85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
package main
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import (
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"database/sql"
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"fmt"
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_ "github.com/go-sql-driver/mysql" //自动执行init()
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"log"
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)
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var db *sql.DB //是一个数据库连接池对象
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func initDb() (err error) {
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//数据库信息
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dsn := "root:123456@tcp(43.143.245.135:3306)/wangaodev"
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//连接数据库
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db, err = sql.Open("mysql", dsn) //不会校验用户名和密码是否正确
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if err != nil {
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//dsn 格式不正确会报错
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return err
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}
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//校验用户名和密码是否正确
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//尝试连接数据库
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err = db.Ping()
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if err != nil {
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return err
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}
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log.Printf("connect %s success.\n", dsn)
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//设置最大连接数
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db.SetMaxOpenConns(10)
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//设置最大空闲连接数
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db.SetMaxIdleConns(5)
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return nil
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}
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// 表结构对象
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type user struct {
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id int
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name string
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level string
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status int
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}
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// 查询单行数据
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func queryRow(id int) {
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var u user
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//查询单行记录的sql语句
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sqlstr := "select id,name,level,status from user where id=?"
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//执行并且拿到结果
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db.QueryRow(sqlstr, id).Scan(&u.id, &u.name, &u.level, &u.status) //从链接池中拿一个连接出来去数据库查询单条记录,scan方法自动释放连接，也就是必须调用scan方法
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fmt.Printf("user:%#v\n", u)
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}
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// 查询多行数据
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func queryMultiRow(level string) error {
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sqlstr := "select id,name,level,status from user where level=?"
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rows, err := db.Query(sqlstr, level)
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if err != nil {
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log.Printf("query multiRow err %v\n", err)
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return err
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}
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//非常重要.关闭rows持有的数据库连接
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defer rows.Close()
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for rows.Next() {
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var u user
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err = rows.Scan(&u.id, &u.name, &u.level, &u.status)
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if err != nil {
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log.Printf("scan err %v\n", err)
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return err
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}
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fmt.Printf("user:%#v\n", u)
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}
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return nil
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}
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// go链接mysql示例
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func main() {
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err := initDb()
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if err != nil {
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log.Fatalf("init DB failed:%v", err)
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}
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log.Println("init DB success.")
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queryRow(2)
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queryMultiRow("L1")
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}
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