JOIN SQL

Joins are used to select matching values from two tables.

Syntax:

        
            SELECT a.columnX, b.columnY
            FROM TableA a
            JOIN TableB b
            ON a.columnZ = b.columnT
        
    

• columnX and columnZ are any columns from TableA.
• columnY and columnT are any columns from TableB.
• If the ON clause compares columns of different data types, an implicit conversion will occur, or an error will be thrown if strict mode is enabled in some database management systems.
• Example: ON a.Age = b.FullName (Both Age and FullName are converted to strings for comparison).

There are four types of joins:

• Inner Join
• Left Join
• Right Join
• Full Join

Note: A self join is a type of join where a table is joined with itself using the same syntax as for other joins (e.g., Inner Join, Left Join, Right Join, Full Join).