gormExample/session.go

package gormExample

import (
	"fmt"
	"gorm.io/gorm"
	"log"
)

func SessionIssue() {
	// 连续控制条件
	//db := DB.Model(&Content{}).Where("views > ?", 100)
	//db.Where("likes > ?", 9)
	//var cs []Content
	//db.Find(&cs)
	// [4.319ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes > 9 AND `msb_content`.`deleted_at` IS NULL

	// 连续执行查询
	// 1
	// Where("views > ?", 100).Where("likes > ?", 9)
	db := DB.Model(&Content{}).Where("views > ?", 100)

	db.Where("likes > ?", 9)
	var cs1 []Content
	db.Find(&cs1)
	// [10.566ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes > 9 AND `msb_content`.`deleted_at` IS NULL

	// 2,找到likes<5
	// Where("views > ?", 100).Where("likes < ?", 5)
	db.Where("likes < ?", 5)
	var cs2 []Content
	db.Find(&cs2)
	// [2.815ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes > 9 AND `msb_content`.`deleted_at` IS NULL AND likes < 5
}

func SessionDB() {
	// 连续执行查询
	// 1
	// Where("views > ?", 100).Where("likes > ?", 9)
	db1 := DB.Model(&Content{}).Where("views > ?", 100)
	db1.Where("likes > ?", 9)
	var cs1 []Content
	db1.Find(&cs1)
	// [10.683ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes > 9 AND `msb_content`.`deleted_at` IS NULL

	// 2,找到likes<5
	// Where("views > ?", 100).Where("likes < ?", 5)
	db2 := DB.Model(&Content{}).Where("views > ?", 100)
	db2.Where("likes < ?", 5)
	var cs2 []Content
	db2.Find(&cs2)
	// [4.139ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes < 5 AND `msb_content`.`deleted_at` IS NULL
}

func SessionNew() {

	// 需要重复使用的部分
	// 将Session方法前的配置，记录到了当前的会话中
	// 后边再次调用db的方法直到终结方法，会保持会话中的子句选项
	// 执行完终结方法后，再次调用db的方法到终结方法，可以重用会话中的子句选项。
	db := DB.Model(&Content{}).Where("views > ?", 100).Session(&gorm.Session{})

	// 连续执行查询
	// 1
	// Where("views > ?", 100).Where("likes > ?", 9)
	var cs1 []Content
	db.Where("likes > ?", 9).Find(&cs1)
	// [4.633ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes > 9 AND `msb_content`.`deleted_at` IS NULL

	// 2,找到likes<5
	// Where("views > ?", 100).Where("likes < ?", 5)
	var cs2 []Content
	db.Where("likes < ?", 5).Find(&cs2)
	// [3.846ms] [rows:0] SELECT * FROM `msb_content` WHERE views > 100 AND likes < 5 AND `msb_content`.`deleted_at` IS NULL
}
func SessionOptions() {
	// Skip Hook
	//db := DB.Session(&gorm.Session{
	//	SkipHooks: true,
	//})
	//db.Save(&Content{Subject: "no create hook"})

	// DryRun
	//db := DB.Session(&gorm.Session{
	//	DryRun: true,
	//})
	//stmt := db.Save(&Content{}).Statement
	//fmt.Println(stmt.SQL.String())
	//// INSERT INTO `msb_content` (`created_at`,`updated_at`,`deleted_at`,`subject`,`likes`,`views`,`publish_time`,`author_id`) VALUES (?,?,?,?,?,?,?,?) ON DUPLICATE KEY UPDATE `updated_at`=?,`deleted_at`=VALUES(`deleted_at`),`subject`=VALUES(`subject`),`likes`=VALUES(`likes`),`views`=VALUES(`views`),`publish_time`=VALUES(`publish_time`),`author_id`=VALUES(`author_id`)
	//fmt.Println(stmt.Vars)
	//// [2023-04-24 17:25:47.827 +0800 CST 2023-04-24 17:25:47.827 +0800 CST {0001-01-01 00:00:00 +0000 UTC false}  0 0 2023-04-24 17:25:47.823908 +0800 CST 0 2023-04-24 17:25:47.827 +0800 CST]

	// Debug
	//DB.Debug().First()

	// prepare 预编译，编译重用，编译独立
	// SQL, 编译，绑定数据，执行
	// 预编译，将编译的过程缓存起来，便于重用。
	// 在执行结构相同的SQL时，可以重用。
	db := DB.Session(&gorm.Session{
		PrepareStmt: true,
	})

	// 预编译管理对象
	stmtManager, ok := db.ConnPool.(*gorm.PreparedStmtDB)
	if !ok {
		log.Fatalln("*gorm.PreparedStmtDB assert failed")
	}
	fmt.Println(stmtManager.PreparedSQL)
	fmt.Println(stmtManager.Stmts)

	var c1 Content
	db.First(&c1, 13)
	fmt.Println(stmtManager.PreparedSQL)
	fmt.Println(stmtManager.Stmts)
	// [SELECT * FROM `msb_content` WHERE `msb_content`.`id` = ? AND `msb_content`.`deleted_at` IS NULL ORDER BY `msb_content`.`id` LIMIT 1]
	// map[SELECT * FROM `msb_content` WHERE `msb_content`.`id` = ? AND `msb_content`.`deleted_at` IS NULL ORDER BY `msb_content`.`id` LIMIT 1:0xc0001cd920]

	var c2 Content
	db.First(&c2, 14)
	fmt.Println(stmtManager.PreparedSQL)
	fmt.Println(stmtManager.Stmts)
	// [SELECT * FROM `msb_content` WHERE `msb_content`.`id` = ? AND `msb_content`.`deleted_at` IS NULL ORDER BY `msb_content`.`id` LIMIT 1]
	// map[SELECT * FROM `msb_content` WHERE `msb_content`.`id` = ? AND `msb_content`.`deleted_at` IS NULL ORDER BY `msb_content`.`id` LIMIT 1:0xc0001cd920]

	var c3 []Content
	db.Find(&c3, []uint{15, 16})
	fmt.Println(stmtManager.PreparedSQL)
	fmt.Println(stmtManager.Stmts)
	//	[SELECT * FROM `msb_content` WHERE `msb_content`.`id` = ? AND `msb_content`.`deleted_at` IS NULL ORDER BY `msb_content`.`id` LIMIT 1 SELECT * FROM `msb_content` WHERE `msb_content`.`id` IN (?,?) AND `msb_content`.`deleted_at` IS NULL]
	// map[SELECT * FROM `msb_content` WHERE `msb_content`.`id` = ? AND `msb_content`.`deleted_at` IS NULL ORDER BY `msb_content`.`id` LIMIT 1:0xc0001cb920 SELECT * FROM `msb_content` WHERE `msb_content`.`id` IN (?,?) AND `msb_content`.`deleted_at` IS NULL:0xc0001cbe30]

}