Sqlx library usage

Introduce

sqlx Is based on Go built-in database/sql Extensions on packages , Mainly to simplify sql Process of use , sqlx Of sql.DB, sql.TX, sql.Stmt Keep the underlying implementation unchanged , Therefore, it can be easily from database/sql Switch to sqlx.sqlx In addition, it also provides some functions ：

• Can be Rows The content is parsed to struct（ Support embedded ）、map、slice
• Named parameters support
• Get/Select You can quickly turn the query results into struct/slice

Installation and connection

go get github.com/jmoiron/sqlx

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import (
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
)

func main(){
  // Connect to database 
	//  Only  sqlx.Open()  Function to create a connection pool , At this time, only the connection pool is initialized , No connection to database .
    //  Connections are inert , Only a call  sqlx.DB  Method time ,
	//  At this time, the connection is really used , The connection pool will create connections .
	DB, err := sqlx.Open("mysql", "root:[email protected]@tcp(127.0.0.1:3306)/test?charset=utf8")
	if err != nil {
		fmt.Println("connect error：", err)
	}
	defer DB.Close()

	err = DB.Ping()
	if err != nil {
		fmt.Println("connect ping error：", err)
	}

	//  Connection pool configuration 
	DB.SetMaxIdleConns(100)
	DB.SetMaxOpenConns(500)
	DB.SetConnMaxIdleTime(5*time.Minute) 
}

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Table and table instance definitions

CREATE TABLE `person` (
		`first_name` text,
		`last_name` text,
		`email` text,
		`id` int NOT NULL AUTO_INCREMENT,
		PRIMARY KEY (`id`)
	) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8mb4;

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// Person  User information sheet 
type Person struct {
	Id        int
	FirstName string `db:"first_name"`
	LastName  string `db:"last_name"`
	Email     string `db:"email"`
}

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The insert ( Single / Batch insert )

	sqlStr := "insert into person(first_name, last_name, email) values (?,?,?)"
	ret, err := DB.Exec(sqlStr, "Jason", "Moron", "[email protected]")
	if err != nil {
		fmt.Println(" Error inserting ", err)
		return
	}
	theID, err := ret.LastInsertId() //  Newly inserted data id
	if err != nil {
		fmt.Println(" Get inserted id error ：", err)
		return
	}
	fmt.Println(" Insert the success ,id by ：", theID)

	ret, err = DB.NamedExec("INSERT INTO person (first_name, last_name, email) 		  VALUES (:first_name, :last_name, :email)",
		&Person{FirstName: "Jane", LastName: "Citizen", 
		Email: "[email protected]"})
	if err != nil {
		fmt.Println(" Error inserting ", err)
		return
	}
	theID, err = ret.LastInsertId() //  Newly inserted data id
	if err != nil {
		fmt.Println(" Get inserted id error ：", err)
		return
	}
	fmt.Println(" Insert the success ,id by ：", theID)

	// batch insert with structs
	personStructs := []Person{
		{FirstName: "Ardie0", LastName: "Savea", Email: "[email protected]"},
		{FirstName: "Sonny Bill0", LastName: "Williams", Email: "[email protected]"},
		{FirstName: "Ngani0", LastName: "Laumape", Email: "[email protected]"},
	}

	ret, err = DB.NamedExec(`INSERT INTO person (first_name, last_name, email)
        VALUES (:first_name, :last_name, :email)`, personStructs)
	if err != nil {
		fmt.Println(" Batch insert error ", err)
		return
	}

	affectRows, err := ret.RowsAffected()
	fmt.Printf("affect rows:%d, err=%v \n", affectRows, err)

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The transaction operations

	// batch insert with maps
	personMaps := []map[string]interface{}{
		{"first_name": "Ardie1", "last_name": "Savea", 
		"email": "[email protected]"},
		{"first_name": "Sonny Bill1", "last_name": "Williams", 
		"email": "[email protected]"},
		{"first_name": "Ngani1", "last_name": "Laumape", 
		"email": "[email protected]"},
	}
	//  Open transaction 
	tx, err := DB.Beginx()
	_, err = tx.NamedExec(`INSERT INTO person (first_name, last_name, email)
        VALUES (:first_name, :last_name, :email)`, personMaps)
	if err != nil {
		//  Roll back if an error occurs 
		tx.Rollback()
		fmt.Println(" Batch insert error ", err)
		return
	}
	tx.Commit()
	

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Query operation ( Single / Multiple records query )

	
	// 2.  Query data 
	sqlStr = "SELECT * FROM person WHERE last_name=:last_name"
	//  Use map Make a named query 
	rows, _ := DB.NamedQuery(sqlStr, map[string]interface{}{"last_name": "Savea"})
	defer rows.Close()
	for rows.Next() {
		var m Person
		rows.StructScan(&m)
		fmt.Println(m)
	}
	
	//  Use structure to make naming query 
	var person = Person{LastName: "Savea"}
	rows, _ = DB.NamedQuery(sqlStr, person)
	defer rows.Close()
	for rows.Next() {
		var p Person
		rows.StructScan(&p)
		fmt.Println(p)
	}

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Get/Select operation

	
	// Get  Inquire about 
	var personGet Person
	err = DB.Get(&personGet, "select * from person where id=?", 1)
	if err != nil {
		fmt.Println(" Query error ", err)
	}
	fmt.Println(personGet)
	
	// Select  Inquire about 
	var persons []Person
	err = DB.Select(&persons, "select * from person where id > ?", 1)
	if err != nil {
		fmt.Println(" Query error ", err)
	}
	fmt.Println(persons)

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Update data

	// 3  Modifying data 
	sqlStr = "update person set last_name= ? where id = ?"
	ret, err = DB.Exec(sqlStr, "Savea", 1)
	if err != nil {
		fmt.Println(" Update failed ", err)
		return
	}
	n, err := ret.RowsAffected()
	if err != nil {
		fmt.Println(" Failed to get the number of affected rows ：", err)
		return
	}
	fmt.Println(" The update is successful , The number of affected lines is ：", n)

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Delete data

	sqlStr = "delete from person where id = ?"
	ret, err = DB.Exec(sqlStr, 1)
	if err != nil {
		fmt.Println(" Error deleting ：", err)
		return
	}
	n, err = ret.RowsAffected() //  Number of rows affected by operation 
	if err != nil {
		fmt.Println(" Error getting the number of rows affected by the operation ：", err)
		return
	}
	fmt.Println(" Delete successful , The number of rows affected is ：", n)

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