# CRUD: Reading and Writing Data

<!-- toc -->

## Create

### Create Record

```go
user := User{Name: "Jinzhu", Age: 18, Birthday: time.Now()}

db.NewRecord(user) // => returns `true` as primary key is blank

db.Create(&user)

db.NewRecord(user) // => return `false` after `user` created

// Associations will be inserted automatically when save the record
user := User{
	Name:            "jinzhu",
	BillingAddress:  Address{Address1: "Billing Address - Address 1"},
	ShippingAddress: Address{Address1: "Shipping Address - Address 1"},
	Emails:          []Email{{Email: "jinzhu@example.com"}, {Email: "jinzhu-2@example@example.com"}},
	Languages:       []Language{{Name: "ZH"}, {Name: "EN"}},
}

db.Create(&user)
//// BEGIN TRANSACTION;
//// INSERT INTO "addresses" (address1) VALUES ("Billing Address - Address 1");
//// INSERT INTO "addresses" (address1) VALUES ("Shipping Address - Address 1");
//// INSERT INTO "users" (name,billing_address_id,shipping_address_id) VALUES ("jinzhu", 1, 2);
//// INSERT INTO "emails" (user_id,email) VALUES (111, "jinzhu@example.com");
//// INSERT INTO "emails" (user_id,email) VALUES (111, "jinzhu-2@example.com");
//// INSERT INTO "languages" ("name") VALUES ('ZH');
//// INSERT INTO user_languages ("user_id","language_id") VALUES (111, 1);
//// INSERT INTO "languages" ("name") VALUES ('EN');
//// INSERT INTO user_languages ("user_id","language_id") VALUES (111, 2);
//// COMMIT;
```

### Create With Associations

Refer [Associations](associations.html) for more details

### Default Values

You could define default value in the `gorm` tag, then the inserting SQL will ignore these fields that has default value and its value is blank, and after insert the record into databae, gorm will load those fields's value from database.

```go
type Animal struct {
	ID   int64
	Name string `gorm:"default:'galeone'"`
	Age  int64
}

var animal = Animal{Age: 99, Name: ""}
db.Create(&animal)
// INSERT INTO animals("age") values('99');
// SELECT name from animals WHERE ID=111; // the returning primary key is 111
// animal.Name => 'galeone'
```

### Setting Primary Key In Callbacks

If you want to set primary field's value in `BeforeCreate` callback, you could use `scope.SetColumn`, for example:

```go
func (user *User) BeforeCreate(scope *gorm.Scope) error {
  scope.SetColumn("ID", uuid.New())
  return nil
}
```

### Extra Creating option

```go
// Add extra SQL option for inserting SQL
db.Set("gorm:insert_option", "ON CONFLICT").Create(&product)
// INSERT INTO products (name, code) VALUES ("name", "code") ON CONFLICT;
```

## Query

```go
// Get first record, order by primary key
db.First(&user)
//// SELECT * FROM users ORDER BY id LIMIT 1;

// Get last record, order by primary key
db.Last(&user)
//// SELECT * FROM users ORDER BY id DESC LIMIT 1;

// Get all records
db.Find(&users)
//// SELECT * FROM users;

// Get record with primary key
db.First(&user, 10)
//// SELECT * FROM users WHERE id = 10;
```

### Query With Where (Plain SQL)

```go
// Get first matched record
db.Where("name = ?", "jinzhu").First(&user)
//// SELECT * FROM users WHERE name = 'jinzhu' limit 1;

// Get all matched records
db.Where("name = ?", "jinzhu").Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu';

db.Where("name <> ?", "jinzhu").Find(&users)

// IN
db.Where("name in (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users)

// LIKE
db.Where("name LIKE ?", "%jin%").Find(&users)

// AND
db.Where("name = ? AND age >= ?", "jinzhu", "22").Find(&users)

// Time
db.Where("updated_at > ?", lastWeek).Find(&users)

db.Where("created_at BETWEEN ? AND ?", lastWeek, today).Find(&users)
```

### Query With Where (Struct & Map)

**NOTE** When query with struct, GORM will only query with those fields has value

```go
// Struct
db.Where(&User{Name: "jinzhu", Age: 20}).First(&user)
//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20 LIMIT 1;

// Map
db.Where(map[string]interface{}{"name": "jinzhu", "age": 20}).Find(&users)
//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20;

// Slice of primary keys
db.Where([]int64{20, 21, 22}).Find(&users)
//// SELECT * FROM users WHERE id IN (20, 21, 22);
```

