Shulou(Shulou.com)06/01 Report--

Examine the following statement that is used to modify the primary key constraint on the SALES table:

SQL > ALTER TABLE SALES MODIFY CONSTRAINT compete for DISABLE VALIDATE

Which three statements are true regarding the above command? (Choose three.)

A. The constraint remains valid.

B. The index on the constraint is dropped.

C. It allows the loading of data into the table using SQL * Loader.

D. New data conforms to the constraint, but existing data is not checked.

E. It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.

Check the following statement to modify the primary key constraint of the SALES table:

SQL > ALTER TABLE SALES MODIFY CONSTRAINT compete for DISABLE VALIDATE

Which three sentences are correct about the above command? (select three)

A. the constraint is still valid

B. the index on the constraint is deleted

C. allow data to be loaded into tables using SQL*Load

D. the new data meets the constraints, and the existing data will not be checked

E. allow INSERT/UPDATE/DELETE SQL statements on the table for data

An is correct because DISABLE VALIDATE still has constraints on existing data

B correct, because the DISABLE VALIDATE status deletes the index

C is correct because DISABLE VALIDATE has no constraints on the newly added data

D error, because DISABLE VALIDATE has constraints on existing data, and none of the new ones

E error because DISABLE VALIDATE does not allow any modifications to constrained columns

Knowledge points:

Enable constraints:

Enable (validate): enable constraints, create indexes, and enforce constraints on existing and newly added data.

Enable novalidate: enable constraints, create indexes, and enforce constraints only on newly added data, regardless of existing data in the table. Do not check existing data

Disable constraints:

Disable (novalidate): close the constraint, delete the index, and modify the data of the constraint column.

Disable validate: close constraints, delete indexes, and cannot insert / update / delete tables. Do not check the new data

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