删除
原文：https://gorm.io/docs/delete.html
删除记录 Delete a Record
When deleting a record, the deleted value needs to have primary key or it will trigger a Batch Delete, for example:
当删除记录时，被删除的值需要有主键，否则会触发批量删除，例如：
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| // Email的ID是`10` Email's ID is `10`
db.Delete(&email)
// DELETE from emails where id = 10;
// 使用附加条件进行删除 Delete with additional conditions
db.Where("name = ?", "jinzhu").Delete(&email)
// DELETE from emails where id = 10 AND name = "jinzhu";
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使用主键删除 Delete with primary key
GORM allows to delete objects using primary key(s) with inline condition, it works with numbers, check out Query Inline Conditions for details
GORM允许使用内联条件和主键来删除对象，它适用于数字，查看查询内联条件以获取详细信息
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| db.Delete(&User{}, 10)
// DELETE FROM users WHERE id = 10;
db.Delete(&User{}, "10")
// DELETE FROM users WHERE id = 10;
db.Delete(&users, []int{1,2,3})
// DELETE FROM users WHERE id IN (1,2,3);
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删除钩子 Delete Hooks
GORM allows hooks BeforeDelete, AfterDelete, those methods will be called when deleting a record, refer Hooks for details
GORM允许在删除记录时调用钩子函数BeforeDelete，AfterDelete，这些方法将在删除记录时被调用，参考钩子以获取详细信息。
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| func (u *User) BeforeDelete(tx *gorm.DB) (err error) {
if u.Role == "admin" {
return errors.New("admin user not allowed to delete")
}
return
}
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批量删除 Batch Delete
The specified value has no primary value, GORM will perform a batch delete, it will delete all matched records
如果指定的值没有主键，GORM将执行批量删除，它将删除所有匹配的记录
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| 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%";
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To efficiently delete large number of records, pass a slice with primary keys to the Delete method.
要高效地删除大量记录，请将具有主键的切片传递给Delete方法。
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| var users = []User{{ID: 1}, {ID: 2}, {ID: 3}}
db.Delete(&users)
// DELETE FROM users WHERE id IN (1,2,3);
db.Delete(&users, "name LIKE ?", "%jinzhu%")
// DELETE FROM users WHERE name LIKE "%jinzhu%" AND id IN (1,2,3);
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阻止全局删除 Block Global Delete
If you perform a batch delete without any conditions, GORM WON’T run it, and will return ErrMissingWhereClause error
如果你执行一个不带任何条件的批量删除，GORM不会运行它，并返回ErrMissingWhereClause错误
You have to use some conditions or use raw SQL or enable AllowGlobalUpdate mode, for example:
你必须使用一些条件或使用原始SQL或启用AllowGlobalUpdate模式，例如：
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| db.Delete(&User{}).Error // gorm.ErrMissingWhereClause
db.Delete(&[]User{{Name: "jinzhu1"}, {Name: "jinzhu2"}}).Error // gorm.ErrMissingWhereClause
db.Where("1 = 1").Delete(&User{})
// DELETE FROM `users` WHERE 1=1
db.Exec("DELETE FROM users")
// DELETE FROM users
db.Session(&gorm.Session{AllowGlobalUpdate: true}).Delete(&User{})
// DELETE FROM users
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从已删除的行中返回数据 Returning Data From Deleted Rows
Return deleted data, only works for database support Returning, for example:
返回已删除的数据，仅适用于数据库支持Returning的情况，例如：
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| // return all columns
var users []User
DB.Clauses(clause.Returning{}).Where("role = ?", "admin").Delete(&users)
// DELETE FROM `users` WHERE role = "admin" RETURNING *
// users => []User{{ID: 1, Name: "jinzhu", Role: "admin", Salary: 100}, {ID: 2, Name: "jinzhu.2", Role: "admin", Salary: 1000}}
// return specified columns
DB.Clauses(clause.Returning{Columns: []clause.Column{{Name: "name"}, {Name: "salary"}}}).Where("role = ?", "admin").Delete(&users)
// DELETE FROM `users` WHERE role = "admin" RETURNING `name`, `salary`
// users => []User{{ID: 0, Name: "jinzhu", Role: "", Salary: 100}, {ID: 0, Name: "jinzhu.2", Role: "", Salary: 1000}}
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软删除 Soft Delete
If your model includes a gorm.DeletedAt field (which is included in gorm.Model), it will get soft delete ability automatically!
如果模型包含gorm.DeletedAt字段（包含在gorm.Model中），它将自动获得软删除能力！
When calling Delete, the record WON’T be removed from the database, but GORM will set the DeletedAt‘s value to the current time, and the data is not findable with normal Query methods anymore.
