Home » Oracle » 1z0-051 » Evaluate the following SQL commands:
Evaluate the following SQL commands:
The command to create a table fails. Identify the reason for the SQL statement failure?
(Choose all that apply.)
A. You cannot use SYSDATE in the condition of a CHECK constraint.
B. You cannot use the BETWEEN clause in the condition of a CHECK constraint.
C. You cannot use the NEXTVAL sequence value as a DEFAULT value for a column.
D. You cannot use ORD_NO and ITEM_NO columns as a composite primary key because ORD NO is also the FOREIGN KEY.
Correct Answer: AC
Explanation/Reference:
Explanation:
CHECK Constraint
The CHECK constraint defines a condition that each row must satisfy. The condition can use the same constructs as the query conditions, with the following exceptions:
References to the CURRVAL, NEXTVAL, LEVEL, and ROWNUM pseudocolumns
Calls to SYSDATE, UID, USER, and USERENV functions
Queries that refer to other values in other rows
A single column can have multiple CHECK constraints that refer to the column in its definition.
There is no limit to the number of CHECK constraints that you can define on a column.
CHECK constraints can be defined at the column level or table level.
CREATE TABLE employees
(…
salary NUMBER(8,2) CONSTRAINT emp_salary_min
CHECK (salary > 0),
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