Question

Can any one suggest which one is better in this case:

1:

SELECT
    COLUMN1, 
        (SELECT 
            COLUMN2 
        FROM
            TABLE2
        WHERE 
            <some condition>) AS COLUMN2
FROM TABLE 1 

2:

SELECT
    T1.COLUMN1,
    T2.COLUMN2
FROM
    TABLE1 T1
INNER JOIN 
    TABLE2 T2 ON <some condition>

Answer 1

Just use the analysis tools to optimize your query:

http://www.databasejournal.com/features/mysql/article.php/3925251/Using-MySQLs-Analysis-Tools-to-Improve-Query-Performance.htm