MySQL Join Improvement

mysql-join-query-tips.sql

# QUERY WITH CONDITION IN WHERE CLUASE FOR JOINED TABLE
SELECT TAB_A.COL1, TAB_B.COL1 FROM TAB_A 
	LEFT OUTER JOIN TAB_B ON TAB_A.COL3 = TAB_B.COL3 
WHERE TAB_A.COL1=123 AND TAB_B.COL2=456;

# OPTIMIZED VERSION - MOVE JOINED TABLE CONDITION ALONG WITH JOIN CONDITION TO REDUCE ROW FILTERATION
SELECT TAB_A.COL1, TAB_B.COL1 FROM TAB_A 
	LEFT OUTER JOIN TAB_B ON TAB_A.COL3 = TAB_B.COL3 
		AND TAB_B.COL2=456 
WHERE TAB_A.COL1=123;