数据库Sqlite-(Xcode7,ios9,objective-C)

来源：互联网发布：自己的社会网络编辑：程序博客网时间：2024/05/17 02:23

首先，纪录一下学习的注意点：获取地址的方式和之前的版本其实没有变化，但是要注意一点

NSArray *dirPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    NSString *docsDir = [dirPath objectAtIndex:0];

    NSArray *dirPath = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);    NSString *docsDir = [dirPath objectAtIndex:0];

这两段代码只差了其中一个很相似的参数，一开始的时候一直没搞懂为什么路径从之前的/documents变成了/documentation，这是很大差异的，因为暂时没有从模拟器的沙箱中找到这样一个路径，所以刚开始的时候也许会没整理好导致错误。

另外基本的操作：（增、查）剩下的删、改其实没有其他区别了就是语句的问题了，注意bug主要会出现在sql语句的错误中，其他么就没什么注意点了。

- (IBAction)save:(id)sender {    sqlite3_stmt *statement;    const char *dbPath = [databasePath UTF8String];        if (sqlite3_open(dbPath, &database)==SQLITE_OK) {        if ([stuid.text isEqualToString:@""]) {            UIAlertView * av = [[UIAlertView alloc] initWithTitle:@"msg" message:@"Sorry! id nil" delegate:self cancelButtonTitle:@"NO" otherButtonTitles:nil, nil];            [av show];        }else        {            NSString * insertSQL = [NSString stringWithFormat:@"INSERT INTO INFO (num,classname,name) VALUES(\"%@\",\"%@\",\"%@\")",stuid.text,classname.text,name.text];            const char *insertStatement = [insertSQL UTF8String];            NSLog(@"%@",insertSQL);            sqlite3_prepare_v2(database, insertStatement, -1, &statement, NULL);            if (sqlite3_step(statement) == SQLITE_DONE) {                stuid.text=@"";                classname.text=@"";                name.text=@"";                UIAlertView * av = [[UIAlertView alloc] initWithTitle:@"msg" message:@"YES!Saved" delegate:self cancelButtonTitle:@"NO" otherButtonTitles:nil, nil];                [av show];            }            else            {                UIAlertView * av = [[UIAlertView alloc] initWithTitle:@"msg" message:@"Sorry!Saved failed" delegate:self cancelButtonTitle:@"NO" otherButtonTitles:nil, nil];                [av show];            }            sqlite3_finalize(statement);            sqlite3_close(database);        }    }else{NSLog(@"failed in Saving!");}}- (IBAction)query:(id)sender {    const char *dbpath = [databasePath UTF8String];    sqlite3_stmt *statement;    NSLog(@"query");    if(sqlite3_open(dbpath, &database)==SQLITE_OK){        NSString *querySQL = [NSString stringWithFormat:@"SELECT classname,name from info where num=\"%@\"",stuid.text];        const char *queryStatement = [querySQL UTF8String];        if (sqlite3_prepare_v2(database, queryStatement, -1, &statement, NULL)==SQLITE_OK) {            if (sqlite3_step(statement)==SQLITE_ROW) {                NSString *classnameField = [[NSString alloc] initWithUTF8String:(const char*)sqlite3_column_text(statement, 0)];                classname.text = classnameField;                NSString *nameField = [[NSString alloc] initWithUTF8String:(const char*)sqlite3_column_text(statement, 1)];                name.text = nameField;                                UIAlertController *controller = [UIAlertController alertControllerWithTitle:@"we" message:@"query good" preferredStyle:UIAlertControllerStyleAlert];                UIAlertAction *one =[UIAlertAction actionWithTitle:@"ok" style:UIAlertActionStyleDefault handler:nil];                [controller addAction:one];                [self presentViewController:controller animated:YES completion:nil];                                            }else{                                NSLog(@"NONONONONO");            }            sqlite3_finalize(statement);                    }else{NSLog(@"tag1");}            sqlite3_close(database);    }}- (IBAction)clear:(id)sender {    stuid.text = @"";    classname.text = @"";    name.text = @"";}

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