SQLite: Combining an OR and AND

Question

This is continuing questions from http://stackoverflow.com/questions/3539673/sqlite-selecting-the-highest-salary

Assuming a table 'wagetable'

  name     lowhours  highhours  wage  priority 
  Default  0.0       40.0       100   0        
  Default  40.0      50.0       150   0        
  Default  50.0      70.5       154   0        
  Default  70.5      100.0      200   0        
  Brian    0.0       40.0       200   1        
  Brian    40.0      50.0       250   1        
  Brian    50.0      60.0       275   1        
  Brian    60.0      70.0       300   1        
  Brian    70.0      80.0       325   1        
  Brian    80.0      9999.0     350   1        
  Chad     0.0       40.0       130   1        
  Chad     40.0      9999.0     170   1  

I currently performing two types of queries 3-4 times a second, so performance is key, not really readability (but preferred).

This query choose the wage if and only if the $Hour is between lowhours and highhours:

SELECT wage 
FROM wagetable 
WHERE name LIKE '$Employee' OR name LIKE 'Default' 
AND '$Hour' BETWEEN lowhours AND highhours 
ORDER BY priority DESC 
LIMIT 1

This 2nd query takes off if the first failed to find $Hour between lowhours and highhours:

SELECT wage 
FROM wagetable 
WHERE name LIKE '$Employee' OR name LIKE 'Default' 
ORDER BY priority DESC, highhours DESC
LIMIT 1

I am looking to see if there could be a query where I could combine both to do the same thing in just one query

Edit:

Because I didn't correctly test the above queries.. I will tell you what I want in english and examples of answers.

It will check rather $Employee exists on the table, then use it. If it doesnt, then check for 'Default' instead. Once it knows the name, it will check to see if $Hour is between a known lowhours and highhours, if it does, SELECT that wage, if its higher than anything listed, automatically take the wage for the highest hour.

Here are some values. Please note that "sam" is not on the table, so he will be 'Default' The examples follow this format: (Name, Hour) EXPECTED ANSWER

(Sam, 1)        100
(Sam, 51)       154
(Sam, 999999)   200

(Brian, 1)      200
(Brian, 51)     275
(Brian, 999999) 350

Here is the table again so you can quick reference, remember Sam will be 'Default'

name     lowhours  highhours  wage  priority 
Default  0.0       40.0       100   0        
Default  40.0      50.0       150   0        
Default  50.0      70.5       154   0        
Default  70.5      100.0      200   0        
Brian    0.0       40.0       200   1        
Brian    40.0      50.0       250   1        
Brian    50.0      60.0       275   1        
Brian    60.0      70.0       300   1        
Brian    70.0      80.0       325   1        
Brian    80.0      9999.0     350   1      

Edit 2:

The point of this is so that you can define a table of wages where if someone gets more money than the rest, they get paid a certain amount plus overtime. If it is a standard worker, then will be get Default wages. If the $Employee is on the list, then he gets special wages.

The lowest lowhours will -always- be 0.0, The lowhours and highhours pair will -never- have any gaps (It won't allow 40-50 and then skip and do 60-70). What is uncertain is the highest highhours. Therefore is $Hour is higher than the $Employee's highest highhours, then it should use the $Employee's highest highhours's wage.

For example; If "Betty Sue" worked 200 hours, it will get Default's highest highhours wage... which is 200. Therefore the wage "Betty Sue" makes on her 200th hour is 200 per hour.

Now if Brian works 10000 hours, he will NOT earn Default's highest highhours wage...but instead he will earn Brian's highest highhours wage, which is 350.

The results of the benchmark:

This is based on 2000 queries (1000 for a match and 1000 for a default non match):

Timwi's Method: 4348 milliseconds

OMG Ponie's Method: 5843 milliseconds

My method using up to 5 queries and atleast 2: 5844 milliseconds

Answer 1

Here's what I mentioned in my comment to Alex:

SELECT s.wage
  FROM (SELECT x.wage
          FROM WAGETABLE x
         WHERE x.name LIKE '$Employee'
           AND '$Hour' BETWEEN x.lowhours AND x.highhours
        UNION ALL
        SELECT y.wage AS wage
          FROM WAGETABLE y
          JOIN (SELECT wt.name,
                       MAX(wt.highhours) AS max_hours
                  FROM WAGETABLE wt
              GROUP BY wt.name) bb ON bb.name = y.name
                                  AND bb.max_hours = y.highhours
         WHERE y.name LIKE '$Employee'
        UNION ALL
        SELECT t.wage
          FROM WAGETABLE t
         WHERE t.name = 'Default'
           AND '$Hour' BETWEEN t.lowhours AND t.highhours
        UNION ALL
        SELECT z.wage
          FROM WAGETABLE z
          JOIN (SELECT wt.name,
                       MAX(wt.highhours) AS max_hours
                  FROM WAGETABLE wt
              GROUP BY wt.name) aa ON aa.name = z.name
                                  AND aa.max_hours = z.highhours
         WHERE z.name LIKE 'Default') s
 LIMIT 1

Previously:

SELECT s.wage
  FROM (SELECT x.wage
          FROM WAGETABLE x
         WHERE x.name LIKE '$Employee'
           AND '$Hour' BETWEEN x.lowhours AND x.highhours
        UNION ALL
        SELECT y.wage
          FROM WAGETABLE y
         WHERE y.name LIKE 'Default'
           AND y.highhours = (SELECT MAX(highhours)
                                FROM WAGETABLE wt
                               WHERE wt.name = y.name)) s
 LIMIT 1

Because of selecting for a match on the user/etc is in the upper portion of the UNION, if such a record exists - it will be the first row. If there are no matches, the Default match will be the first row. The Default will always be in the resultset, hence the need for the LIMIT...

Answer 2

I believe this is the most straightforward way to do what you want:

SELECT IFNULL(
    (SELECT wage FROM WAGETABLE WHERE name LIKE '$Employee'
                 AND '$Hour' BETWEEN lowhours AND highhours),
    (SELECT wage FROM WAGETABLE WHERE name LIKE 'Default'
                 ORDER BY highhours DESC LIMIT 1)
)

It does what you describe in the other question:

• Retrieve the wage for the $Employee;
• If there is no row for the $Employee, this results in NULL, so the ISNULL kicks in;
• Only if the first result was NULL, the Default row is retrieved.

HOWEVER, I feel that I should point out that the queries you have posted in this question do something different. My query does not find a Default row that has a matching lowhours / highhours interval, it only ever returns the one with the highest highhours for Default. I don’t know whether the query in the question is really what you want, but it seems more likely, therefore here is a query that is equivalent to what you’re actually asking in this question:

SELECT IFNULL(
    (SELECT wage FROM WAGETABLE WHERE (name LIKE '$Employee' OR name='Default')
                 AND '$Hour' BETWEEN lowhours AND highhours
                 ORDER BY priority DESC LIMIT 1),
    (SELECT wage FROM WAGETABLE WHERE name LIKE '$Employee' OR name='Default'
                 ORDER BY priority DESC, highhours DESC LIMIT 1)
)