Getting started with Go Mysql and Redis

Posted by programguru on Sat, 11 Apr 2020 16:17:34 +0200

Mysql and Redis operations

Mysql development

Install mysql and create test library
Create table

mysql> CREATE TABLE `user` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `name` varchar(20) DEFAULT '', `age` int(11) DEFAULT '0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4;
mysql> insert into user (name,age)values('jim',18)

SQL query

Single line query: Db.QueryRole
Multiline query: Db.Query

import (
   "fmt"
   _"github.com/go-sql-driver/mysql"
   "database/sql"
)

type User struct {
   Id   int64     `db:"id"`
   Name string    `db:"name"`
   Age  int       `db:"age"`
}

func connMysql() {
   dns := "root:123456@tcp(localhost:3306)/test"
   conn,err := sql.Open("mysql",dns)
   if err != nil {
      fmt.Printf("connect mysql err:%v\n",err)
      return
   }

   err = conn.Ping()

   if err != nil {
      fmt.Printf("ping faild,err :%v\n",err)
   }

   fmt.Printf("connect mysql successfully!\n")
   QueryRow(conn)
   Query(conn)

   defer conn.Close()
}

func QueryRow(Db *sql.DB) {
   id := 1
   //Single line data query
   row := Db.QueryRow("select id,name,age from user where id=?",id)
   var user User
   err := row.Scan(&user.Id,&user.Name,&user.Age)
   if err == sql.ErrNoRows {
      fmt.Printf("not found data by id:%v\n",id)
   }

   if err != nil {
      fmt.Printf("scan faild,err: %v\n",err)
      return
   }
   fmt.Printf("user:%#v\n",user)
}

func Query(Db *sql.DB)  {
   id := 0
   //Multi row data query
   rows,err := Db.Query("select id,name,age from user where id>?",id)
   //Be sure to close the result set
   defer func() {
      if rows != nil {
         rows.Close()
      }
   }()
   //Query exception capture
   if err == sql.ErrNoRows {
      fmt.Printf("not found data by id:%v\n",id)
   }

   if err != nil {
      fmt.Printf("scan faild,err: %v\n",err)
      return
   }

   //Traverse all data
   for rows.Next() {
      var user User
      err := rows.Scan(&user.Id,&user.Name,&user.Age)
      if err == sql.ErrNoRows {
         fmt.Printf("not found data by id:%v\n",id)
      }

      if err != nil {
         fmt.Printf("scan faild,err: %v\n",err)
         return
      }
      fmt.Printf("user:%#v\n",user)
   }
}
func main() {
   connMysql()
}

Mysql insert update and delete

Use DB.Exec()

import (
   "fmt"
   _"github.com/go-sql-driver/mysql"
   "database/sql"
)

type User struct {
   Id   int64     `db:"id"`
   Name string    `db:"name"`
   Age  int       `db:"age"`
}

func Insert(DB *sql.DB) {
   username := "alex"
   age := 18
   result,err := DB.Exec("insert into user(name,age) values(?,?)",username,age)

   if err != nil {
      fmt.Printf("sql exec insert faild:err:%v\n",err)
      return
   }

   id,err := result.LastInsertId()
   if err != nil {
      fmt.Printf("last insert id faild,err:%v\n",err)
      return
   }

   affectRows,err := result.RowsAffected()
   if err != nil {
      fmt.Printf("Rows affects faild,err:%v\n",err)
      return
   }
   fmt.Printf("last insert id:%d, affect rows:%d\n",id,affectRows)
}

func Update(DB *sql.DB) {
   username := "bbq"
   age := 12
   result,err := DB.Exec("update user set name=?,age=? where id=?",username,age,3)

   if err != nil {
      fmt.Printf("sql exec update faild:err:%v\n",err)
      return
   }

   affectRows,err := result.RowsAffected()
   if err != nil {
      fmt.Printf("Rows affects faild,err:%v\n",err)
      return
   }
   fmt.Printf("affect rows:%d\n",affectRows)
}

func Delete(DB *sql.DB) {
   id := 5
   result,err := DB.Exec("delete from user where id=?",id)

   if err != nil {
      fmt.Printf("sql exec delete faild:err:%v\n",err)
      return
   }

   affectRows,err := result.RowsAffected()
   if err != nil {
      fmt.Printf("Rows affects faild,err:%v\n",err)
      return
   }
   fmt.Printf("affect rows:%d\n",affectRows)
}

func connMysql() {
   dns := "root:123456@tcp(localhost:3306)/test"
   conn,err := sql.Open("mysql",dns)
   if err != nil {
      fmt.Printf("connect mysql err:%v\n",err)
      return
   }

   err = conn.Ping()

   if err != nil {
      fmt.Printf("ping faild,err :%v\n",err)
   }

   fmt.Printf("connect mysql successfully!\n")
   //QueryRow(conn)
   //Query(conn)
   //Insert(conn)
   //Update(conn)
   Delete(conn)
   defer conn.Close()
}

mysql preprocessing

General sql processing flow
- The client splices the sql statements
- Client sends sql statement to mysql server
- The mysql server parses the sql statement and executes it, returning the output to the client
Pretreatment process
- Split sql into two parts, command part and data part
- First, send the command part to mysql server for sql preprocessing
- Then send the data part to mysql server for placeholder replacement
- mysql executes the sql statement and returns the result to the client
Advantages of pretreatment
- If the same sql is executed repeatedly, the performance will be very high
- Avoid sql injection problems

