Answers for "why we use joins in sql"

SQL
20

joins in sql

INNER JOIN:
is used when retrieving data from multiple
tables and will return only matching data.

LEFT OUTER JOIN:
is used when retrieving data from
multiple tables and will return
left table and any matching right table records.

RIGHT OUTER JOIN:
is used when retrieving data from
multiple tables and will return right
table and any matching left table records

FULL OUTER JOIN:
is used when retrieving data from
multiple tables and will return both
table records, matching and non-matching.



INNER JOIN :
SELECT select_list From TableA A
Inner Join TableB B
On A.Key = B.Key


LEFT OUTER JOIN :
SELECT select_list From TableA A
Left Join TableB B
On A.Key = B.Key

(where b.key is null)//For delete matching data



RIGTH OUTER JOIN :
SELECT select_list From TableA A
Right Join TableB B
On A.Key = B.Key


FULL JOIN :
SELECT select_list From TableA A
FULL OUTER Join TableB B
On A.Key = B.Key
Posted by: Guest on December-05-2020
2

joins in sql server

/*General Formula For Joins*/
SELECT Column_List
FROM Left_Table_Name
JOIN_TYPES Right_Table_Name
ON Join_Condition

/*INNER JOIN - Matching Rows + Non Matching Rows are Eliminated
  LEFT JOIN - Matching Rows + Non Matching Rows from the Left table
  RIGHT JOIN - Matching Rows + Non Matching Rows from the Right table
  FULL JOIN - Matching Rows + Non Matching Rows from the Both  tables
  CROSS JOIN - Return cartesian product of the tables involved in the Join
  SELF JOIN - Return each table row is combined with itself and with every other table row.
  The SELF JOIN can be thought of as a JOIN of two copies of the same tables.*/
  
/*Cross Join*/
SELECT Column_List
FROM Left_Table_Name
CROSS JOIN Right_Table_Name
Posted by: Guest on June-15-2021

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