Database [3i Infotech Placement]: Sample Questions 71 - 71 of 294
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Question 71
Explanation
Below the types of joins
- Inner Join
- Outer join
- Left outer join
- Right outer join
- Full join
- Inner join
The INNER JOIN keyword selects records that have matching values in both tables.
Syntax of Inner join
SELECT column_name (s)
FROM table1
INNER JOIN table2 ON table1. column_name = table2. column_name;
- Outer Join
Left Outer join:
- The left outer join keyword returns all records from the left table (table1) , and the matched records from the right table (table2) .
- The result is NULL from the right side, if there is no match.
Syntax of left outer join
SELECT column_name (s)
FROM table1
LEFT JOIN table2 ON table1. column_name = table2. column_name;
Right Outer join:
- The right outer join keyword returns all records from the right table (table2) , and the matched records from the left table (table1) .
- The result is NULL from the left side, when there is no match.
Syntax of right outer join:
SELECT column_name (s)
FROM table1
RIGHT JOIN table2 ON table1. column_name = table2. column_name;
Full Outer join:
- The FULL OUTER JOIN keyword return all records when there is a match in either left (table1) or right (table2) table records.
Full outer join syntax:
SELECT column_name (s)
FROM table1
FULL OUTER JOIN table2 ON table1. column_name = table2. column_name;
- Simple outer join is combination of left and right outerjoins.
- Apart from these there are
- Natural join: Cartisian product
- Equi join: Which includes = operator in condition
- NonEqui join: All conditional joins which do not use = in there conditions.