Go實戰--go語言操作sqlite資料庫(The way to go)

生命不止，繼續 go go go !!!

繼續與大家分享，go語言的實戰，今天介紹的是如何操作sqlite資料庫。

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

最主要的是，sqlite是一款輕型的資料庫

The sql packagemust be used in conjunction with a database driver

很清晰吧，需要我們自己提供一個database driver。當然，我們可以在github上找到相關的sqlite3的driver，稍後介紹。

下面介紹接個數據相關的操作：

Open

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

需要提供兩個引數，一個driverName，一個數據庫的名。

Prepare

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

Prepare creates a prepared statement for later queries or executions.

返回的 *Stmt是什麼鬼？

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

func (*Stmt) Exec準備完成後，就要執行了。

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是什麼鬼？

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)

查詢，返回的Rows是什麼鬼？

RowsRows 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.

介紹少不多了，下面介紹一個sqlite3的Driver：

執行：

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

下面要開始我們的實戰了！！！！

建立資料庫，建立表

//開啟資料庫，如果不存在，則建立
db, err := sql.Open("sqlite3", "./test.db")
checkErr(err)

//建立表
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)

新建一個數據庫叫test.db，並在這個資料庫中建一個表，叫做userinfo。

userinfo中包含了四個欄位，uid username departname created.

把uid設定為主鍵，並AUTOINCREMENT，自增。

插入資料

stmt, err := db.Prepare("INSERT INTO userinfo(username, departname, created) values(?,?,?)")
checkErr(err)

res, err := stmt.Exec("wangshubo", "國務院", "2017-04-21")
checkErr(err)

顯示Prepare，然後Exec.

接下來，就不再贅述了，我們需要一個基本的sql知識。

補充：import中_的作用官方解釋：

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

import _ "lib/math"

當匯入一個包時，該包下的檔案裡所有init()函式都會被執行。

然而，有些時候我們並不需要把整個包都匯入進來，僅僅是是希望它執行init()函式而已。這個時候就可以使用 import _ 引用該包。

最後獻上全部程式碼：

package main

import (
"database/sql"
"fmt"
"time"

_ "github.com/mattn/go-sqlite3"
)

func main() {
//開啟資料庫，如果不存在，則建立
db, err := sql.Open("sqlite3", "./foo.db")
checkErr(err)

//建立表
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", "國務院", "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)
}
}