MySQL的謂詞是一種用于過濾和限制查詢結果的語句。謂詞允許您根據特定的條件篩選出查詢中的行，以便獲得更有用和有意義的結果。以下是一些最常用的MySQL謂詞：

-- WHERE 謂詞
SELECT * FROM orders WHERE order_date BETWEEN '2019-01-01' AND '2019-01-31';
-- AND 和 OR 謂詞
SELECT * FROM customers WHERE city = 'New York' AND state = 'NY';
SELECT * FROM customers WHERE city = 'New York' OR state = 'NY';
-- IN 和 NOT IN 謂詞
SELECT * FROM products WHERE category_id IN (1, 3, 5);
SELECT * FROM products WHERE category_id NOT IN (2, 4, 6);
-- LIKE 和 NOT LIKE 謂詞
SELECT * FROM employees WHERE last_name LIKE 'Sm%';
SELECT * FROM employees WHERE last_name NOT LIKE '%th';
-- IS NULL 和 IS NOT NULL 謂詞
SELECT * FROM customers WHERE email IS NULL;
SELECT * FROM customers WHERE email IS NOT NULL;

使用MySQL謂詞可以快速有效地查詢和篩選數據庫中的數據。這些謂詞可以組合使用，以便更細致和具體的過濾查詢結果。