constraint is a column or a set of columns that uniquely identifies each row in a table. This constraint enforces the uniqueness of the column or column combination and ensures that no column that is part of the primary key can contain a null value.
Note: Because uniqueness is part of the primary key constraint definition, the Oracle server enforces the uniqueness by implicitly creating a unique index on the primary key column or columns.
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