关于go:go源码阅读databasesql

一、介绍
database/sql 采纳策略模式，每个driver实现驱动，提供一个注册连接词。

var (    driversMu sync.RWMutex    drivers   = make(map[string]driver.Driver))// Register makes a database driver available by the provided name.// If Register is called twice with the same name or if driver is nil,// it panics.func Register(name string, driver driver.Driver) {    driversMu.Lock()    defer driversMu.Unlock()    if driver == nil {        panic("sql: Register driver is nil")    }    if _, dup := drivers[name]; dup {        panic("sql: Register called twice for driver " + name)    }    drivers[name] = driver}

当咱们应用不同的数据库的时候，只有把应用的驱动注册进去就能够了。
比方在 github.com/go-sql-driver/mysql mysql驱动库里。
有一段代码
github.com/go-sql-driver/mysql/driver.go

func init() {    sql.Register("mysql", &MySQLDriver{})}

这里注册是在drivers的map的一个key，关联一个driver。