### Query With Not

```go
db.Not("name", "jinzhu").First(&user)
//// SELECT * FROM users WHERE name <> "jinzhu" LIMIT 1;

// Not In
db.Not("name", []string{"jinzhu", "jinzhu 2"}).Find(&users)
//// SELECT * FROM users WHERE name NOT IN ("jinzhu", "jinzhu 2");

// Not In slice of primary keys
db.Not([]int64{1,2,3}).First(&user)
//// SELECT * FROM users WHERE id NOT IN (1,2,3);

db.Not([]int64{}).First(&user)
//// SELECT * FROM users;

// Plain SQL
db.Not("name = ?", "jinzhu").First(&user)
//// SELECT * FROM users WHERE NOT(name = "jinzhu");

// Struct
db.Not(User{Name: "jinzhu"}).First(&user)
//// SELECT * FROM users WHERE name <> "jinzhu";
```

### Query With Inline Condition

**NOTE** When query with primary key, you should carefully check the value you passed is a valid primary key, to avoid SQL injection

```go
// Get by primary key
db.First(&user, 23)
//// SELECT * FROM users WHERE id = 23 LIMIT 1;

// Plain SQL
db.Find(&user, "name = ?", "jinzhu")
//// SELECT * FROM users WHERE name = "jinzhu";

db.Find(&users, "name <> ? AND age > ?", "jinzhu", 20)
//// SELECT * FROM users WHERE name <> "jinzhu" AND age > 20;

// Struct
db.Find(&users, User{Age: 20})
//// SELECT * FROM users WHERE age = 20;

// Map
db.Find(&users, map[string]interface{}{"age": 20})
//// SELECT * FROM users WHERE age = 20;
```

### Query With Or

```go
db.Where("role = ?", "admin").Or("role = ?", "super_admin").Find(&users)
//// SELECT * FROM users WHERE role = 'admin' OR role = 'super_admin';

// Struct
db.Where("name = 'jinzhu'").Or(User{Name: "jinzhu 2"}).Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2';

// Map
db.Where("name = 'jinzhu'").Or(map[string]interface{}{"name": "jinzhu 2"}).Find(&users)
```

### Query Chains

Gorm has a chainable API, you could use it like this

```go
db.Where("name <> ?","jinzhu").Where("age >= ? and role <> ?",20,"admin").Find(&users)
//// SELECT * FROM users WHERE name <> 'jinzhu' AND age >= 20 AND role <> 'admin';

db.Where("role = ?", "admin").Or("role = ?", "super_admin").Not("name = ?", "jinzhu").Find(&users)
```

### Extra Querying option

```go
// Add extra SQL option for selecting SQL
db.Set("gorm:query_option", "FOR UPDATE").First(&user, 10)
//// SELECT * FROM users WHERE id = 10 FOR UPDATE;
```

### FirstOrInit

Get first matched record, or initalize a new one with given conditions (only works with struct, map conditions)

```go
// Unfound
db.FirstOrInit(&user, User{Name: "non_existing"})
//// user -> User{Name: "non_existing"}

// Found
db.Where(User{Name: "Jinzhu"}).FirstOrInit(&user)
//// user -> User{Id: 111, Name: "Jinzhu", Age: 20}
db.FirstOrInit(&user, map[string]interface{}{"name": "jinzhu"})
//// user -> User{Id: 111, Name: "Jinzhu", Age: 20}
```

#### Attrs

Initalize struct with argument if record haven't been found

```go
// Unfound
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = 'non_existing';
//// user -> User{Name: "non_existing", Age: 20}

db.Where(User{Name: "noexisting_user"}).Attrs("age", 20).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = 'non_existing';
//// user -> User{Name: "non_existing", Age: 20}

// Found
db.Where(User{Name: "Jinzhu"}).Attrs(User{Age: 30}).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = jinzhu';
//// user -> User{Id: 111, Name: "Jinzhu", Age: 20}
```

#### Assign

Assign argument to results regardless it is found or not

```go
// Unfound
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrInit(&user)
//// user -> User{Name: "non_existing", Age: 20}

// Found
db.Where(User{Name: "Jinzhu"}).Assign(User{Age: 30}).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = jinzhu';
//// user -> User{Id: 111, Name: "Jinzhu", Age: 30}
```

