Interested to Buy Any Domain ? << Click Here >> for more details...
what are the advantages of primary key over unique+notnull
- 7 Answers
- 22300 Views
- Consultancy, LGS, Oracle, I also Faced
- E-Mail Answers
Answer Posted / kamal
we are able to create a primary key for combination of more
than 1 column. which is not possible in Unique,we should
create unique key for each and every column in the table
individually.
ex . we can create a primary key for (Name,DOB,address)- ie
combination of these three columns be unique.
| Is This Answer Correct ? | 3 Yes | 5 No |
Post New Answer View All Answers
How do I count records in sql?
What is clause?
How to pronounce postgresql?
Is subquery faster than join?
Explain isolation levels. : Transact sql
Does postgresql run on the cloud?
Table1: Col1 col2 1 2 10 3 4 89 5 6 Table:2 Col1 col2 3 2 9 5 4 7 6 87 With the help of table1 and table2 write a query to simulate the fallowing results. Output1: Col1 col2 1 2 2 3 3 4 4 5 5 6 Output2: Col1 col2 2 3 10 4 5 89 6 7 1.Write query for single row to multiple row using sql statements. Eg:a,b,c,d,e,f Change to A B C D E F 2. Write query for multiple row to single row using sql statements. Eg2 A B C D E F Change to Eg:a,b,c,d,e,f Table1: Col1 col2 8 5 2 9 4 2 5 1.Write a query to select all the rows from a table1,if the value of A is null then corresponding B’s value should be printed in A’s value.if the value of A is null in that table then corresponding B’s value should be printed as 30. 2. write a query to find the sum of A and B .display the max among both. 3.write a query to find total number of rows from table 1. Note: if any column value is null in a row then that row should be considered as 2 rows. 4.write a query to display all the records of table1 except A containg 2 as well B containg 5. 5.rewrite the fallowing without using join and group by. Select b.title,max(bc.returneddate –bc.checkoutdate)” mostdaysout” From bookshelf_checkout bc, Book shelf B Where bc.title(+)=b.title Group by b.title. 6.rewrite fallowing query Select id_category from category_master X where exists (select 1 from sub_category Y where X.id_category=Y.id_category) Customer: Name phone1 phone2 phone3 bitwise A 23456 67890 12345 --- B 67459 89760 37689 --- Don’t_call Col1 67890 37689 1.q) update the customer table of bitwise with 1 or 0. Exists in don’t_call table menas show -1 Other wise -0. Output. Name bitwise A 010 B 010
How to change the order of columns in Oracle SQL Plus ?
Is big data nosql?
What is sql in oracle?
What is record in pl sql?
how is myisam table stored? : Sql dba
What is trigger in sql? Explain
What is multiple partition?
How to run sql*plus commands in sql developer?
