1. 删除

1.1. 删除记录

警告：当删除一条记录的时候，你需要确定这条记录的主键有值，GORM会使用主键来删除这条记录。如果主键字段为空，GORM会删除模型中所有的记录。

// 删除一条存在的记录
db.Delete(&email)
//// DELETE from emails where id=10;

// 为删除 SQL 语句添加额外选项
db.Set("gorm:delete_option", "OPTION (OPTIMIZE FOR UNKNOWN)").Delete(&email)
//// DELETE from emails where id=10 OPTION (OPTIMIZE FOR UNKNOWN);

1.2. 批量删除

删除所有匹配的记录

db.Where("email LIKE ?", "%jinzhu%").Delete(Email{})
//// DELETE from emails where email LIKE "%jinzhu%";

db.Delete(Email{}, "email LIKE ?", "%jinzhu%")
//// DELETE from emails where email LIKE "%jinzhu%";

1.3. 软删除

如果模型中有 DeletedAt 字段，它将自动拥有软删除的能力！当执行删除操作时，数据并不会永久的从数据库中删除，而是将 DeletedAt 的值更新为当前时间。

db.Delete(&user)
//// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE id = 111;

// 批量删除
db.Where("age = ?", 20).Delete(&User{})
//// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE age = 20;

// 在查询记录时，软删除记录会被忽略
db.Where("age = 20").Find(&user)
//// SELECT * FROM users WHERE age = 20 AND deleted_at IS NULL;

// 使用 Unscoped 方法查找软删除记录
db.Unscoped().Where("age = 20").Find(&users)
//// SELECT * FROM users WHERE age = 20;

// 使用 Unscoped 方法永久删除记录
db.Unscoped().Delete(&order)
//// DELETE FROM orders WHERE id=10;