JOINS: The joins are used to get or retrieve records from more than one tables.It combines rows from two or more tables based on a common column between them. The four types of joins are used. These are:
a) LEFT JOIN
b) INNER JOIN
c) RIGHT JOIN
d) FULL JOIN
a) LEFT JOIN: The LEFT JOIN is also known as LEFT OUTER JOIN. When we use left join then It fetches all records from the left table and the matched records from the right table. And if there is no matching row in the right side table then the result shows NULL. The syntax of Left join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
LEFT JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
The TABLE1 is a left side table and TABLE2 is a right side table.
b) INNER JOIN: The INNER JOIN is also known as EQUI JOIN. When we use inner join then it fetches all records that have matched records in two or more tables. The syntax of inner join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
JOIN or INNER JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
c) RIGHT JOIN: The RIGHT JOIN is also known as RIGHT OUTER JOIN. When we use right join then It fetches all records from the right table and the matched records from the left table. And if there is no matching row in the left side table then the result shows NULL.The right join or right outer join is similar to left join. The syntax of right join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
RIGHT JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
The TABLE1 is a left side table and TABLE2 is a right side table.
d) FULL JOIN: The FULL JOIN is also known as FULL OUTER JOIN. When we use full join then It fetches all records from the left table and right table.And if there is no matching row in the right side table then the result shows NULL The syntax of full join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
FULL JOIN or FULL OUTER JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
The TABLE1 is a left side table and TABLE2 is a right side table.
a) LEFT JOIN
b) INNER JOIN
c) RIGHT JOIN
d) FULL JOIN
a) LEFT JOIN: The LEFT JOIN is also known as LEFT OUTER JOIN. When we use left join then It fetches all records from the left table and the matched records from the right table. And if there is no matching row in the right side table then the result shows NULL. The syntax of Left join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
LEFT JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
The TABLE1 is a left side table and TABLE2 is a right side table.
b) INNER JOIN: The INNER JOIN is also known as EQUI JOIN. When we use inner join then it fetches all records that have matched records in two or more tables. The syntax of inner join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
JOIN or INNER JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
c) RIGHT JOIN: The RIGHT JOIN is also known as RIGHT OUTER JOIN. When we use right join then It fetches all records from the right table and the matched records from the left table. And if there is no matching row in the left side table then the result shows NULL.The right join or right outer join is similar to left join. The syntax of right join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
RIGHT JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
The TABLE1 is a left side table and TABLE2 is a right side table.
d) FULL JOIN: The FULL JOIN is also known as FULL OUTER JOIN. When we use full join then It fetches all records from the left table and right table.And if there is no matching row in the right side table then the result shows NULL The syntax of full join is as:
SELECT
COLUMN1(ID), COLUMN2
FROM
TABLE 1
FULL JOIN or FULL OUTER JOIN
TABLE2
ON
TABLE1.COLUMN1(ID) = TABLE2.COLUMN1(ID)
The TABLE1 is a left side table and TABLE2 is a right side table.
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