iOS 開發之數據庫(SQLite)
編輯：IOS開發綜合
1.嵌入式數據庫
2.支持事件,不需要配置,不需要安裝,不需要管理員
3.支持大部分SQL92標准
4.完整的數據庫保存在磁盤上面一個文件,同一個數據庫文件可以在不同機器上面使用,最大支持數據庫到2T
5.整個系統少於3萬行,少於250KB的內存占用
開始使用SQLite：
1.引入頭文件
2.打開數據庫
3.執行SQL命令
4.關閉數據庫
以下代碼展示整個數據庫的 打開、關閉、增加、刪除、查找、修改。
創建一個單例:
#import@class Student; @interface DataBaseHandle : NSObject //創建一個單例 +(DataBaseHandle *)shareDB; //獲取Documents路徑 - (NSString *)documentsPath; //打開數據庫 - (void)openDB; //關閉數據庫 - (void)closeDB; //創建表 - (void)createTable; //插入信息 - (void)insertStudent:(Student *)stu; //修改信息 - (void)updateMessage; //刪除信息 - (void)deleteMessage; //查找全部 - (void)selectAllStudent; //條件查找(示例) - (void)selectWithSex:(NSString *)sex; @end
#import DataBaseHandle.h #import#import Student.h //全局單利對象 static DataBaseHandle *shareModle = nil; @implementation DataBaseHandle #pragma mark 實現單利 + (DataBaseHandle *)shareDB { if (nil == shareModle) { shareModle = [[DataBaseHandle alloc] init]; } return shareModle; } #pragma mark 獲取Documents路徑 - (NSString *)documentsPath { NSString *documentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0]; return documentPath; } //在操作數據之前引入框架(sql...3.0) //聲明一個數據庫的對象 static sqlite3 *db = nil; #pragma mark 打開數據庫 - (void)openDB { //判斷數據庫是不是為空 if (nil == db) { //與documents路徑拼接數據庫存放路徑(獲得存放路徑) NSString *dbPath = [[self documentsPath] stringByAppendingString:@/Student.sqlite]; //根據路徑打開數據庫,如該路徑下沒有數據庫,就自動創建一個數據庫 //打開數據庫(c語言中的語法) int result = sqlite3_open(dbPath.UTF8String, &db); //判斷是否打開數據庫成功 if (result == SQLITE_OK) { NSLog(@數據庫打開成功); } else { NSLog(@數據庫打開失敗); } } } #pragma mark 關閉數據庫 - (void)closeDB { int result = sqlite3_close(db); if (result == SQLITE_OK) { //如果關閉成功,置為nill db = nil; NSLog(@數據庫關閉成功); } else { NSLog(@數據庫關閉失敗); } } #pragma mark 創建表 - (void)createTable { //要創建表,就要使用SQL語句. //SQL語句在這是以字符串的形式存在的 NSString *createString = @CREATE TABLE IF NOT EXISTS student (sid INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL , sname TEXT, ssex TEXT, sage TEXT); //執行SQL語句 int result = sqlite3_exec(db, createString.UTF8String, NULL, NULL, NULL); if (result == SQLITE_OK) { NSLog(@創建表成功); } else { NSLog(@創建失敗); } } #pragma mark 插入信息 - (void)insertStudent:(Student *)stu { //准備插入語句 NSString *insertString = [NSString stringWithFormat:@INSERT INTO student (sname,ssex,sage) VALUES ('%@','%@','%@'),stu.name,stu.sex,stu.age]; //執行語句 int result = sqlite3_exec(db, insertString.UTF8String, NULL, NULL, NULL); if (result == SQLITE_OK) { NSLog(@插入成功); } else { NSLog(@插入失敗); } } #pragma mark 修改數據 - (void)updateMessage { //准備修改語句 NSString *undataString = @UPDATE student SET ssex = '女' ,sname = '小夢' WHERE sid = 10; int result = sqlite3_exec(db, undataString.UTF8String, NULL, NULL, NULL); if (result == SQLITE_OK) { NSLog(@修改成功); } else { NSLog(@修改失敗); } } #pragma mark 刪除數據 - (void)deleteMessage { //准備刪除語句 NSString *deleteString = @DELETE FROM student WHERE sid = 1; int result = sqlite3_exec(db, deleteString.UTF8String, NULL, NULL, NULL); if (result == SQLITE_OK) { NSLog(@delete OK); } else { NSLog(@delete _NO); } } #pragma mark 查找全部 - (void)selectAllStudent { //准備查找語句 NSString *selectAll = @SELECT *FROM student; //創建伴隨指針 sqlite3_stmt *stmt = nil; //預備執行 int result = sqlite3_prepare(db, selectAll.UTF8String, -1, &stmt, NULL); if (result == SQLITE_OK) { //在沒有查找完成之前一直循環執行 while (sqlite3_step(stmt) == SQLITE_ROW) { //取出sid(第0列) NSInteger sid = sqlite3_column_int(stmt, 0); //取出sname(第1列) NSString *sname = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 1)]; //取出ssex(第2列) NSString *ssex = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 2)]; //取出sage(第3列) NSString *sage = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 3)]; NSLog(@sid:%d sname:%@ ssex:%@ sage:%@,sid,sname,ssex,sage); } sqlite3_finalize(stmt); } else { //如果查找失敗,結束伴隨指針 sqlite3_finalize(stmt); NSLog(@查找失敗); } } #pragma mark 條件查找 - (void)selectWithSex:(NSString *)sex { //准備查找語句 NSString *selecstString = @SELECT * FROM student WHERE ssex = ?; //創建伴隨指針 sqlite3_stmt *stmt = nil; //預執行 int result = sqlite3_prepare(db, selecstString.UTF8String, -1, &stmt, NULL); if (result == SQLITE_OK) { //綁定?的值 //1代表第一個問號?和哪個參數綁定 sqlite3_bind_text(stmt, 1, sex.UTF8String, -1, NULL); while (sqlite3_step(stmt) == SQLITE_ROW) { NSInteger sid = sqlite3_column_int(stmt, 0); NSString *sname = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 1)]; NSString *ssex = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 2)]; NSString *sage = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 3)]; NSLog(@sid: %d sname: %@ ssex: %@ sage: %@,sid,sname,ssex,sage); } } else { //關閉指針 sqlite3_finalize(stmt); NSLog(@查詢失敗); } } @end
創建一個Student類
#import在 ViewController.m中 ViewDidLoad 調用方法@interface Student : NSObject @property(nonatomic,strong)NSString *name; @property(nonatomic,strong)NSString *age; @property(nonatomic,strong)NSString *sex; @end
//打印路徑
NSLog(@%@,[[DataBaseHandle shareDB] documentsPath]);
//打開數據庫
[[DataBaseHandle shareDB] openDB];
//創建表
[[DataBaseHandle shareDB] createTable];
//插入信息
// Student *stu = [[Student alloc] init];
// stu.name = @小露;
// stu.age = @29;
// stu.sex = @女;
// [[DataBaseHandle shareDB] insertStudent:stu];
//修改
// [[DataBaseHandle shareDB] updateMessage];
//刪除
// [[DataBaseHandle shareDB] deleteMessage];
//查找全部信息
// [[DataBaseHandle shareDB] selectAllStudent];
//根據條件查找信息
[[DataBaseHandle shareDB] selectWithSex:@女];
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