Pretreatment example

Query operation
- Db.Prepare(sql string)(*sql.Stmt,error)
- Stmt.Query()

func PrepareQuery(DB *sql.DB) {
   //Part 1: sending commands and placeholders
   stmt,err := DB.Prepare("select id,name,age from user where id>?")
   if err != nil {
      fmt.Printf("prepare faild,error:%v\n",err)
      return
   }
   //Part two: sending data and executing sql
   id := 1
   rows,err := stmt.Query(id)
   //Be sure to close the result set
   defer func() {
      if rows != nil {
         rows.Close()
      }
      if stmt != nil {
         stmt.Close()
      }
   }()
   //Query exception capture
   if err == sql.ErrNoRows {
      fmt.Printf("not found data by id:%v\n",id)
   }

   if err != nil {
      fmt.Printf("scan faild,err: %v\n",err)
      return
   }

   //Traverse all data
   for rows.Next() {
      var user User
      err := rows.Scan(&user.Id,&user.Name,&user.Age)
      if err == sql.ErrNoRows {
         fmt.Printf("not found data by id:%v\n",id)
      }

      if err != nil {
         fmt.Printf("scan faild,err: %v\n",err)
         return
      }
      fmt.Printf("user:%#v\n",user)
   }
}

Update operation (insert, update, delete)
- Db.Prepare(sql string)(*sql.Stmt,error)
- Stmt.Exec()

func PrepareInsert(DB *sql.DB) {
   //Part 1: sending commands and placeholders
   stmt,err := DB.Prepare("insert into user (name,age) values (?,?);")
   if err != nil {
      fmt.Printf("prepare faild,error:%v\n",err)
      return
   }
   //Part two: sending data and executing sql
   username := "zhangqiqi"
   age := 29
   result,err := stmt.Exec(username,age)

   if err != nil {
      fmt.Printf("sql exec insert faild:err:%v\n",err)
      return
   }

   id,err := result.LastInsertId()
   if err != nil {
      fmt.Printf("last insert id faild,err:%v\n",err)
      return
   }

   affectRows,err := result.RowsAffected()
   if err != nil {
      fmt.Printf("Rows affects faild,err:%v\n",err)
      return
   }
   fmt.Printf("last insert id:%d, affect rows:%d\n",id,affectRows)
}

mysql transaction instance

Ensure data consistency
Transaction operation of mysql
- DB.Begin() start transaction
- DB.Commit() commit transaction
- DB.Roback() rollback transaction

func Transaction(DB *sql.DB) {
   tx,err := DB.Begin()
   if err != nil {
      fmt.Printf("begin faild,err:%v\n",err)
      return
   }

   _,err = tx.Exec("insert into user (name,age)values (?,?)","jemmy",80)

   if err != nil {
      tx.Rollback()
      return
   }

   _,err = tx.Exec("update user set name=?,age=? where id=6","jemmxiny",60)

   if err != nil {
      tx.Rollback()
      return
   }

   err = tx.Commit()

   if err != nil {
      tx.Rollback()   //Rollback if data exception occurs
      return
   }
}

Introduction and use of sqlx Library

Features of sqlx:
- Easier to use
- Support for database, mysql,postgresql,oracle,sqlit
The use of sqlx
- Query: sqlx.DB.Get and sqlx.DB.Select
- Update, insert and delete: sqlx.DB.Exex()
- Transaction: sqlx.DB.Begin(),sqlx.DB.Commit(),sqlx.DB.Rollback

go get github.com/jmoiron/sqlx

Using examples

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

type User struct {
   Id   int64     `db:"id"`
   Name string    `db:"name"`
   Age  int       `db:"age"`
}

func connMysql() {
   dns := "root:123456@tcp(localhost:3306)/test"
   conn,err := sqlx.Connect("mysql",dns)
   if err != nil {
      fmt.Printf("connect mysql err:%v\n",err)
      return
   }
   //Timeout tests
   err = conn.Ping()

   if err != nil {
      fmt.Printf("ping faild,err :%v\n",err)
   }
   fmt.Printf("connect mysql successfully!\n")
   //Close connection
   //QueryRow(conn)
   //Query(conn)
   Insert(conn)
   defer conn.Close()

