Tag: databases

Questions Related to databases

What is true about joining tables through an equijoin
technology databases

  1. You can join a maximum of two tables through an equijoin

  2. You can join a maximum of two columns through an equijoin

  3. You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement

  4. To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.

  5. You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.

Show answer
Correct Option: E
Explanation:

To understand the concept of equijoin, the user should know the basics of SQL and joins. An equijoin is a type of join that combines columns from two or more tables based on their equality.

Let's go through each option and explain whether it is true or false:

A. You can join a maximum of two tables through an equijoin

  • This statement is false. You can join more than two tables through an equijoin.

B. You can join a maximum of two columns through an equijoin

  • This statement is false. You can join more than two columns through an equijoin.

C. You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement

  • This statement is false. You specify an equijoin condition in the WHERE clause of a SELECT statement.

D. To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.

  • This statement is false. The columns in the join condition need not be primary key and foreign key columns; they can be any columns that have the same data type and contain the same values.

E. You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.

  • This statement is true. If you want to join n tables, you need to specify a minimum of n-1 join conditions.

The Answer is: E

Which clause should you use to exclude group results?
technology databases

  1. WHERE

  2. HAVING

  3. RESTRICT

  4. GROUP BY

  5. ORDER BY

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Correct Option: B

A subquery can be used to _________.
technology databases

  1. Create groups of data

  2. Sort data in a specific order

  3. Convert data to a different format

  4. Retrieve data based on an unknown condition

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Correct Option: D

what does the sql code -922 represents?
technology databases

  1. query will retrieve only one row

  2. authorization failure

  3. no such code available

  4. rollback

Show answer
Correct Option: B
Explanation:

To answer this question, we need to know the context in which the SQL code -922 is being used. SQL codes are specific error or informational messages generated by the database management system (DBMS) when it encounters certain conditions or situations. Without context, it is difficult to determine the exact meaning of a particular SQL code.

However, in general, SQL code -922 is associated with authorization failures. This means that the user attempting to execute a particular SQL statement does not have the required permissions or privileges to perform the operation. The exact meaning and resolution of the error will depend on the specific DBMS being used and the context in which the error occurred.

Therefore, the correct answer is:

The Answer is: B. authorization failure.

choose the environments which can access DB2
technology databases

  1. TSO

  2. IMC

  3. CICS

  4. None of the above

Show answer
Correct Option: A,C

5 rows are inserted to a DB2 Table. Next 3 of those are updated, then a rollback is issued. What would happen when the rollback is issued?
technology databases

  1. returns 5 rows

  2. returns 3 rows

  3. returns all 8rows

  4. none

Show answer
Correct Option: B

Which are true regarding the use of outer joins?
technology databases

  1. You cannot use IN operator in a condition that involves an outerjoin

  2. You use (+) on both sides of the WHERE condition to perform an outerjoin

  3. You use (*) on both sides of the WHERE condition to perform an outerjoin

  4. You use an outerjoin to see only the rows that do not meet the join condition

  5. In the WHERE condition, you use (+) following the name of the column in the table

  6. You cannot link a condition that is involved in an outerjoin to another condition by

Show answer
Correct Option: D,E,F

Which two statements complete a transaction? (Choose two)
technology databases

  1. DELETE employees;

  2. DESCRIBE employees;

  3. ROLLBACK TO SAVEPOINT C;

  4. GRANT SELECT ON employees TO SCOTT;

  5. ALTER TABLE employees SET UNUSED COLUMN sal;

  6. Select MAX(sal) FROM employees WHERE department_id = 20;

Show answer
Correct Option: C,E

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

  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.

Show answer
Correct Option: C,D

Which of the following is not a valid aggregate function
technology databases

  1. COUNT

  2. SUM

  3. COMPUTE

  4. MIN

Show answer
Correct Option: C
Explanation:

To solve this question, the user needs to have knowledge about aggregate functions in SQL.

Aggregate functions are used to perform calculations on a set of values to return a single value.

Now let's go through each option and explain why it is right or wrong:

A. COUNT: This is a valid aggregate function in SQL. It returns the number of rows that match a specified condition.

B. SUM: This is a valid aggregate function in SQL. It returns the sum of a set of values.

C. COMPUTE: This is not a valid aggregate function in SQL. There is no such function as COMPUTE in SQL.

D. MIN: This is a valid aggregate function in SQL. It returns the minimum value of a set of values.

Therefore, the answer is:

The Answer is: C