A JOIN clause is used to combine two or more related tables. Tables are related to each other using foreign key constraints
There are five types of joins in SQL Server as given below
INNER JOIN – SQL Inner Join returns the rows from the tables that have matching value in columns.(inner join)
SYNTAX
SELECT COLUMN(S),... FROM TABLE T1 INNER JOIN TABLE T2ย ON T1.COLUMN = T2. COLUMNย WHERE CONDITIONS..
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LEFT OUTER JOIN –ย SQL LEFT JOIN or LEFT OUTER JOIN returns all rows from the left table and the matching rows fromย theย right table. If a row in the left table does not have any matching row in the right table then columns of the right table will have nulls value.(Left Outer Join)
SYNTAX
SELECT COLUMN(S),... FROM TABLE T1 LEFT OUTER JOIN TABLE T2ย ON T1.COLUMN = T2. COLUMNย WHERE CONDITIONS..
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RIGHT OUTER JOIN – SQL RIGHT JOIN or RIGHT OUTER JOIN returns all rows from the right table and the matching rowsย from the left table.ย If a row in the right table does not have any matching row in the left table then columns of the left table will have nulls value.(Right Outer Join)
SYNTAX
SELECT COLUMN(S),... FROM TABLE T1 RIGHT OUTER JOIN TABLE T2ย ON T1.COLUMN = T2. COLUMNย WHERE CONDITIONS..
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FULL OUTER JOINย – SQL FULL JOIN orย FULL OUTER JOIN returns rows from both left and right tables, with the matching rows from both tables where available. If there is no match, then missing side will have null values.(Full Outer Join)
SYNTAX
SELECT COLUMN(S),... FROM TABLE T1 FULL OUTER JOIN TABLE T2ย ON T1.COLUMN = T2. COLUMNย WHERE CONDITIONS..
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CROSS JOIN –ย SQL CROSS JOIN returns a result set which is the number of rows in the first table multiplied by the number of rows in the second table if no WHERE clause is used along with CROSS JOIN or we can say it returns the Cartesian product of rows from the row sets in the join. (Cross Join)
SYNTAX
SELECT * FROM TABLE T1 CROSS JOIN TABLE T2
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