Which product is returned in a join query have no join condition:
A Cartesian coordinate system is a coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates.
A CROSS JOIN or CARTESIAN JOIN returns the Cartesian product of an available set of records from multiple joined tables. Thus, this join would equate to an inner join in which the join-condition always evaluates to either True or wherever the join-condition is not present in the statement.
In SQL the statement select * from R, S is equivalent to
A Cartesian coordinate system is a coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates.
A CROSS JOIN or CARTESIAN JOIN returns the Cartesian product of an available set of records from multiple joined tables. Thus, this join would equate to an inner join in which the join-condition always evaluates to either True or wherever the join-condition is not present in the statement.
Which join refers to join records from the write table that have no matching key in the left table are include in the result set:
A right outer join will return all the rows that an inner join returns plus one row for each of the other rows in the second table that did not have a match in the first table. It is the same as a left outer join with the tables specified in the opposite order.
Outer joins are of following three types.
Right Outer Join : The right join operation returns all record from right table and matching records from the left table. On a matching element not found in left table, NULL is represented in that case.
Which product is returned in a join query have no join condition:
A Cartesian coordinate system is a coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates.
A CROSS JOIN or CARTESIAN JOIN returns the Cartesian product of an available set of records from multiple joined tables. Thus, this join would equate to an inner join in which the join-condition always evaluates to either True or wherever the join-condition is not present in the statement.
In RDBMS, which type of Join returns all rows that satisfy the join condition ?
Concept:
Join operation is used to combine related tuples from two relations into single tuples. Join operation can be stated in terms of Cartesian product followed by SELECT operation.
Join condition form:
Explanation:
There are various variations of join operations such as equi-join, natural join, theta join, inner join, outer join.
Given two tables R1(x, y) and R2(y, z) with 50 and 30 number of tuples respectively. Find maximum number of tuples in the output of natural join between tables R1 and R2 i.e. R1 * R2? (*. Natural Join)
Concept:
A natural join is based on common attributes or common columns to join two tables or relations.
Explanation:
Consider an example, suppose there are two tables Employee(Eid, Ename) consists of 5 tuples and department(Eid, Did) consists of 3 tuples only.
Eid |
Ename |
1 |
E1 |
1 |
E2 |
1 |
E3 |
1 |
E4 |
1 |
E5 |
Eid |
Did |
1 |
D1 |
1 |
D2 |
1 |
D3 |
Natural join of employee and department(Employee * Department) gives:
5 × 3 = 15
So, maximum number of tuples in natural join are from the relation having minimum tuples. So, in given question, R2 contains 30 tuples, so , maximum number of tuples in the output of natural join between tables R1 and R2 i.e. R1 * R2 = 50 × 30 = 1500.
Total MCQS : 20
gradeTotal MCQS : 30
gradeTotal MCQS : 230
gradeTotal MCQS : 15
gradeTotal MCQS : 31
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