在MySQL中,OR條件查詢通常會導致性能問題,特別是在大型數據集上。為了提高查詢性能,可以考慮以下改寫策略:
SELECT * FROM table_name WHERE condition1
UNION ALL
SELECT * FROM table_name WHERE condition2
SELECT * FROM table_name WHERE column_name IN (value1, value2, value3)
SELECT * FROM table_name WHERE EXISTS (
SELECT 1 FROM another_table WHERE condition1
) OR EXISTS (
SELECT 1 FROM another_table WHERE condition2
)
SELECT * FROM table_name
WHERE CASE
WHEN condition1 THEN 1
WHEN condition2 THEN 1
ELSE 0
END = 1
通過以上改寫策略,可以有效提高OR條件查詢的性能,使查詢更加高效。