Daum Most Frequently Asked Latest Oracle Interview Questions Answers
What is the fastest query method to fetch data from the table?
Row can be fetched from table by using ROWID. Using ROW ID is the fastest query method to fetch data from the table.
What is the maximum number of triggers that can be applied to a single table?
12 is the maximum number of triggers that can be applied to a single table.
How to display employee records who gets more salary than the average salary in the department?
This can be done by this query –
Select * from employee where salary>(select avg(salary) from dept, employee where dept.deptno = employee.deptno;
1
Select * from employee where salary>(select avg(salary) from dept, employee where dept.deptno = employee.deptno;
What do you mean by GROUP BY Clause?
A GROUP BY clause can be used in select statement where it will collect data across multiple records and group the results by one or more columns.
What is a sub query and what are the different types of subqueries?
Sub Query is also called as Nested Query or Inner Query which is used to get data from multiple tables. A sub query is added in the where clause of the main query.
There are two different types of subqueries:
Correlated sub query
A Correlated sub query cannot be as independent query but can reference column in a table listed in the from list of the outer query.
Non-Correlated subquery
This can be evaluated as if it were an independent query. Results of the sub query are submitted to the main query or parent query.
What is cross join?
Cross join is defined as the Cartesian product of records from the tables present in the join. Cross join will produce result which combines each row from the first table with the each row from the second table.
What are temporal data types in Oracle?
Oracle provides following temporal data types:
Date Data Type – Different formats of Dates
TimeStamp Data Type – Different formats of Time Stamp
Interval Data Type – Interval between dates and time
How do we create privileges in Oracle?
A privilege is nothing but right to execute an SQL query or to access another user object. Privilege can be given as system privilege or user privilege.
[sql]GRANT user1 TO user2 WITH MANAGER OPTION;[/sql]
What is the difference between TRANSLATE and REPLACE?
Translate is used for character by character substitution and Replace is used substitute a single character with a word.
How do we display rows from the table without duplicates?
Duplicate rows can be removed by using the keyword DISTINCT in the select statement.
What is the usage of Merge Statement?
Merge statement is used to select rows from one or more data source for updating and insertion into a table or a view. It is used to combine multiple operations.
What is NULL value in oracle?
NULL value represents missing or unknown data. This is used as a place holder or represented it in as default entry to indicate that there is no actual data present.
What is USING Clause and give example?
The USING clause is used to specify with the column to test for equality when two tables are joined.
[sql]Select * from employee join salary using employee ID[/sql]
Employee tables join with the Salary tables with the Employee ID.
What is VArray?
VArray is an oracle data type used to have columns containing multivalued attributes and it can hold bounded array of values.
How do we get field details of a table?
Describe <Table_Name> is used to get the field details of a specified table.
What is the difference between rename and alias?
Rename is a permanent name given to a table or a column whereas Alias is a temporary name given to a table or column. Rename is nothing but replacement of name and Alias is an alternate name of the table or column.
What is a View?
View is a logical table which based on one or more tables or views. The tables upon which the view is based are called Base Tables and it doesn’t contain data.
What is a cursor variable?
A cursor variable is associated with different statements which can hold different values at run time. A cursor variable is a kind of reference type.
What is the fastest query method to fetch data from the table?
Row can be fetched from table by using ROWID. Using ROW ID is the fastest query method to fetch data from the table.
What is the maximum number of triggers that can be applied to a single table?
12 is the maximum number of triggers that can be applied to a single table.
How to display employee records who gets more salary than the average salary in the department?
This can be done by this query –
Select * from employee where salary>(select avg(salary) from dept, employee where dept.deptno = employee.deptno;
1
Select * from employee where salary>(select avg(salary) from dept, employee where dept.deptno = employee.deptno;
A GROUP BY clause can be used in select statement where it will collect data across multiple records and group the results by one or more columns.
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| Daum Most Frequently Asked Latest Oracle Interview Questions Answers |
What is a sub query and what are the different types of subqueries?
Sub Query is also called as Nested Query or Inner Query which is used to get data from multiple tables. A sub query is added in the where clause of the main query.
There are two different types of subqueries:
Correlated sub query
A Correlated sub query cannot be as independent query but can reference column in a table listed in the from list of the outer query.
Non-Correlated subquery
This can be evaluated as if it were an independent query. Results of the sub query are submitted to the main query or parent query.
What is cross join?
Cross join is defined as the Cartesian product of records from the tables present in the join. Cross join will produce result which combines each row from the first table with the each row from the second table.
What are temporal data types in Oracle?
Oracle provides following temporal data types:
Date Data Type – Different formats of Dates
TimeStamp Data Type – Different formats of Time Stamp
Interval Data Type – Interval between dates and time
How do we create privileges in Oracle?
A privilege is nothing but right to execute an SQL query or to access another user object. Privilege can be given as system privilege or user privilege.
[sql]GRANT user1 TO user2 WITH MANAGER OPTION;[/sql]
What is the difference between TRANSLATE and REPLACE?
Translate is used for character by character substitution and Replace is used substitute a single character with a word.
How do we display rows from the table without duplicates?
Duplicate rows can be removed by using the keyword DISTINCT in the select statement.
What is the usage of Merge Statement?
Merge statement is used to select rows from one or more data source for updating and insertion into a table or a view. It is used to combine multiple operations.
What is NULL value in oracle?
NULL value represents missing or unknown data. This is used as a place holder or represented it in as default entry to indicate that there is no actual data present.
What is USING Clause and give example?
The USING clause is used to specify with the column to test for equality when two tables are joined.
[sql]Select * from employee join salary using employee ID[/sql]
Employee tables join with the Salary tables with the Employee ID.
What is VArray?
VArray is an oracle data type used to have columns containing multivalued attributes and it can hold bounded array of values.
How do we get field details of a table?
Describe <Table_Name> is used to get the field details of a specified table.
What is the difference between rename and alias?
Rename is a permanent name given to a table or a column whereas Alias is a temporary name given to a table or column. Rename is nothing but replacement of name and Alias is an alternate name of the table or column.
What is a View?
View is a logical table which based on one or more tables or views. The tables upon which the view is based are called Base Tables and it doesn’t contain data.
What is a cursor variable?
A cursor variable is associated with different statements which can hold different values at run time. A cursor variable is a kind of reference type.
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