注意： 首先在datagrip中使用表中欄位為中文時報錯需要修改編碼格式

語句如下:school為資料庫名

alter database mt character set utf8;
# 修改指定庫的欄位
alter table food default character set  utf8;
# 修改指定表的欄位
alter table food convert to character set utf8;
# 修改指定表中所有的欄位

常用語句：

# alter database mt character set utf8;
# # 修改指定庫的欄位
# alter table food default character set  utf8;
# # 修改指定表的欄位
# alter table food convert to character set utf8;
# # 修改指定表中所有的欄位
insert into food (food_name,address) VALUES ("蛋糕","北京");
insert into food (food_name,address) VALUES ("蛋糕1",address) VALUES ("蛋糕2",address) VALUES ("蛋糕3","北京");
# 插入一條資料在指定表中前面的為屬性名 後面為值 注意兩者順序應當一致
update food set address = "南京" where address = "北京";
# 更改指定條件的那一條資料 set是更改的新值 where是選中的條件
update food set address = "西安",food_name = "喬科爾裡" where  id = 1;
# 修改多個用逗號隔開
select id from food where address = "西安";
# 查詢指定條件的資訊
select count(1) from food;
# 函式返回指定列的總數數目（NULL 不計入）；
select count(1) from food where address = "西安";
# 查詢指定條件的資料總數
 select sum(id) from food;
# 求表中某一屬性的值的和
select sum(id)/count(1) from food;
# 求指定屬性的值的平均數
select avg(id) as taotao from food;
# as關鍵字用於將屬性名新增別名
select address,count(1),avg(id) from food group by address;
# group by 將資料依據address分類並求和 注意對那一個屬性分組就顯示那一個屬性 多餘不可以
select * from food limit 3,4;
# limit表示限制量 前面數字表示飄移量，後面表示每頁顯示多少 正序顯示
select * from food order by id desc ;
# order by 表示通過某一屬性排序 正序 倒敘是新增desc
delete from food where id = 10;
delete from food where food_name = "蛋糕";