### FirstOrCreate

Get first matched record, or create a new one with given conditions (only works with struct, map conditions)

```go
// Unfound
db.FirstOrCreate(&user, User{Name: "non_existing"})
//// INSERT INTO "users" (name) VALUES ("non_existing");
//// user -> User{Id: 112, Name: "non_existing"}

// Found
db.Where(User{Name: "Jinzhu"}).FirstOrCreate(&user)
//// user -> User{Id: 111, Name: "Jinzhu"}
```

#### Attrs

Assgin struct with argument if record haven't been found

```go
// Unfound
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrCreate(&user)
//// SELECT * FROM users WHERE name = 'non_existing';
//// INSERT INTO "users" (name, age) VALUES ("non_existing", 20);
//// user -> User{Id: 112, Name: "non_existing", Age: 20}

// Found
db.Where(User{Name: "jinzhu"}).Attrs(User{Age: 30}).FirstOrCreate(&user)
//// SELECT * FROM users WHERE name = 'jinzhu';
//// user -> User{Id: 111, Name: "jinzhu", Age: 20}
```

#### Assign

Assign it to the record regardless it is found or not, and save back to database.

```go
// Unfound
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrCreate(&user)
//// SELECT * FROM users WHERE name = 'non_existing';
//// INSERT INTO "users" (name, age) VALUES ("non_existing", 20);
//// user -> User{Id: 112, Name: "non_existing", Age: 20}

// Found
db.Where(User{Name: "jinzhu"}).Assign(User{Age: 30}).FirstOrCreate(&user)
//// SELECT * FROM users WHERE name = 'jinzhu';
//// UPDATE users SET age=30 WHERE id = 111;
//// user -> User{Id: 111, Name: "jinzhu", Age: 30}
```

### Select

Specify fields that you want to retrieve from database, by default, will select all fields;

```go
db.Select("name, age").Find(&users)
//// SELECT name, age FROM users;

db.Select([]string{"name", "age"}).Find(&users)
//// SELECT name, age FROM users;

db.Table("users").Select("COALESCE(age,?)", 42).Rows()
//// SELECT COALESCE(age,'42') FROM users;
```

### Order

Specify order when retrieve records from database, set reorder to `true` to overwrite defined conditions

```go
db.Order("age desc, name").Find(&users)
//// SELECT * FROM users ORDER BY age desc, name;

// Multiple orders
db.Order("age desc").Order("name").Find(&users)
//// SELECT * FROM users ORDER BY age desc, name;

// ReOrder
db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
//// SELECT * FROM users ORDER BY age desc; (users1)
//// SELECT * FROM users ORDER BY age; (users2)
```

### Limit

Specify the number of records to be retrieved

```go
db.Limit(3).Find(&users)
//// SELECT * FROM users LIMIT 3;

// Cancel limit condition with -1
db.Limit(10).Find(&users1).Limit(-1).Find(&users2)
//// SELECT * FROM users LIMIT 10; (users1)
//// SELECT * FROM users; (users2)
```

### Offset

Specify the number of records to skip before starting to return the records

```go
db.Offset(3).Find(&users)
//// SELECT * FROM users OFFSET 3;

// Cancel offset condition with -1
db.Offset(10).Find(&users1).Offset(-1).Find(&users2)
//// SELECT * FROM users OFFSET 10; (users1)
//// SELECT * FROM users; (users2)
```

### Count

Get how many records for a model

```go
db.Where("name = ?", "jinzhu").Or("name = ?", "jinzhu 2").Find(&users).Count(&count)
//// SELECT * from USERS WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (users)
//// SELECT count(*) FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (count)

db.Model(&User{}).Where("name = ?", "jinzhu").Count(&count)
//// SELECT count(*) FROM users WHERE name = 'jinzhu'; (count)

db.Table("deleted_users").Count(&count)
//// SELECT count(*) FROM deleted_users;
```

### Group & Having

```go
rows, err := db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Rows()
for rows.Next() {
	...
}

rows, err := db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Having("sum(amount) > ?", 100).Rows()
for rows.Next() {
	...
}

type Result struct {
	Date  time.Time
	Total int64
}
db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Having("sum(amount) > ?", 100).Scan(&results)
```

