Tag: databases

Quizzes (243) Questions (4862)

Questions Related to databases

Multiple choice technology databases

Evaluate the set of SQL statements: CREATE TABLE dept (deptno NUMBER(2), dname VARCNAR2(14), loc VARCNAR2(13)); ROLLBACK; DESCRIBE DEPT What is true about the set?

  1. The DESCRIBE DEPT statement displays the structure of the DEPT table.

  2. The ROLLBACK statement frees the storage space occupies by the DEPT table.

  3. The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist.

  4. The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement.
Reveal answer Fill a bubble to check yourself
A Correct answer
Full explanation
Multiple choice technology databases

The EMP table contains these columns: LAST NAME VARCHAR2(25) SALARY NUMBER(6,2) DEPARTMENT_ID NUMBER(6) You need to display the employees who have not been assigned to any department. You write the SELECT statement: SELECT LAST_NAME, SALARY, DEPARTMENT_ID FROM EMP WHERE DEPARTMENT_ID = NULL; What is true about this SQL statement?

  1. The SQL statement displays the desired results.

  2. The column in the WHERE clause should be changed to display the desired results.

  3. The operator in the WHERE clause should be changed to display the desired results.

  4. The WHERE clause should be changed to use an outer join to display the desired results.
Reveal answer Fill a bubble to check yourself
C Correct answer
Full explanation
Multiple choice technology databases

Which two are true about aggregate functions? (Choose two.)

  1. You can use aggregate functions in any clause of a SELECT statement.

  2. You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.

  3. You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.

  4. You can pass column names, expressions, constants, or functions as parameters to an aggregate function.

  5. You can use aggregate functions on a table, only by grouping the whole table as one single group.

  6. You cannot group the rows of a table by more than one column while using aggregate functions.
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Full explanation
Multiple choice technology databases

Which two statements about subqueries are true? (Choose two.)

  1. A single row subquery can retrieve data from only one table.

  2. A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.

  3. A SQL query statement can display data from table B that is referred to in its subquery, without including table B in its own FROM clause.

  4. A single row subquery can retrieve data from more than one table.

  5. A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.

  6. A multiple-row subquery cannot be used in a condition where the LIKE operator is used for comparison.
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Full explanation
Multiple choice technology databases

You added a PHONE_NUMBER column of NUMBER data type to an existing EMPLOYEES table. The EMPLOYEES table already contains records of 100 employees. Now, you want to enter the phone numbers of each of the 100 employees into the table. Some of the employees may not have a phone number available. Which data manipulation operation do you perform?

  1. MERGE

  2. INSERT

  3. UPDATE

  4. ADD

  5. ENTER

  6. You cannot enter the phone numbers for the existing employee records.
Reveal answer Fill a bubble to check yourself
C Correct answer
Full explanation