[Mysql] LOWER函数 | UPPER函数

LOWER函数

形式: LOWER(str)

str:要转换的字符串

将字符串str的所有字母转换成小写字母

-- 将字符串HELLO WORLD!转换为小写
SELECT LOWER('HELLO WORLD!'); -- hello world!

UPPER函数

形式: UPPER(str)

str:要转换的字符串

将字符串str的所有字母转换成大写字母

-- 将字符串hello world!转换为大写
SELECT UPPER('hello world!'); -- HELLO WORLD!

练习案例

导入数据

DROP TABLE IF EXISTS `vendors`;
CREATE TABLE `vendors`  (
  `id` int(11) NOT NULL,
  `vend_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

INSERT INTO `vendors` VALUES (1, 'Acme');
INSERT INTO `vendors` VALUES (2, 'Anvils R Us');
INSERT INTO `vendors` VALUES (3, 'Furball Inc.');
INSERT INTO `vendors` VALUES (4, 'Jet Set');
INSERT INTO `vendors` VALUES (5, 'Jouets Ft Ours');
INSERT INTO `vendors` VALUES (6, 'LT Supplies');

vendors表

使用SQL语句，生成如下结果:

SELECT vend_name, 
       UPPER(vend_name)AS vend_name_upper,
       LOWER(vend_name)AS vend_name_lower
FROM vendors
ORDER BY vend_name;