DATABASE MANAGEMENT SYSTEMS CONCEPTS OBJECTIVE INTERVIEW QUESTIONS 1
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Q1 . what are RDMS systems?
SOLUTION
It is a way of storing data by finding the relation between the data that is being stored.These are data bases that store data as per EF CODD proposed method.
Q2 . what is a primary key?
SOLUTION
It is a unique field value to identify a row in a table.For example roll number of a student in school.
Q3 . what is a foreign key?
SOLUTION
It is a field to reference the data uniquely from this table to data in another table using a field in the other table.The field in that table can be its primary key.
Q4 . What is a left join operation?
SOLUTION
it fetches the records from the primary or left side table and also the ones that match it in the right side table.If nothing matches in the right side table then no records are returned from the right side table.
Q5 . what is an inner join operation?
SOLUTION
The inner join only fetches the common records in both the tables.
Q6 . what is outer join?
SOLUTION
The outer join fetches all records from both the tables.
Q7 . what are procedures?
SOLUTION
procedure in sql are small programs that can be invoked and executed as per requirement.
Q8 . what are triggers?
SOLUTION
Triggers are small programs that are triggered as a result of occurrence of an event,For example we can create trigger for every new row executed in a table.
Q9 . what are aggregate functions?
SOLUTION
Aggregate functions are used to club multiple rows of data in order to give a disered output.Some of the aggregate functions are as follows;Count(),average(),maximum(),minimum()
Q10 . what is the purpose of group by ?
SOLUTION
As the name suggests it is used to group the output data into sets or groups of data based on a criteria(field).