IOS中SQLite3的使用

介绍

sqlite是纯C语言中底层的数据库，在OC和Swift中都是经常使用的数据库，在开发中，可以使用代码创建数据库，可以使用图形化界面创建数据库。例如SQLiteManager、SQLiteStudio等

常用方法

方法名称	描述
OpaquePointer: *db	数据库句柄，跟文件句柄FIFL类似，这里是sqlite3指针
sqlite3_stmt: *stmt	相当于ODBC的Command对象，用于保存编译好的SQL语句
sqlite3_open()	打开数据库，没有数据库时创建
sqlite3_exec()	执行非查询的SQL语句
sqlite3_step()	在调用sqlite3_prepare后，使用这个函数在记录集中移动
sqlite3_close()	关闭数据库文件
sqlite3_column_text()	取text类型的数据
sqlite3_column_blob()	取blob类型的数据
sqlite3_column_int()	取int类型的数据

引入Sqlite

引入Sqlite数据库的方式，网上有很多，我这里就不在赘述了

具体操作

数据库连接操作(包括数据库的创建，表的创建，表的查询，修改，删除等操作)

class SQLiteConnect {

    var db :OpaquePointer? = nil
    let sqlitePath :String

    init?(path :String) {
        sqlitePath = path
        db = self.openDatabase(sqlitePath)

        if db == nil {
            return nil
        }
    }

    // 連結資料庫 connect database
    func openDatabase(_ path :String) -> OpaquePointer? {
        var connectdb: OpaquePointer? = nil
        if sqlite3_open(path, &connectdb) == SQLITE_OK {
            print("Successfully opened database \(path)")
            return connectdb!
        } else {
            print("Unable to open database.")
            return nil
        }
    }

    // 建立資料表 create table
    func createTable(_ tableName :String, columnsInfo :[String]) -> Bool {
        let sql = "create table if not exists \(tableName) "
            + "(\(columnsInfo.joined(separator: ",")))"

        if sqlite3_exec(self.db, sql.cString(using: String.Encoding.utf8), nil, nil, nil) == SQLITE_OK{
            return true
        }

        return false
    }

    // 新增資料
    func insert(_ tableName :String, rowInfo :[String:String]) -> Bool {
        var statement :OpaquePointer? = nil
        let sql = "insert into \(tableName) "
            + "(\(rowInfo.keys.joined(separator: ","))) "
            + "values (\(rowInfo.values.joined(separator: ",")))"

        if sqlite3_prepare_v2(self.db, sql.cString(using: String.Encoding.utf8), -1, &statement, nil) == SQLITE_OK {
            if sqlite3_step(statement) == SQLITE_DONE {
                return true
            }
            sqlite3_finalize(statement)
        }

        return false
    }

    // 讀取資料
    func fetch(_ tableName :String, cond :String?, order :String?) -> OpaquePointer {
        var statement :OpaquePointer? = nil
        var sql = "select * from \(tableName)"
        if let condition = cond {
            sql += " where \(condition)"
        }

        if let orderBy = order {
            sql += " order by \(orderBy)"
        }

        sqlite3_prepare_v2(self.db, sql.cString(using: String.Encoding.utf8), -1, &statement, nil)

        return statement!
    }

    // 更新資料
    func update(_ tableName :String, cond :String?, rowInfo :[String:String]) -> Bool {
        var statement :OpaquePointer? = nil
        var sql = "update \(tableName) set "

        // row info
        var info :[String] = []
        for (k, v) in rowInfo {
            info.append("\(k) = \(v)")
        }
        sql += info.joined(separator: ",")

        // condition
        if let condition = cond {
            sql += " where \(condition)"
        }

        if sqlite3_prepare_v2(self.db, sql.cString(using: String.Encoding.utf8), -1, &statement, nil) == SQLITE_OK {
            if sqlite3_step(statement) == SQLITE_DONE {
                return true
            }
            sqlite3_finalize(statement)
        }

        return false

    }

    // 刪除資料
    func delete(_ tableName :String, cond :String?) -> Bool {
        var statement :OpaquePointer? = nil
        var sql = "delete from \(tableName)"

