Go实战--go语言操作sqlite数据库(The way to go)

生命不止，继续 go go go !!!

继续与大家分享，go语言的实战，今天介绍的是如何操作sqlite数据库。

何为sqlite3？
SQLite is a self-contained, high-reliability, embedded, full-featured, public-domain, SQL database engine.

最主要的是，sqlite是一款轻型的数据库

官网：
https://www.sqlite.org/

database/sql包
go中有一个database/sql package，我们看看是怎样描述的：
Package sql provides a generic interface around SQL (or SQL-like) databases.

The sql package must be used in conjunction with a database driver

很清晰吧，需要我们自己提供一个database driver。当然，我们可以在github上找到相关的sqlite3的driver，稍后介绍。

下面介绍接个数据相关的操作：

Open

func Open(driverName, dataSourceName string) (*DB, error)

需要提供两个参数，一个driverName，一个数据库的名。

Prepare

func (db *DB) Prepare(query string) (*Stmt, error)

Prepare creates a prepared statement for later queries or executions.
返回的 *Stmt是什么鬼？

Stmt
Stmt is a prepared statement. A Stmt is safe for concurrent use by multiple goroutines.

func (*Stmt) Exec
准备完成后，就要执行了。

func (s *Stmt) Exec(args ...interface{}) (Result, error)

Exec executes a prepared statement with the given arguments and returns a Result summarizing the effect of the statement.
返回的Resault是什么鬼？

Result

type Result interface {        // LastInsertId returns the integer generated by the database        // in response to a command. Typically this will be from an        // "auto increment" column when inserting a new row. Not all        // databases support this feature, and the syntax of such        // statements varies.        LastInsertId() (int64, error)        // RowsAffected returns the number of rows affected by an        // update, insert, or delete. Not every database or database        // driver may support this.        RowsAffected() (int64, error)}

Query

func (s *Stmt) Query(args ...interface{}) (*Rows, error)

查询，返回的Rows是什么鬼？

Rows
Rows is the result of a query. Its cursor starts before the first row of the result set.

func (rs *Rows) Next() bool

Next prepares the next result row for reading with the Scan method

func (rs *Rows) Scan(dest ...interface{}) error

Scan copies the columns in the current row into the values pointed at by dest.

介绍少不多了，下面介绍一个sqlite3的Driver：

mattn/go-sqlite3
sqlite3 driver for go that using database/sql
github地址：
https://github.com/mattn/go-sqlite3

执行：

go get -u github.com/mattn/go-sqlite3

下面要开始我们的实战了！！！！

创建数据库，创建表

    //打开数据库，如果不存在，则创建    db, err := sql.Open("sqlite3", "./test.db")    checkErr(err)    //创建表    sql_table := `    CREATE TABLE IF NOT EXISTS userinfo(        uid INTEGER PRIMARY KEY AUTOINCREMENT,        username VARCHAR(64) NULL,        departname VARCHAR(64) NULL,        created DATE NULL    );    `    db.Exec(sql_table)

新建一个数据库叫test.db，并在这个数据库中建一个表，叫做userinfo。
userinfo中包含了四个字段，uid username departname created.
把uid设置为主键，并AUTOINCREMENT，自增。

插入数据

    stmt, err := db.Prepare("INSERT INTO userinfo(username, departname, created) values(?,?,?)")    checkErr(err)    res, err := stmt.Exec("wangshubo", "国务院", "2017-04-21")    checkErr(err)

显示Prepare，然后Exec.

接下来，就不再赘述了，我们需要一个基本的sql知识。

补充：import中_的作用
官方解释：

To import a package solely for its side-effects (initialization), use the blank identifier as explicit package name:import _ "lib/math"

当导入一个包时，该包下的文件里所有init()函数都会被执行。
然而，有些时候我们并不需要把整个包都导入进来，仅仅是是希望它执行init()函数而已。这个时候就可以使用 import _ 引用该包。

最后献上全部代码：

package mainimport (    "database/sql"    "fmt"    "time"    _ "github.com/mattn/go-sqlite3")func main() {    //打开数据库，如果不存在，则创建    db, err := sql.Open("sqlite3", "./foo.db")    checkErr(err)    //创建表    sql_table := `    CREATE TABLE IF NOT EXISTS userinfo(        uid INTEGER PRIMARY KEY AUTOINCREMENT,        username VARCHAR(64) NULL,        departname VARCHAR(64) NULL,        created DATE NULL    );    `    db.Exec(sql_table)    // insert    stmt, err := db.Prepare("INSERT INTO userinfo(username, departname, created) values(?,?,?)")    checkErr(err)    res, err := stmt.Exec("wangshubo", "国务院", "2017-04-21")    checkErr(err)    id, err := res.LastInsertId()    checkErr(err)    fmt.Println(id)    // update    stmt, err = db.Prepare("update userinfo set username=? where uid=?")    checkErr(err)    res, err = stmt.Exec("wangshubo_new", id)    checkErr(err)    affect, err := res.RowsAffected()    checkErr(err)    fmt.Println(affect)    // query    rows, err := db.Query("SELECT * FROM userinfo")    checkErr(err)    var uid int    var username string    var department string    var created time.Time    for rows.Next() {        err = rows.Scan(&uid, &username, &department, &created)        checkErr(err)        fmt.Println(uid)        fmt.Println(username)        fmt.Println(department)        fmt.Println(created)    }    rows.Close()    // delete    stmt, err = db.Prepare("delete from userinfo where uid=?")    checkErr(err)    res, err = stmt.Exec(id)    checkErr(err)    affect, err = res.RowsAffected()    checkErr(err)    fmt.Println(affect)    db.Close()}func checkErr(err error) {    if err != nil {        panic(err)    }}