如何在 iOS 应用程序中删除 SQLite 中的记录 [英] How to delete records in SQLite in iOS Application

问题描述

我正在尝试删除应用程序中的记录，但未能成功.

I am trying t delete records in my application, but I could not successfully able to do so.

这是代码片段.

if(trackingHistory != nil){
    for (NSString *trkNum in trackingHistory) {
        if(trkNum == NULL){
            continue;
        }
        if (sqlite3_open(dbpath, &database) == SQLITE_OK)
        {
            NSString *querySQL = [NSString stringWithFormat: @"delete from TRACK_IT where TRACKING_NUMBER=\"%@\"",trkNum];
            const char *query_stmt = [querySQL UTF8String];
            sqlite3_prepare_v2(database, query_stmt,-1, &statement, NULL);
            if (sqlite3_step(statement) == SQLITE_DONE)
            {
                NSLog(@"deleted record");
                //return YES;
            } else {
                NSLog(@"Failed to delete record");
                // return NO;
            }
            sqlite3_reset(statement);
        }
    }
}

请告诉我可能有什么问题?

Please let me know what could be wrong?

推荐答案

您的查询字符串似乎使用双引号而不是单引号:

Your query string appears to be using double quotes instead of single quotes:

NSString *querySQL = [NSString
    stringWithFormat: @"delete from TRACK_IT where TRACKING_NUMBER=\"%@\"",trkNum];
//                                                                  ^   ^
//                                                                  |   |
//                                                              Here and Here

用单引号替换应该可以解决这个语法错误:

Replacing with single quotes should fix this syntax error:

NSString *querySQL = [NSString
    stringWithFormat: @"delete from TRACK_IT where TRACKING_NUMBER='%@'",trkNum];

但是，除非 trkNum 内置在您自己的程序中，否则不要使用这种删除记录的方法:如果数据来自用户，您的应用程序就会受到 SQL 注入攻击.

However, unless trkNum is built into your own program, do not use this method of deleting records: if the data comes from the user, you open your app to SQL injection attacks.

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