当调用Delete时，记录将不会被从数据库中删除，但GORM将设置DeletedAt的值当前时间，并且通过正常的查询方法无法找到数据。
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| // user's ID is `111`
db.Delete(&user)
// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE id = 111;
// Batch Delete
db.Where("age = ?", 20).Delete(&User{})
// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE age = 20;
// Soft deleted records will be ignored when querying
db.Where("age = 20").Find(&user)
// SELECT * FROM users WHERE age = 20 AND deleted_at IS NULL;
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If you don’t want to include gorm.Model, you can enable the soft delete feature like:
如果你不想包含gorm.Model，你可以像下面这样启用软删除功能：
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| type User struct {
ID int
Deleted gorm.DeletedAt
Name string
}
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查找已软删除的记录 Find soft deleted records
You can find soft deleted records with Unscoped
你可以使用Unscoped查找软删除的记录
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| db.Unscoped().Where("age = 20").Find(&users)
// SELECT * FROM users WHERE age = 20;
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永久删除 Delete permanently
You can delete matched records permanently with Unscoped
你可以永久删除匹配的记录，使用Unscoped
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| db.Unscoped().Delete(&order)
// DELETE FROM orders WHERE id=10;
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删除标志 Delete Flag
By default, gorm.Model uses *time.Time as the value for the DeletedAt field, and it provides other data formats support with plugin gorm.io/plugin/soft_delete
默认情况下，gorm.Model使用*time.Time作为DeletedAt字段的值，并提供了其他数据格式支持，使用插件gorm.io/plugin/soft_delete
INFO when creating unique composite index for the DeletedAt field, you must use other data format like unix second/flag with plugin gorm.io/plugin/soft_delete‘s help, e.g:
INFO 创建唯一复合索引以DeletedAt字段时，您必须使用其他数据格式，如使用插件gorm.io/plugin/soft_delete的帮助，例如：
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| import "gorm.io/plugin/soft_delete"
type User struct {
ID uint
Name string `gorm:"uniqueIndex:udx_name"`
DeletedAt soft_delete.DeletedAt `gorm:"uniqueIndex:udx_name"`
}
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Unix Second
Use unix second as delete flag
使用 Unix 秒数作为删除标记
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| import "gorm.io/plugin/soft_delete"
type User struct {
ID uint
Name string
DeletedAt soft_delete.DeletedAt
}
// 查询 Query
SELECT * FROM users WHERE deleted_at = 0;
// 删除 Delete
UPDATE users SET deleted_at = /* current unix second */ WHERE ID = 1;
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You can also specify to use milli or nano seconds as the value, for example:
你也可以指定使用 milli 或 nano 秒作为值，例如：
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| type User struct {
ID uint
Name string
DeletedAt soft_delete.DeletedAt `gorm:"softDelete:milli"`
// DeletedAt soft_delete.DeletedAt `gorm:"softDelete:nano"`
}
// Query
SELECT * FROM users WHERE deleted_at = 0;
// Delete
UPDATE users SET deleted_at = /* current unix milli second or nano second */ WHERE ID = 1;
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使用 1 / 0 作为删除标记 Use 1 / 0 AS Delete Flag
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| import "gorm.io/plugin/soft_delete"
type User struct {
ID uint
Name string
IsDel soft_delete.DeletedAt `gorm:"softDelete:flag"`
}
// 查询 Query
SELECT * FROM users WHERE is_del = 0;
// 删除 Delete
UPDATE users SET is_del = 1 WHERE ID = 1;
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混合模式 Mixed Mode
Mixed mode can use 0, 1 or unix seconds to mark data as deleted or not, and save the deleted time at the same time.
混合模式可以使用 0、1 或 Unix 秒数来标记数据是否已删除，并同时保存删除时间。
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| type User struct {
ID uint
Name string
DeletedAt time.Time
IsDel soft_delete.DeletedAt `gorm:"softDelete:flag,DeletedAtField:DeletedAt"` // use `1` `0`
// IsDel soft_delete.DeletedAt `gorm:"softDelete:,DeletedAtField:DeletedAt"` // use `unix second`
// IsDel soft_delete.DeletedAt `gorm:"softDelete:nano,DeletedAtField:DeletedAt"` // use `unix nano second`
}
// 查询 Query
SELECT * FROM users WHERE is_del = 0;
// 删除 Delete
UPDATE users SET is_del = 1, deleted_at = /* current unix second */ WHERE ID = 1;
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