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- Question
Foreign key in DBMS is
- Correct Answer
- Foreign keys are the columns of a table that points to the primary key of another table They act as a cross-reference between tables In detail : A Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table In simpler words, the foreign key is defined in a second table, but it refers to the primary key or a unique key in the first table
- 1. A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls
Options- A. TRUE
- B. FALSE Discuss
- 2. Which command is used to return maximum value from result set?
Options- A. MAX
- B. MIN
- C. MAXIMUM
- D. MAXI Discuss
- 3. What is the difference between a Local and a Global temporary table? Discuss
- 4. What is Log Shipping? Discuss
- 5. Explain Data Definition Language Discuss
- 6. Difference between Union and Union all? Discuss
- 7. Candidate Key in DBMS? Discuss
- 8. The SQL keyword(s) ________ is used with wildcards.
Options- A. LIKE only
- B. IN only
- C. NOT IN only
- D. IN and NOT IN Discuss
- 9. Which of the following is a comparison operator in SQL?
Options- A. LIKE
- B. BETWEEN
- C. =
- D. All of the above Discuss
- 10. Go command is a signal to execute the entire batch of SQL statements after previous Go
Options- A. TRUE
- B. FALSE Discuss
Oracle Certification problems
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Correct Answer: TRUE
Explanation:
Because a table can have only one primary key
Correct Answer: MAX
Explanation:
MAX command is used to return maximum value from result setMAX
Correct Answer: Local : Only available to the current Db connection for current user and are cleared when connection is closed Multiple users can?t share a local temporary table Global: Available to any connection once created They are cleared when the last connection is closed Can be shared by multiple user sessions
Correct Answer: Log shipping defines the process for automatically taking backup of the database and transaction files on a SQL Server and then restoring them on a standby/backup server This keeps the two SQL Server instances in sync with each other In case production server fails, users simply need to be pointed to the standby/backup server Log shipping primarily consists of 3 operations: Backup transaction logs of the Production server Copy these logs on the standby/backup server Restore the log on standby/backup server
Correct Answer: Data Definition Language (DDL):- are the SQL statements that define the database structure Example: CREATE ALTER DROP TRUNCATE COMMENT RENAME
Correct Answer: The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table A UNION statement effectively does a SELECT DISTINCT on the results set
Correct Answer: A candidate key is a column, or set of columns, in a table that can uniquely identify any database record without referring to any other data Each table may have one or more candidate keys, but one candidate key is unique, and it is called the primary key
Correct Answer: LIKE only
Correct Answer: All of the above
Explanation:
LIKE, BETWEEN and = operators are used for comparison in SQL. Comparison operators test whether two expressions are the same. Comparison operators can be used on all expressions except expressions of the text, ntext, or image data types.
Correct Answer: TRUE
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