trigger

data/2.MySQL中阶/1.数据库组成/6. 触发器/audit.json

+{
+  "type": "code_options",
+  "author": "ccat",
+  "source": "audit.md",
+  "notebook_enable": false,
+  "exercise_id": "457f6b7e9b2b4eb58d15f12cb21a1463"
+}
\ No newline at end of file

data/2.MySQL中阶/1.数据库组成/6. 触发器/audit.md

+# 交易审计
+
+Orders 表
+
+```mysql
+create table orders
+(
+    id          int primary key auto_increment,
+    item_id     int,
+    amount      int,
+    unit_price  decimal(12, 4),
+    total       decimal(12, 4),
+    description varchar(2000),
+    ts          timestamp default now()
+);
+```
+
+记录了未完成的订单。审计部门现在需要记录其变更——新增或删除,该表不会发生update——即将修改都记录到 orders_log 表
+
+```mysql
+create table orders_log
+(
+    id          int primary key auto_increment,
+    item_id     int,
+    amount      int,
+    unit_price  decimal(12, 4),
+    total       decimal(12, 4),
+    description varchar(2000),
+    ts          timestamp,
+    direction   varchar(16),      
+    log_at      timestamp default now()
+);
+```
+
+那么应该如何做？
+
+## 答案
+
+```mysql
+create trigger in_orders after insert on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+    values(NEW.id, NEW.item_id, NEW.amount, NEW.unit_price, NEW.total, NEW.description, NEW.ts, 'in');
+
+create trigger out_orders after delete on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+                 values(OLD.id, OLD.item_id, OLD.amount, OLD.unit_price, OLD.total, OLD.description, OLD.ts, 'out');
+```
+
+## 选项
+
+### A
+
+```mysql
+create trigger in_orders after insert on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+    values(NEW.id, NEW.item_id, NEW.amount, NEW.unit_price, NEW.total, NEW.description, NEW.ts, 'in');
+
+```
+
+### B
+
+```mysql
+
+create trigger out_orders after delete on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+                 values(OLD.id, OLD.item_id, OLD.amount, OLD.unit_price, OLD.total, OLD.description, OLD.ts, 'out');
+```
+
+
+### C
+
+```mysql
+create trigger in_orders after insert on orders
+        for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+        values(NEW.id, NEW.item_id, NEW.amount, NEW.unit_price, NEW.total, NEW.description, NEW.ts, 'in');
+    after delete on orders
+        for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+                     values(OLD.id, OLD.item_id, OLD.amount, OLD.unit_price, OLD.total, OLD.description, OLD.ts, 'out');
+```
+
+### D
+
+```mysql
+create trigger in_orders after insert, after delete on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+    values(NEW.id, NEW.item_id, NEW.amount, NEW.unit_price, NEW.total, NEW.description, NEW.ts, 'in');
+```
\ No newline at end of file

gears/sql/trigger.sql

+create table orders_log
+(
+    event_id          int primary key auto_increment,
+    id int,
+    item_id     int,
+    amount      int,
+    unit_price  decimal(12, 4),
+    total       decimal(12, 4),
+    description varchar(2000),
+    ts          timestamp,
+    direction   varchar(16),
+    log_at      timestamp default now()
+);
+
+create trigger in_orders after insert on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+    values(NEW.id, NEW.item_id, NEW.amount, NEW.unit_price, NEW.total, NEW.description, NEW.ts, 'in');
+
+create trigger out_orders after delete on orders
+    for each row insert into orders_log(id, item_id, amount, unit_price, total, description, ts, direction)
+                 values(OLD.id, OLD.item_id, OLD.amount, OLD.unit_price, OLD.total, OLD.description, OLD.ts, 'out');
\ No newline at end of file