        // condition
        if let condition = cond {
            sql += " where \(condition)"
        }

        if sqlite3_prepare_v2(self.db, sql.cString(using: String.Encoding.utf8), -1, &statement, nil) == SQLITE_OK {
            if sqlite3_step(statement) == SQLITE_DONE {
                return true
            }
            sqlite3_finalize(statement)
        }

        return false
    }

}

使用

var db :SQLiteConnect?

    override func viewDidLoad() {
        super.viewDidLoad()


        // 資料庫檔案的路徑
        let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        let sqlitePath = urls[urls.count-1].absoluteString + "sqlite3.db"

        // 印出儲存檔案的位置
        print(sqlitePath)

        // SQLite 資料庫
        db = SQLiteConnect(path: sqlitePath)

        if let mydb = db {

            // create table
            let _ = mydb.createTable("students", columnsInfo: [
                "id integer primary key autoincrement",
                "name text",
                "height double"])

            // insert
            let _ = mydb.insert("students", rowInfo: ["name":"'大強'","height":"178.2"])

            // select
            let statement = mydb.fetch("students", cond: "1 == 1", order: nil)
            while sqlite3_step(statement) == SQLITE_ROW{
                let id = sqlite3_column_int(statement, 0)
                let name = String(cString: sqlite3_column_text(statement, 1))
                let height = sqlite3_column_double(statement, 2)
                print("\(id). \(name) 身高： \(height)")
            }
            sqlite3_finalize(statement)

            // update
            let _ = mydb.update("students", cond: "id = 1", rowInfo: ["name":"'小強'","height":"176.8"])

            // delete
            let _ = mydb.delete("students", cond: "id = 5")

        }
    }

使用sqlite.swift框架

import UIKit
import SQLite

struct SQLiteManager {

   private var db: Connection!
   private let users = Table("users") //表名
   private let id = Expression<Int64>("id")      //主键
   private let name = Expression<String>("name")  //列表1
   private let email = Expression<String>("email") //列表2

    init() {
        createdsqlite3()
    }

    //创建数据库文件
    mutating func createdsqlite3(filePath: String = "/Documents")  {

        let sqlFilePath = NSHomeDirectory() + filePath + "/db.sqlite3"
        do {
            db = try Connection(sqlFilePath)
            try db.run(users.create { t in
                t.column(id, primaryKey: true)
                t.column(name)
                t.column(email, unique: true)
                })
        } catch { print(error) }
    }

    //插入数据
    func insertData(_name: String, _email: String){
        do {
            let insert = users.insert(name <- _name, email <- _email)
            try db.run(insert)
        } catch {
            print(error)
        }
    }

    //读取数据
    func readData() -> [(id: String, name: String, email: String)] {
    var userData = (id: "", name: "", email: "")
        var userDataArr = [userData]
        for user in try! db.prepare(users) {
            userData.id = String(user[id])
            userData.name = user[name]
            userData.email = user[email]
            userDataArr.append(userData)
        }
        return userDataArr
    }

    //更新数据
    func updateData(userId: Int64, old_name: String, new_name: String) {
        let currUser = users.filter(id == userId)
        do {
            try db.run(currUser.update(name <- name.replace(old_name, with: new_name)))
        } catch {
            print(error)
        }

    }

    //删除数据
    func delData(userId: Int64) {
        let currUser = users.filter(id == userId)
        do {
            try db.run(currUser.delete())
        } catch {
            print(error)
        }
    }
}

使用：

let sqliteContext = SQLiteManager() //如果没有,默认创建数据库及表格
    //插入数据
    sqliteContext.insertData("username", _email: "[email protected]")
    //读取全部数据
    //要想读取指定数据，可以自己自定义转换成其他模型，比如字典+元组，可以根据id查找
    let dataM = sqliteContext.readData()
    print(dataM) 
    //更新数据 1 -> 用户id
    sqliteContext.updateData(1, old_name: "oldValue", new_name: "newValue")
    //删除数据
    sqliteContext.delData(1) // 1 -> 用户id

参考资料

ios sqlite3的使用
Swift起步走
swift第三方框架之sqlite3
github的sqlite.swift