search
Login

Categories


C Books Guide and List
C++ Books Guide and List
Best Java Books

3.8k questions

4k answers

117 comments

10.7k users

0 votes
19 views
asked Geek 15.3k points 16 41 63

1 Answer

0 votes
 
Cross Join A cross join that does not have a WHERE clause produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table. The common example is when company wants to combine each product with a pricing table to analyze each product at each price.
Inner Join A join that displays only the rows that have a match in both joined tables is known as inner Join. This is the default type of join in the Query and View Designer.
Outer Join A join that includes rows even if they do not have related rows in the joined table is an Outer Join. You can create three different outer join to specify the unmatched rows to be included:
Left Outer Join: In Left Outer Join all rows in the first-named table i.e. "left" table, which appears leftmost in the JOIN clause are included. Unmatched rows in the right table do not appear.
Right Outer Join: In Right Outer Join all rows in the second-named table i.e. "right" table, which appears rightmost in the JOIN clause are included. Unmatched rows in the left table are not included.
Full Outer Join: In Full Outer Join all rows in all joined tables are included, whether they are matched or not.
Self Join This is a particular case when one table joins to itself, with one or two aliases to avoid confusion. A self join can be of any type, as long as the joined tables are the same. A self join is rather unique in that it involves a relationship with only one table. The common example is when company has a hierarchal reporting structure whereby one member of staff reports to another. Self Join can be Outer Join or Inner Join.
 
answered Advisor 6.3k points 5 21 31

Related questions

0 votes
1 answer 38 views
38 views
I heard that JOINs (SQL) are useless. Using joins is less efficient than making several requests and link tables in the code (C# or Java). Joins are for lazy people that don't care about performance. Is this true? Should we avoid using joins?
asked om Sr Member 1.3k points 7 16 31
0 votes
1 answer 16 views
16 views
asked smith Geek 15.3k points 16 41 63
0 votes
1 answer 136 views
136 views
What is a self join and give an example.
asked anonymous
0 votes
1 answer 14 views
0 votes
1 answer 137 views
137 views
asked rajesh Guru 39.1k points 10 21 33
...