### Joins

Specify Joins conditions

```go
rows, err := db.Table("users").Select("users.name, emails.email").Joins("left join emails on emails.user_id = users.id").Rows()
for rows.Next() {
	...
}

db.Table("users").Select("users.name, emails.email").Joins("left join emails on emails.user_id = users.id").Scan(&results)

// multiple joins with parameter
db.Joins("JOIN emails ON emails.user_id = users.id AND emails.email = ?", "jinzhu@example.org").Joins("JOIN credit_cards ON credit_cards.user_id = users.id").Where("credit_cards.number = ?", "411111111111").Find(&user)
```

### Pluck

Query single column from a model as a map, if you want to query multiple columns, you could use [`Scan`](#scan)

```go
var ages []int64
db.Find(&users).Pluck("age", &ages)

var names []string
db.Model(&User{}).Pluck("name", &names)

db.Table("deleted_users").Pluck("name", &names)

// Requesting more than one column? Do it like this:
db.Select("name, age").Find(&users)
```

### Scan

Scan results into another struct.

```go
type Result struct {
	Name string
	Age  int
}

var result Result
db.Table("users").Select("name, age").Where("name = ?", 3).Scan(&result)

// Raw SQL
db.Raw("SELECT name, age FROM users WHERE name = ?", 3).Scan(&result)
```

### Scopes

Pass current database connection to `func(*DB) *DB`, which could be used to add conditions dynamically

```go
func AmountGreaterThan1000(db *gorm.DB) *gorm.DB {
	return db.Where("amount > ?", 1000)
}

func PaidWithCreditCard(db *gorm.DB) *gorm.DB {
	return db.Where("pay_mode_sign = ?", "C")
}

func PaidWithCod(db *gorm.DB) *gorm.DB {
	return db.Where("pay_mode_sign = ?", "C")
}

func OrderStatus(status []string) func (db *gorm.DB) *gorm.DB {
	return func (db *gorm.DB) *gorm.DB {
		return db.Scopes(AmountGreaterThan1000).Where("status in (?)", status)
	}
}

db.Scopes(AmountGreaterThan1000, PaidWithCreditCard).Find(&orders)
// Find all credit card orders and amount greater than 1000

db.Scopes(AmountGreaterThan1000, PaidWithCod).Find(&orders)
// Find all COD orders and amount greater than 1000

db.Scopes(OrderStatus([]string{"paid", "shipped"})).Find(&orders)
// Find all paid, shipped orders
```

### Specifying The Table Name

```go
// Create `deleted_users` table with struct User's definition
db.Table("deleted_users").CreateTable(&User{})

var deleted_users []User
db.Table("deleted_users").Find(&deleted_users)
//// SELECT * FROM deleted_users;

db.Table("deleted_users").Where("name = ?", "jinzhu").Delete()
//// DELETE FROM deleted_users WHERE name = 'jinzhu';
```

## Update

### Update All Fields

`Save` will include all fields when perform the Updating SQL, even it is not changed

```go
db.First(&user)

user.Name = "jinzhu 2"
user.Age = 100
db.Save(&user)

//// UPDATE users SET name='jinzhu 2', age=100, birthday='2016-01-01', updated_at = '2013-11-17 21:34:10' WHERE id=111;
```

### Update Changed Fields

If you only want to update changed Fields, you could use `Update`, `Updates`

```go
// Update single attribute if it is changed
db.Model(&user).Update("name", "hello")
//// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111;

// Update single attribute with combined conditions
db.Model(&user).Where("active = ?", true).Update("name", "hello")
//// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111 AND active=true;

// Update multiple attributes with `map`, will only update those changed fields
db.Model(&user).Updates(map[string]interface{}{"name": "hello", "age": 18, "actived": false})
//// UPDATE users SET name='hello', age=18, actived=false, updated_at='2013-11-17 21:34:10' WHERE id=111;

// Update multiple attributes with `struct`, will only update those changed & non blank fields
db.Model(&user).Updates(User{Name: "hello", Age: 18})
//// UPDATE users SET name='hello', age=18, updated_at = '2013-11-17 21:34:10' WHERE id = 111;

// WARNING when update with struct, GORM will only update those fields that with non blank value
// For below Update, nothing will be updated as "", 0, false are blank values of their types
db.Model(&user).Updates(User{Name: "", Age: 0, Actived: false})
```

### Update Selected Fields

If you only want to update or ignore some fields when updating, you could use `Select`, `Omit`

```go
db.Model(&user).Select("name").Updates(map[string]interface{}{"name": "hello", "age": 18, "actived": false})
//// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111;

db.Model(&user).Omit("name").Updates(map[string]interface{}{"name": "hello", "age": 18, "actived": false})
//// UPDATE users SET age=18, actived=false, updated_at='2013-11-17 21:34:10' WHERE id=111;
```

