Question

我有两个不同的数据库，Databse1和Database2，在这两个数据库中都包含相同的名称表＆＃34; tblSubUnit＆＃34;这个表有一个列名是＆＃34;收藏夹＆＃34;，现在我想用Database2表列（收藏夹）替换Database1表列。所以请帮我解决更新/更新问题。

我为此创建了一个函数来附加这两个数据库，但是在我无法更新/替换列后，请提前帮助我。

代码：

- (void)UpdateFavoriteData:(NSString*)query{

    NSString * language = [[NSLocale preferredLanguages] objectAtIndex:0];

    NSString *path = [[NSBundle mainBundle] pathForResource:language ofType:@"lproj"];

    if(path==nil){
        path = [[NSBundle mainBundle] pathForResource:@"Base" ofType:@"lproj"];
    }
    NSString *l_DatabasePathFromApp = [path stringByAppendingPathComponent:self.m_DatabaseName];

    sqlite3 *bookLoansDB;
    if (sqlite3_open([self.m_DatabasePath UTF8String], &bookLoansDB) == SQLITE_OK) {
        NSString *attachSQL = [NSString stringWithFormat: @"ATTACH DATABASE \'%s\' AS FavoriteData", [l_DatabasePathFromApp UTF8String]];
        char *errorMessage;
        if (sqlite3_exec(bookLoansDB, [attachSQL UTF8String], NULL, NULL, &errorMessage) == SQLITE_OK) {
            sqlite3_stmt *selectStmt;

            NSString *selectSQL = @"UPDATE [FavoriteData.SubUnit], [main.SubUnit] SET [FavoriteData.SubUnit].[Faverite] = [main.SubUnit].[Faverite]";
            if (sqlite3_prepare_v2(bookLoansDB, [selectSQL UTF8String] , -1, &selectStmt, nil) == SQLITE_OK) {
                if(sqlite3_step(selectStmt) == SQLITE_DONE) {
                }
            }
            else {
                NSLog(@"Error while Update statement: '%s'", sqlite3_errmsg(bookLoansDB));
            }
        }
        else {
            NSLog(@"Error while attaching databases: '%s'", errorMessage);
        }
    }
    else {
        sqlite3_close(bookLoansDB);
    }

}

我正在尝试这么多的更新查询，但每次都得到相同的结果＆＃34;更新语句错误＆＃34;所以请帮助我如何使用另一个数据库表列数据更新一个数据库表列。

Answer 1

我得到了解决方案，我终于得到了正确的查询。见下面的答案。

- (void)UpdateFavoriteData:(NSString*)query{

    NSString * language = [[NSLocale preferredLanguages] objectAtIndex:0];

    NSString *path = [[NSBundle mainBundle] pathForResource:language ofType:@"lproj"];

    if(path==nil){
        path = [[NSBundle mainBundle] pathForResource:@"Base" ofType:@"lproj"];
    }
    NSString *l_DatabasePathFromApp = [path stringByAppendingPathComponent:self.m_DatabaseName];


    sqlite3 *bookLoansDB;
    if (sqlite3_open([self.m_DatabasePath UTF8String], &bookLoansDB) == SQLITE_OK) {
        NSString *attachSQL = [NSString stringWithFormat: @"ATTACH DATABASE \'%s\' AS FFavorite", [l_DatabasePathFromApp UTF8String]];
        char *errorMessage;
        if (sqlite3_exec(bookLoansDB, [attachSQL UTF8String], NULL, NULL, &errorMessage) == SQLITE_OK) {
            sqlite3_stmt *selectStmt;

            NSString *selectSQL = @"update FFavorite.SubUnit set Faverite = (SELECT main.SubUnit.Faverite FROM main.SubUnit WHERE FFavorite.SubUnit.unit_id = main.SubUnit.unit_id)";
            if (sqlite3_prepare_v2(bookLoansDB, [selectSQL UTF8String] , -1, &selectStmt, nil) == SQLITE_OK) {
                if(sqlite3_step(selectStmt) == SQLITE_DONE) {
                }
            }
            else {
                NSLog(@"Error while creating select statement: '%s'", sqlite3_errmsg(bookLoansDB));
            }
        }
        else {
            NSLog(@"Error while attaching databases: '%s'", errorMessage);
        }
    }
    else {
        sqlite3_close(bookLoansDB);
    }

}

更新/替换两个不同的数据库表列

1 个答案: