what is difference between primary key and unique key
?
Answer Posted / chandonline
Basic difference between primary key and unique is that primary key is used to define a table in other tables for preventing data from anomalies,and unique key is used in a table to apply unifications among different values or columns of a tables and only in that table obviously.Their is no usage of unique key outward a table but primary key is often used to make relations between other tables.
| Is This Answer Correct ? | 3 Yes | 0 No |
Post New Answer View All Answers
What is the maximum length of an extended property?
fact table and dimension table containg one to many relationship or many to one relastionship
A) Which two are benefits of Teradata's support for ANSI Standard SQL? (Choose two.) 1.data is distributed automatically 2.queries get optimized to better plans 3.submit queries from other database systems 4.can interface with BI tools B) Which statement is true when comparing the advantages of third normal form to star schema? 1.Star schema tends to have fewer entities. 2.Star schema requires additional data storage. 3.Third normal form tends to have fewer entities. 4.Third normal form requires additional data storage. C)Which two sets of functions does the Parsing Engine (PE) perform? (Select two.) 1.sorting, formatting, and aggregating of the final answer set 2.flow control of the data to and from the participating tables 3.SQL statement interpretation, syntax validation, and semantic evaluation 4.dispatching the step execution sequence to the AMP via the BYNET D) Which two can be achieved with Teradata Active System Management (TASM)? (Choose two.) 1.disable hardware 2.react to hardware failure 3.influence response times 4.collect metadata E) Which three mechanisms can be used to ensure security within the Teradata Database? (Choose three.) 1.views 2.spool limits 3.roles 4.access rights 5.profiles
What are the key features of dbms?
How can you log an error to the server event log from a stored procedure?
How to customize error conditions.
Explain about relational database management systems?
You are testing the performance of a query the first time you run the query, the performance is slow. the second time you run the query, the performance is fast. why is this?
What are the types of database model?
What is dbms and its application?
Explain what a database is?
How to replace not in with not exist?
State the acid rules?
Explain the role of indexing in databases?
Can an extended stored procedure be called from inside a user-defined function?