### Update Changed Fields Without Callbacks

Above updating operations will perform the mdoel's `BeforeUpdate`, `AfterUpdate` method, update its `UpdatedAt` timestamp, save its `Associations` when updaing, if you don't want to call them, you could use `UpdateColumn`, `UpdateColumns`

```go
// Update single attribute, similar with `Update`
db.Model(&user).UpdateColumn("name", "hello")
//// UPDATE users SET name='hello' WHERE id = 111;

// Update multiple attributes, similar with `Updates`
db.Model(&user).UpdateColumns(User{Name: "hello", Age: 18})
//// UPDATE users SET name='hello', age=18 WHERE id = 111;
```

### Batch Updates

Callbacks won't run when do batch updates

```go
db.Table("users").Where("id IN (?)", []int{10, 11}).Updates(map[string]interface{}{"name": "hello", "age": 18})
//// UPDATE users SET name='hello', age=18 WHERE id IN (10, 11);

// Update with struct only works with none zero values, or use map[string]interface{}
db.Model(User{}).Updates(User{Name: "hello", Age: 18})
//// UPDATE users SET name='hello', age=18;

// Get updated records count with `RowsAffected`
db.Model(User{}).Updates(User{Name: "hello", Age: 18}).RowsAffected
```

### Update with SQL Expression

```go
DB.Model(&product).Update("price", gorm.Expr("price * ? + ?", 2, 100))
//// UPDATE "products" SET "price" = price * '2' + '100', "updated_at" = '2013-11-17 21:34:10' WHERE "id" = '2';

DB.Model(&product).Updates(map[string]interface{}{"price": gorm.Expr("price * ? + ?", 2, 100)})
//// UPDATE "products" SET "price" = price * '2' + '100', "updated_at" = '2013-11-17 21:34:10' WHERE "id" = '2';

DB.Model(&product).UpdateColumn("quantity", gorm.Expr("quantity - ?", 1))
//// UPDATE "products" SET "quantity" = quantity - 1 WHERE "id" = '2';

DB.Model(&product).Where("quantity > 1").UpdateColumn("quantity", gorm.Expr("quantity - ?", 1))
//// UPDATE "products" SET "quantity" = quantity - 1 WHERE "id" = '2' AND quantity > 1;
```

### Change Updating Values In Callbacks

If you want to change updating values in callbacks using `BeforeUpdate`, `BeforeSave`, you could use `scope.SetColumn`, for example:

```go
func (user *User) BeforeSave(scope *gorm.Scope) (err error) {
  if pw, err := bcrypt.GenerateFromPassword(user.Password, 0); err == nil {
    scope.SetColumn("EncryptedPassword", pw)
  }
}
```

### Extra Updating option

```go
// Add extra SQL option for updating SQL
db.Model(&user).Set("gorm:update_option", "OPTION (OPTIMIZE FOR UNKNOWN)").Update("name, "hello")
//// UPDATE users SET name='hello', updated_at = '2013-11-17 21:34:10' WHERE id=111 OPTION (OPTIMIZE FOR UNKNOWN);
```

## Delete

**WARNING** When delete a record, you need to ensure it's primary field has value, and GORM will use the primary key to delete the record, if primary field's blank, GORM will delete all records for the model

```go
// Delete an existing record
db.Delete(&email)
//// DELETE from emails where id=10;

// Add extra SQL option for deleting SQL
db.Set("gorm:delete_option", "OPTION (OPTIMIZE FOR UNKNOWN)").Delete(&email)
//// DELETE from emails where id=10 OPTION (OPTIMIZE FOR UNKNOWN);
```

### Batch Delete

Delete all matched records

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

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

### Soft Delete

If model has `DeletedAt` field, it will get soft delete ability automatically! then it won't be deleted from database permanently when call `Delete`, but only set field `DeletedAt`'s value to current time

```go
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 query them
db.Where("age = 20").Find(&user)
//// SELECT * FROM users WHERE age = 20 AND deleted_at IS NULL;

// Find soft deleted records with Unscoped
db.Unscoped().Where("age = 20").Find(&users)
//// SELECT * FROM users WHERE age = 20;

// Delete record permanently with Unscoped
db.Unscoped().Delete(&order)
//// DELETE FROM orders WHERE id=10;
```