插入测试数据

---

package main

import (
	"fmt"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type Student struct {
	ID    int64
	Name  string `gorm:"size:6"`
	Age   int
	Email *string
}

func (*Student) TableName() string {
	return "student"
}

func main() {
	dsn := "root:7PXjAkY!&nlR@tcp(192.168.11.128:3306)/test?charset=utf8mb4&parseTime=True&loc=Local"
	db, _ := gorm.Open(mysql.Open(dsn), &gorm.Config{})
	db.AutoMigrate(&Student{})

	var sList []Student
	count := db.Find(&sList).Delete(&sList).RowsAffected
	fmt.Println("count=", count)
	email1 := "12396836709@qq.com"

	sList = []Student{
		{
			ID:    1,
			Name:  "lucas",
			Age:   30,
			Email: &email1,
		},
		{
			ID:    2,
			Name:  "yanzi",
			Age:   28,
			Email: &email1,
		},
		{
			ID:    3,
			Name:  "lulei",
			Age:   29,
			Email: &email1,
		},
		{
			ID:    4,
			Name:  "jerry",
			Age:   25,
			Email: &email1,
		},
	}
	db.Create(&sList)

}

Where语句里面条件    where + find = select * from table where...........

---

其实就是sql语句当中的where 

	var sList []Student
	db.Debug().Where("name = ?", "lucas").Find(&sList)
	fmt.Println(sList)

[0.746ms] [rows:1] SELECT * FROM `student` WHERE name = 'lucas'
[{1 lucas 30 0xc0001c91f0}] 



    var s Student
	db.Debug().Where("name = ?", "yanzi").First(&s)
	fmt.Println(s)

[1.263ms] [rows:1] SELECT * FROM `student` WHERE name = 'yanzi' ORDER BY `student`.`id` LIMIT 1
{2 yanzi 18 <nil>}

之前学的这种写法也是可以的 

	var s Student
	db.Debug().Find(&s, "name = ?", "lucas")
	fmt.Println(s)

[1.552ms] [rows:1] SELECT * FROM `student` WHERE name = 'lucas'              
{1 lucas 30 0xc0001c9300}  

使用结构体查询

---

如果是零值，那么查询的时候就不会将零值作为查询带上了 

	s = Student{
		Name: "lucas",
		Age:  30,
	}
	db.Debug().Where(&s).Find(&s)

[1.543ms] [rows:1] SELECT * FROM `student` WHERE `student`.`name` = 'lucas' AND `student`.`age` = 30