Join Strategies

A Join statement is used to combine data or rows from two or more tables based on a common field between them. 

Different types of Joins are:

• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• FULL JOIN

INNER JOIN:

The INNER JOIN keyword selects all rows from both the tables as long as the condition satisfies. This keyword will create the result-set by combining all rows from both the tables where the condition satisfies i.e value of the common field will be the same. 

The simplest form is the inner join form.

LEFT JOIN:

This join returns all the rows of the table on the left side of the join and matching rows for the table on the right side of the join. The rows for which there is no matching row on the right side, the result-set will contain null. LEFT JOIN is also known as LEFT OUTER JOIN.

RIGHT JOIN: 

RIGHT JOIN is similar to LEFT JOIN. This join returns all the rows of the table on the right side of the join and matching rows for the table on the left side of the join. The rows for which there is no matching row on the left side, the result-set will contain null. RIGHT JOIN is also known as the RIGHT OUTER JOIN.

FULL JOIN: 

FULL JOIN creates the result-set by combining the result of both LEFT JOIN and RIGHT JOIN. The result-set will contain all the rows from both the tables. The rows for which there is no matching, the result-set will contain NULL values.