127 lines
4.1 KiB
Markdown
127 lines
4.1 KiB
Markdown
# 5.2 MySQL
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The LAMP stack has been very popular on the internet in recent years, and the M in LAMP stand for MySQL. MySQL is famous because it's open source and easy to use. As such, it became the defacto database in the back-ends of many websites.
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## MySQL drivers
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There are a couple of drivers that support MySQL in Go. Some of them implement the `database/sql` interface, and others use their own interface standards.
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- [https://github.com/go-sql-driver/mysql](https://github.com/go-sql-driver/mysql) supports `database/sql`, written in pure Go.
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- [https://github.com/ziutek/mymysql](https://github.com/ziutek/mymysql) supports `database/sql` and user defined interfaces, written in pure Go.
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- [https://github.com/Philio/GoMySQL](https://github.com/Philio/GoMySQL) only supports user defined interfaces, written in pure Go.
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I'll use the first driver in the following examples (I use this one in my personal projects too), and I also recommend that you use it for the following reasons:
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- It's a new database driver and supports more features.
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- Fully supports `database/sql` interface standards.
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- Supports keepalive, long connections with thread-safety.
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## Samples
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In the following sections, I'll use the same database table structure for different databases, then create SQL as follows:
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CREATE TABLE `userinfo` (
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`uid` INT(10) NOT NULL AUTO_INCREMENT,
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`username` VARCHAR(64) NULL DEFAULT NULL,
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`department` VARCHAR(64) NULL DEFAULT NULL,
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`created` DATE NULL DEFAULT NULL,
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PRIMARY KEY (`uid`)
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);
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The following example shows how to operate on a database based on the `database/sql` interface standards.
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package main
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import (
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_ "github.com/go-sql-driver/mysql"
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"database/sql"
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"fmt"
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)
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func main() {
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db, err := sql.Open("mysql", "astaxie:astaxie@/test?charset=utf8")
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checkErr(err)
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// insert
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stmt, err := db.Prepare("INSERT userinfo SET username=?,department=?,created=?")
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checkErr(err)
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res, err := stmt.Exec("astaxie", "研发部门", "2012-12-09")
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checkErr(err)
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id, err := res.LastInsertId()
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checkErr(err)
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fmt.Println(id)
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// update
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stmt, err = db.Prepare("update userinfo set username=? where uid=?")
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checkErr(err)
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res, err = stmt.Exec("astaxieupdate", id)
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checkErr(err)
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affect, err := res.RowsAffected()
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checkErr(err)
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fmt.Println(affect)
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// query
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rows, err := db.Query("SELECT * FROM userinfo")
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checkErr(err)
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for rows.Next() {
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var uid int
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var username string
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var department string
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var created string
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err = rows.Scan(&uid, &username, &department, &created)
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checkErr(err)
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fmt.Println(uid)
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fmt.Println(username)
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fmt.Println(department)
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fmt.Println(created)
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}
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// delete
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stmt, err = db.Prepare("delete from userinfo where uid=?")
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checkErr(err)
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res, err = stmt.Exec(id)
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checkErr(err)
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affect, err = res.RowsAffected()
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checkErr(err)
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fmt.Println(affect)
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db.Close()
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}
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func checkErr(err error) {
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if err != nil {
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panic(err)
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}
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}
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Let me explain a few of the important functions here:
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- `sql.Open()` opens a registered database driver. The Go-MySQL-Driver registered the mysql driver here. The second argument is the DSN (Data Source Name) that defines information pertaining to the database connection. It supports following formats:
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user@unix(/path/to/socket)/dbname?charset=utf8
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user:password@tcp(localhost:5555)/dbname?charset=utf8
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user:password@/dbname
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user:password@tcp([de:ad:be:ef::ca:fe]:80)/dbname
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- `db.Prepare()` returns a SQL operation that is going to be executed. It also returns the execution status after executing SQL.
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- `db.Query()` executes SQL and returns a Rows result.
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- `stmt.Exec()` executes SQL that has been prepared and stored in Stmt.
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Note that we use the format `=?` to pass arguments. This is necessary for preventing SQL injection attacks.
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## Links
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- [Directory](preface.md)
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- Previous section: [database/sql interface](05.1.md)
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- Next section: [SQLite](05.3.md)
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