Difference between JOIN and UNION in SQL
JOIN:
JOIN in SQL is used to combine data from many tables based on a matched condition between them. The data combined using JOIN statement results into new columns.
Consider the two tables:
Boys
Girls
Example:
sql> SELECT Boys.Name, Boys.Age, Girls.Address, FROM Boys INNER JOIN Girls ON Boys.Rollno = Girls.Rollno;
The resultant table is:
UNION:
UNION in SQL is used to combine the result-set of two or more SELECT statements. The data combined using UNION statement is into results into new distinct rows.
Example:
sql> SELECT Name FROM Boys WHERE Rollno < 16 UNION SELECT Name FROM Girls WHERE Rollno > 9
The resultant table is:
Difference between JOIN and UNION in SQL :
| JOIN | UNION |
|---|---|
| JOIN combines data from many tables based on a matched condition between them. | SQL combines the result-set of two or more SELECT statements. |
| It combines data into new columns. | It combines data into new rows |
| Number of columns selected from each table may not be same. | Number of columns selected from each table should be same. |
| Datatypes of corresponding columns selected from each table can be different. | Datatypes of corresponding columns selected from each table should be same. |
| It may not return distinct columns. | It returns distinct rows. |
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Improved By : dhruv5819
