mysql_example

package main

import (
    "database/sql"
    "fmt"

    _ "github.com/go-sql-driver/mysql"
)

var DB *sql.DB

func initDb() error {
    var err error
    dsn := "root:root@tcp(localhost:3306)/golang_db"
    DB, err = sql.Open("mysql", dsn)
    if err != nil {
        return err
    }

    DB.SetMaxOpenConns(100)
    DB.SetMaxIdleConns(16)
    return nil
}

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

func testQueryMultilRow() {
    sqlstr := "select id, name, age from user where id > ?"
    rows, err := DB.Query(sqlstr, 0)
    //重点关注， rows对象一定要close掉
    defer func() {
        if rows != nil {
            rows.Close()
        }
    }()

    if err != nil {
        fmt.Printf("query failed, err:%v
", err)
        return
    }

    for rows.Next() {
        var user User
        err := rows.Scan(&user.Id, &user.Name, &user.Age)
        if err != nil {
            fmt.Printf("scan failed, err:%v
", err)
            return
        }
        fmt.Printf("user:%#v
", user)
    }

}

func testQueryData() {
    for i := 0; i < 101; i++ {
        fmt.Printf("query %d times
", i)
        sqlstr := "select id, name, age from user where id=?"
        row := DB.QueryRow(sqlstr, 2)
        /*if row != nil {
            continue
        }*/
        var user User
        err := row.Scan(&user.Id, &user.Name, &user.Age)
        if err != nil {
            fmt.Printf("scan failed, err:%v
", err)
            return
        }

        fmt.Printf("id:%d name:%v age:%d
", user.Id, user.Name, user.Age)
    }

}

func testInsertData() {
    sqlstr := "insert into user(name, age) values(?, ?)"
    result, err := DB.Exec(sqlstr, "tom", 18)
    if err != nil {
        fmt.Printf("insert failed, err:%v
", err)
        return
    }

    id, err := result.LastInsertId()
    if err != nil {
        fmt.Printf("get last insert id failed, err:%v
", err)
        return
    }
    fmt.Printf("id is %d
", id)
}

func testUpdateData() {
    sqlstr := "update user set name=? where id=?"
    result, err := DB.Exec(sqlstr, "jim", 3)
    if err != nil {
        fmt.Printf("insert failed, err:%v
", err)
        return
    }

    affected, err := result.RowsAffected()
    if err != nil {
        fmt.Printf("get affected rows failed, err:%v
", err)
    }
    fmt.Printf("update db succ, affected rows:%d
", affected)
}

func testDeleteData() {
    sqlstr := "delete from user where id=?"
    result, err := DB.Exec(sqlstr, 3)
    if err != nil {
        fmt.Printf("insert failed, err:%v
", err)
        return
    }

    affected, err := result.RowsAffected()
    if err != nil {
        fmt.Printf("get affected rows failed, err:%v
", err)
    }
    fmt.Printf("delete db succ, affected rows:%d
", affected)
}

func testPrepareData() {
    sqlstr := "select id, name, age from user where id > ?"
    stmt, err := DB.Prepare(sqlstr)
    if err != nil {
        fmt.Printf("prepare failed, err:%v
", err)
        return
    }

    defer func() {
        if stmt != nil {
            stmt.Close()
        }
    }()

    rows, err := stmt.Query(0)
    //重点关注， rows对象一定要close掉
    defer func() {
        if rows != nil {
            rows.Close()
        }
    }()

    if err != nil {
        fmt.Printf("query failed, err:%v
", err)
        return
    }

    for rows.Next() {
        var user User
        err := rows.Scan(&user.Id, &user.Name, &user.Age)
        if err != nil {
            fmt.Printf("scan failed, err:%v
", err)
            return
        }
        fmt.Printf("user:%#v
", user)
    }
}

func testPrepareInsertData() {
    sqlstr := "insert into user(name, age) values(?, ?)"
    stmt, err := DB.Prepare(sqlstr)
    if err != nil {
        fmt.Printf("insert failed, err:%v
", err)
        return
    }

