mysql 大小写函数

-- 将字符串转换为小写
SELECT LOWER('Hello World') AS lower_case;

-- 将字符串转换为大写
SELECT UPPER('Hello World') AS upper_case;

-- 连接字符串并转换为大写
SELECT CONCAT('Hello', ' ', 'World') AS concatenated;
SELECT UPPER(CONCAT('Hello', ' ', 'World')) AS upper_concatenated;

-- 提取字符串的一部分并转换为大写
SELECT UPPER(SUBSTRING('Hello World', 1, 5)) AS upper_substring;

-- 去除字符串两端的空格并转换为大写
SELECT UPPER(TRIM('   Hello World   ')) AS upper_trimmed;

-- 查看数据库字符集和排序规则
SHOW CREATE DATABASE your_database_name;

-- 查看表字符集和排序规则
SHOW CREATE TABLE your_table_name;

-- 修改数据库字符集和排序规则
ALTER DATABASE your_database_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

-- 修改表字符集和排序规则
ALTER TABLE your_table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

-- 创建索引
CREATE INDEX idx_lower_name ON your_table_name (LOWER(name));