Question

我有一个方法，它从数据库生成返回值的字典：

- (NSDictionary *)getParametersForPreset:(NSUInteger)presetID plants:(NSArray *)plants
{

NSString *loggers = @"";
NSString *invertors = @"";
NSString *plantsList = @"";

const char *sql = "SELECT loggerID, invertorID FROM records WHERE presetID IN (?) AND plantID IN (?)";  
BOOL isEmpty = YES;

sqlite3_stmt *statement;

if (sqlite3_prepare_v2(database, sql, -1, &statement, NULL) != SQLITE_OK)
{
    NSLog(@"Error: '%s'.", sqlite3_errmsg(database));
}

for (int i = 0; i < [plants count]; i++) {
    if (i == 0)
    {
        plantsList = [NSString stringWithFormat:@"'%@'",[[plants objectAtIndex:0] valueForKey:@"id"]];
    }
    else
    {
        plantsList = [plantsList stringByAppendingFormat:@",'%@'",[[plants objectAtIndex:i] valueForKey:@"id"]];
    }
}

NSLog(@"plants: %@", plantsList);
NSLog(@"preset: %d", presetID);

sqlite3_bind_int(statement, 1, presetID);
sqlite3_bind_text(statement, 2, [plantsList UTF8String], -1, SQLITE_TRANSIENT);

NSMutableDictionary *dictionary = [[[NSMutableDictionary alloc] init] autorelease];
int i = 0;

while (sqlite3_step(statement) == SQLITE_ROW)
{
    if (i == 0)
    {
        loggers = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 0)];
        invertors = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 1)];

        isEmpty = NO;
        i++;
    }
    else
    {
        loggers = [loggers stringByAppendingFormat:@",%@",[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 0)]];
        invertors = [invertors stringByAppendingFormat:@",%@",[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 1)]];
    }
} 

sqlite3_reset(statement);

if (isEmpty == YES)
{
    return nil;
}

[dictionary setValue:[NSString stringWithString:[plantsList stringByReplacingOccurrencesOfString:@"'" withString:@""]] forKey:@"plants"];
[dictionary setValue:loggers forKey:@"loggers"];
[dictionary setValue:invertors forKey:@"invertors"];

return dictionary;

}

此查询在代码中没有返回任何内容，但随后我在Firefox的SQLite Manager中为同一个数据库执行相同的查询，它返回正确的数据。拜托，帮我找错，我真的很累。

以下是我在Manager中的查询：

SELECT loggerID, invertorID FROM records WHERE presetID=1 AND plantID IN ('3','2','1','6','5','4')

以下是代码中的记录值：

preset: 1

plants: '3','2','1','6','5','4'

非常感谢！

Answer 1

我最近一直致力于类似的查询。

我有一个存储ID列表的NSMutableArray。我使用函数componentsJoinedByString将它们作为字符串连接起来。

然后我有一个NSString对象，它使用stringWithFormat函数保存我的SQL语句。

因此，生成SQLite查询的代码可以是：

NSString * query = [NSString stringWithFormat:@"SELECT loggerID, invertorID FROM records WHERE presetID IN (%d) AND plantID IN (%@)",presetID,[plantsList componentsJoinedByString:@","]];

希望这有帮助。

针对iPhone中的多个参数的SQLITE SELECT IN问题

1 个答案: