过滤数据

使用WHERE语句

SELECT prod_name, prod_price
FROM Products
WHERE prod_price = 4.39;

检查单个值

SELECT prod_name, prod_price
FROM Products
WHERE prod_price < 10;

不匹配检查

SELECT prod_name,  prod_price
FROM Products
WHERE pro_proce != 'DLL01';

范围值检查

SELECT prod_name, prod_price
FROM Products
WHERE prod_proce BETWEEN 5 AND 10;

空值检查

SELECT cust_name
FROM CUSTOMERS
WHERE cust_email IS NULL;