Multiple choice technology databases

Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Which three statements insert a row in to the table? (Choose three). A - INSERT INTO employees VALUES (NULL, 'John', 'Smith'); B - INSERT INTO employees(first_name, last_name) VALUES ('John', 'Smith'); C - INSERT INTO employees VALUES ('1000', 'John', NULL); D - INSERT INTO employees(first_name, last_name, employee_id) VALUES ('1000', 'John', 'Smith'); E - INSERT INTO employees(employee_id) VALUES (1000); F - INSERT INTO employees(employee_id,first_name,last_name) VALUES (1000,'John',' ');

  1. A, B, D

  2. C, D, E

  3. C, E, F

  4. B, D, F
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option C inserts NULL for employee_id (allowed since it's only PK if defined as NOT NULL), E inserts only employee_id (other columns default to NULL), and F inserts employee_id, first_name='John', and a space for last_name. Options A (NULL for PK with NOT NULL), B (missing employee_id), and D (wrong column order) fail.

AI explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) INSERT INTO employees VALUES (NULL, 'John', 'Smith'); This option is incorrect because it tries to insert a NULL value for the primary key column EMPLOYEE_ID, which is not allowed.

Option B) INSERT INTO employees(first_name, last_name) VALUES ('John', 'Smith'); This option is incorrect because it does not provide a value for the primary key column EMPLOYEE_ID, which is required.

Option C) INSERT INTO employees VALUES ('1000', 'John', NULL); This option is correct because it provides values for all three columns (EMPLOYEE_ID, FIRST_NAME, LAST_NAME) and does not violate any constraints.

Option D) INSERT INTO employees(first_name, last_name, employee_id) VALUES ('1000', 'John', 'Smith'); This option is incorrect because it provides a value 'Smith' for the column EMPLOYEE_ID, which is defined as a NUMBER data type.

Option E) INSERT INTO employees(employee_id) VALUES (1000); This option is correct because it provides a value for the primary key column EMPLOYEE_ID, which is required. It does not provide values for the other columns, but that is allowed as long as they have default values or accept NULL values.

Option F) INSERT INTO employees(employee_id,first_name,last_name) VALUES (1000,'John',' '); This option is correct because it provides values for all three columns (EMPLOYEE_ID, FIRST_NAME, LAST_NAME) and does not violate any constraints.

The correct answer is C. The three statements that insert a row into the table are C, E, and F. These statements provide valid values for all columns and do not violate any constraints.

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