    defer func() {
        if stmt != nil {
            stmt.Close()
        }
    }()
    result, err := stmt.Exec("jim", 100)
    id, err := result.LastInsertId()
    if err != nil {
        fmt.Printf("get last insert id failed, err:%v
", err)
        return
    }
    fmt.Printf("id is %d
", id)
}

func testTrans() {

    conn, err := DB.Begin()
    if err != nil {
        if conn != nil {
            conn.Rollback()
        }
        fmt.Printf("begin failed, err:%v
", err)
        return
    }

    sqlstr := "update user set age = 1 where id = ?"
    _, err = conn.Exec(sqlstr, 1)
    if err != nil {
        conn.Rollback()
        fmt.Printf("exec sql:%s failed, err:%v
", sqlstr, err)
        return
    }

    sqlstr = "update user set age = 2 where id = ?"
    _, err = conn.Exec(sqlstr, 2)
    if err != nil {
        conn.Rollback()
        fmt.Printf("exec second sql:%s failed, err:%v
", sqlstr, err)
        return
    }
    err = conn.Commit()
    if err != nil {
        fmt.Printf("commit failed, err:%v
", err)
        conn.Rollback()
        return
    }
}

func main() {
    err := initDb()
    if err != nil {
        fmt.Printf("init db failed, err:%v
", err)
        return
    }

    //testQueryData()
    //testQueryMultilRow()
    //testInsertData()
    //testUpdateData()
    //testDeleteData()
    //testPrepareData()
    //testPrepareInsertData()
    testTrans()
}

package main

import (
    "database/sql"
    "fmt"

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

var DB *sqlx.DB

func initDb() error {
    var err error
    dsn := "root:root@tcp(localhost:3306)/golang_db"
    DB, err = sqlx.Open("mysql", dsn)
    if err != nil {
        return err
    }

    DB.SetMaxOpenConns(100)
    DB.SetMaxIdleConns(16)
    return nil
}

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

func testQuery() {
    sqlstr := "select id, name, age from user where id=?"
    var user User

    err := DB.Get(&user, sqlstr, 2)
    if err != nil {
        fmt.Printf("get failed, err:%v
", err)
        return
    }

    fmt.Printf("user:%#v
", user)
}

func testQueryMulti() {
    sqlstr := "select id, name, age from user where id>?"
    var user []User

    err := DB.Select(&user, sqlstr, 1)
    if err != nil {
        fmt.Printf("get failed, err:%v
", err)
        return
    }

    fmt.Printf("user:%#v
", user)
}

func testUpdate() {
    sqlstr := "update user set name=? where id=?"
    result, err := DB.Exec(sqlstr, "abc", 1)
    if err != nil {
        fmt.Printf("update failed, err:%v
", err)
        return
    }
    count, err := result.RowsAffected()
    if err != nil {
        fmt.Printf("affected rows failed, err:%v
", err)
        return
    }
    fmt.Printf("affect rows:%d
", count)
}

func queryDB(name string) {
    sqlstr := fmt.Sprintf("select id, name, age from user where name='%s'", name)
    fmt.Printf("sql:%s
", sqlstr)
    var user []User
    err := DB.Select(&user, sqlstr)
    if err != nil {
        fmt.Printf("select failed, err:%v
", err)
        return
    }

    for _, v := range user {
        fmt.Printf("user:%#v
", v)
    }
}

func queryDBBySqlx(name string) {
    sqlstr := "select id, name, age from user where name=?"
    //fmt.Printf("sql:%s
", sqlstr)
    var user []User
    err := DB.Select(&user, sqlstr, name)
    if err != nil {
        fmt.Printf("select failed, err:%v
", err)
        return
    }

    for _, v := range user {
        fmt.Printf("user:%#v
", v)
    }
}

func testSqlInject() {
    //queryDB("abc' or 1 = 1 #")
    //queryDB("name=abc' and (select count(*) from user ) < 10#")
    //queryDB("name=123' union select *from user #")
    queryDBBySqlx("name=123' union select *from user #")
}

func main() {

    err := initDb()
    if err != nil {
        fmt.Printf("init db failed, err:%v
", err)
        return
    }

    //testQuery()
    //testQueryMulti()
    //testUpdate()
    testSqlInject()
}