}

func QueryRow(Db *sqlx.DB) {
   id := 100
   //Single line data query
   var user User
   err := Db.Get(&user,"select id,name,age from user where id=?",id)
   //Blank data
   if err == sql.ErrNoRows {
      fmt.Printf("no record to found\n")
      return
   }
   if err != nil {
      fmt.Printf("get faild,err:%v\n",err)
      return
   }
   fmt.Printf("user:%#v\n",user)
}

func Query(Db *sqlx.DB)  {
   var user []*User
   id := 1
   //Multi row data query
   err := Db.Select(&user,"select id, name, age from user where id>?",id)
   if err == sql.ErrNoRows {
      fmt.Printf("no record found\n")
      return
   }

   if err != nil {
      fmt.Printf("select rows faild,err:%v\n",err)
      return
   }
   //Output query results
   fmt.Printf("user:%#v\n",user)
   for _,v := range user {
      fmt.Printf("%v\n",v)
   }
}

func Insert(Db *sqlx.DB) {
   username := "alex"
   age := 18
   result,err := Db.Exec("insert into user(name,age) values(?,?)",username,age)

   if err != nil {
      fmt.Printf("sql exec insert faild:err:%v\n",err)
      return
   }

   id,err := result.LastInsertId()
   if err != nil {
      fmt.Printf("last insert id faild,err:%v\n",err)
      return
   }

   affectRows,err := result.RowsAffected()
   if err != nil {
      fmt.Printf("Rows affects faild,err:%v\n",err)
      return
   }
   fmt.Printf("last insert id:%d, affect rows:%d\n",id,affectRows)
}

func main() {
   connMysql()
}

Redis development

Using a third-party library: github.com/garyburd/rediso/redis

Use of redis

func initRedis() (conn redis.Conn,err error) {
    conn,err = redis.Dial("tcp","127.0.0.1:6379")
   if err != nil {
      fmt.Printf("conn redis error:%v\n",err)
      return
   }
   fmt.Printf("conn redis succ\n")
   return
}

func testSetGet(conn redis.Conn)  {
   key := "abc"
   _,err := conn.Do("set",key,"this is a test!")
   if err != nil {
      fmt.Printf("set value faild,eror:%v\n",err)
      return
   }

   data,err := redis.String(conn.Do("get",key))
   if err != nil {
      fmt.Printf("get faild,err:%v\n",err)
      return
   }

   fmt.Printf("key:%s, value:%v\n",key,data)
}

func main() {
   conn,err := initRedis()
   if err != nil {
      return
   }
   testSetGet(conn)
}

Hash table operation

func testSetGet(conn redis.Conn)  {
   key := "abc"
   _,err := conn.Do("hset","books",key,"this is a test!")
   if err != nil {
      fmt.Printf("set value faild,eror:%v\n",err)
      return
   }

   data,err := redis.String(conn.Do("hget","books",key))
   if err != nil {
      fmt.Printf("get faild,err:%v\n",err)
      return
   }

   fmt.Printf("key:%s, value:%v\n",key,data)
}

Redis concurrent operation

func testMSetGet(conn redis.Conn) {
   key := "abc"
   key1 := "def"
   _,err := conn.Do("mset",key,key1)
   if err != nil {
      fmt.Printf("set value faild,eror:%v\n",err)
      return
   }

   //Data returned by multi value operation is received with strings
   data,err := redis.Strings(conn.Do("mget",key,key1))
   if err != nil {
      fmt.Printf("get faild,err:%v\n",err)
      return
   }

   //Cycle value
   for _,val := range data {
      fmt.Printf("key:%s, value:%v\n",key,val)
   }
}

Setup queue

Publish subscribe

func testQuenu(conn redis.Conn) {
   _,err := conn.Do("lpush","book_list","this is a test!","daadada")
   if err != nil {
      fmt.Printf("lpush value faild,eror:%v\n",err)
      return
   }

   data,err := redis.String(conn.Do("rpop","book_list"))
   if err != nil {
      fmt.Printf("get faild,err:%v\n",err)
      return
   }

   fmt.Printf("value:%s\n",data)
}

Connection pool

func newPool(serverAddr string,passwd string) (pool *redis.Pool) {
   return &redis.Pool{
      MaxIdle:         16,
      MaxActive:       1024,
      IdleTimeout:     240,
      Dial: func() (redis.Conn,error) {
         conn,err := redis.Dial("tcp",serverAddr)
         if err != nil {
            return nil,err
         }
         if len(passwd) > 0 {
            _,err := conn.Do("auth",passwd)
            if err != nil {
               return nil,err
            }
         }
         return conn,err
      },
      TestOnBorrow: func(c redis.Conn,t time.Time) error {
         if time.Since(t) < time.Minute {
            return nil
         }
         _,err := c.Do("ping")
         return err
      },
   }
}

func testRedisPool() {
   pool := newPool("127.0.0.1:6379","")
   conn := pool.Get()
   conn.Do("set","abcd","23134534665437372132")
   val,err := redis.String(conn.Do("get","abcd"))
   if err != nil {
      fmt.Printf("get faild,err:%v\n",err)
   }
   fmt.Printf("val:%v,err:%v\n",val,err)
   //Return connection to connection pool
   conn.Close()
}

Topics: Go SQL MySQL Redis github

Programmer Think

Getting started with Go Mysql and Redis

Mysql and Redis operations

Mysql development

SQL query

Mysql insert update and delete

mysql preprocessing

Pretreatment example

mysql transaction instance

Introduction and use of sqlx Library

Using examples

Redis development

Use of redis

Hash table operation

Redis concurrent operation

Setup queue

Connection pool

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