从表中选择与特定列的最大值和最小值对应的所有列

Question

我有一个表，其中包含以下格式的数据：

Mand_ID Type            Sub_Type D_Freq Limit_Type      mon_freq   Val  Units
======= =======         ======== ====== ===========     =========  ==== ======= 
IAC901  TRACKING_ERROR  EX_ANTE  NA     LESS_THAN       MONTHLY    200  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     GREATER_THAN    MONTHLY    150  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     LESS_THAN       MONTHLY    450  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     GREATER_THAN_EQ MONTHLY    0    BASIS_POINTS

现在，我要选择具有max（Val）和min（Val）的行。 即我想从上表中一次选择以下两行

Mand_ID Type            Sub_Type D_Freq Limit_Type      mon_freq   Val  Units
======= =======         ======== ====== ===========     =========  ===  ======  
IAC901  TRACKING_ERROR  EX_ANTE  NA     LESS_THAN       MONTHLY    450  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     GREATER_THAN_EQ MONTHLY    0    BASIS_POINTS

注意：表中Mand_ID有许多不同的值； 我想要每个单独的Mand_ID具有最大和最小值的行。

Answer 1

select * 
from theTable t, 
     (select max(val) as max_val, min(val) as min_val from theTable) as max_min
where t.val=max_min.max_val or t.val=max_min.min_val

Answer 2

让我们假设该表是从主捆绑软件加载的文本文件：

TestText is:

Mand_ID Type            Sub_Type D_Freq Limit_Type      mon_freq   Val  Units
======= =======         ======== ====== ===========     =========  ==== ======= 
IAC901  TRACKING_ERROR  EX_ANTE  NA     LESS_THAN       MONTHLY    200  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     GREATER_THAN    MONTHLY    150  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     LESS_THAN       MONTHLY    450  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     GREATER_THAN_EQ MONTHLY    0    BASIS_POINTS

比...

// Do any additional setup after loading the view, typically from a nib.
NSString* path = [[NSBundle mainBundle] pathForResource:@"TestText"
                                                 ofType:@"txt"];
NSString* content = [NSString stringWithContentsOfFile:path
                                              encoding:NSUTF8StringEncoding
                                       error: nil];


NSArray *array = [content componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];

NSString *numberString;
int MinIndex=0,MaxIndex=0,MinVal=0,MaxVal = 0;
BOOL FirstTrackingError=YES;

for (int i=0;i<[array count];++i)
{
    if ([[array objectAtIndex:i] rangeOfString:@"TRACKING_ERROR"].location != NSNotFound)
    {

        NSRange range = [[array objectAtIndex:i] rangeOfString:@"MONTHLY"];
        NSString *substring = [[array objectAtIndex:i] substringFromIndex:NSMaxRange(range)];

        NSScanner *scanner = [NSScanner scannerWithString: substring];
        NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];

        // Throw away characters before the first number.
        [scanner scanUpToCharactersFromSet: numbers intoString:NULL];

        // Collect numbers.
        [scanner scanCharactersFromSet:numbers intoString:&numberString];


        if(FirstTrackingError == YES)
        {
            MinIndex=MaxIndex=i;
            MinVal=MaxVal=[numberString intValue];
            FirstTrackingError=NO;
        }
        else
        {
            if ([numberString intValue] > MaxVal)
            {
                MaxVal=[numberString intValue];
                MaxIndex=i;
            }
            else if ([numberString intValue] < MinVal)
            {
                MinVal=[numberString intValue];
                MinIndex=i;
            }
        }

    }

}


NSLog(@"%@",[array objectAtIndex:MinIndex]);
NSLog(@"%@",[array objectAtIndex:MaxIndex]);

NSString *result=[array objectAtIndex:MaxIndex];
result=[result stringByAppendingFormat:@"\n%@",[array objectAtIndex:MinIndex]];

NSLog(@"Result : \r\n%@",result);

The result is:

IAC901  TRACKING_ERROR  EX_ANTE  NA     LESS_THAN       MONTHLY    450  BASIS_POINTS
IAC901  TRACKING_ERROR  EX_ANTE  NA     GREATER_THAN_EQ MONTHLY    0    BASIS_POINTS