SELECT prod_name from Products;
SELECT distinct vend_id From products; --使用DISTINCT 去除重复
SELECT prod_name
FROM products
LIMIT 5 OFFSET 5; --行内注释 ORACLE 可以使用where ROWNUM <= 5, MYSQL SQLITE 使用 LIMIT限制取得的行数
SELECT prod_name
FROM products
ORDER BY prod_name; --指定ORDER BY 子句时，需要保证它是SELECT语句中最后一条子句
SELECT prod_id,prod_price,prod_name
FROM products
ORDER BY prod_price,prod_name; --多列排序
SELECT prod_id,prod_price,prod_name
FROM products
ORDER BY 2 DESC,3; -- 按列位置进行排序，DESC 降序 ASC 升序（默认）
/*过滤数据 where
*/
SELECT prod_name,prod_price
FROM products
WHERE prod_price = 3.49; --过滤价格等于3.49的供应商列
SELECT vend_id,prod_name
FROM products
WHERE vend_id != 'DLL01';
SELECT prod_name,prod_price
FROM products
WHERE prod_price BETWEEN 5.99 AND 9.49; --between and 是包含关系
SELECT cust_name,cust_email
FROM customers
WHERE cust_email IS NULL; --判断是否空值 IS NULL