mysql CookBook -读书笔记

基本语句

• 查看数据存放目录
  SHOW VARIABLES LIKE 'datadir'
• 创建新表
  CREATE TABLE new_table LIKE single_table
• 查看表结构
  SHOW CREATE TABLE new_table
• 如果数据已经存在则忽略
  insert ignore into table
• update语句中where是强制语句
  UPDATE score SET score=44 WHERE number=20180103
• replace:如果包含主键并且存在,而删除再插入,否则是新增
  REPLACE INTO single_table (id,key1,key2) VALUES(1,'a',220)
• 如果主键重复则进行更新操作
  INSERT INTO single_table (id,key1,key2) VALUES(1,'a',220) ON DUPLICATE KEY UPDATE key3='888'
• order by 第二页
  SELECT key1,key2,key3 FROM single_table ORDER BY 2 DESC
• avg
  
• 创建新用户

CREATE USER IF NOT EXISTS 'aaa'@'%'
IDENTIFIED WITH mysql_native_password
BY 'aaa'
WITH MAX_QUERIES_PER_HOUR 500
MAX_UPDATES_PER_HOUR 100;

• 另存为表
  -- 不存在表
  CREATE TABLE aaa AS SELECT * FROM single_table
  -- 存在表
  INSERT INTO aaa SELECT * FROM single_table
  -- 复制表,包含索引
  CREATE TABLE eee (LIKE single_table)
  -- 存储json字符串

SELECT emp_no,details->'$.data.title.id' FROM emp_details

INSERT INTO emp_details
VALUES(3,'{
    "status": "0000",
    "message": "success",
    "data": {
        "title": {
            "id": "001",
            "name" : "白菜"
        },
        "content": [
            {
                "id": "001",
                "value":"你好 白菜"
            },
            {
                "id": "002",
                 "value":"你好 萝卜" 
            }
        ]
    }
}');

• 美化json
  SELECT emp_no,JSON_PRETTY(details) FROM emp_details
• 看binlog
  SHOW VARIABLES LIKE 'log_bin%'
SHOW MASTER STATUS
• 清空二进制日志
  reset master
• mysqldump
  mysqldump -u root -p123456 t1 >/a.txt
  
• 开启慢查询日志
  https://blog.csdn.net/longxudong223/article/details/105053440