Question

Ok I know little about SQL so bear with me…

I’m trying to see if certain values exist in a third level table and I don’t know how to go about it. Here is the scenario…

I have a Accident table that holds accident information. It has 3 one-to-many child tables (Units, Occupants, NonMotorists). An each of those child tables have their own many-to-many child table (Alcohol). I need to be able to have some way of seeing if a range of values exists in a field in those Alcohol tables. Here is watered down version of what my structure for the tables looks like…

--tblAccident--_  
PK_AccidentNumber    

--tblAccidentUnit--  
PK_PrimaryKey  
FK_AccidentNumber  

--tblAccidentOccupant--    
PK_PrimaryKey  
FK_AccidentNumber

--tblAccidentNonMotorist--  
PK_PrimaryKey  
FK_AccidentNumber

--tblAccidentUnitAlcohol--  
PK_PrimaryKey  
FK_ForeignKey  
AlcoholValue <---- THIS IS WHAT I NEED TO SEARCH   

--tblAccidentOccupantAlcohol--  
PK_PrimaryKey  
FK_ForeignKey  
AlcoholValue <---- THIS IS WHAT I NEED TO SEARCH   

--tblAccidentNonMotoristAlcohol--  
PK_PrimaryKey  
FK_ForeignKey  
AlcoholValue <---- THIS IS WHAT I NEED TO SEARCH 

---

I hope this makes some sense as to what i am trying to accomplish. thank you

Answer 1

I assume you just want to get info from the third level table if the range exists.

Try the query given below:

Since the database is not specified am not sure if the BETWEEN operator in your database would includes the test values.

SELECT  AccidentNumber, 'AccidentUnit' AS TableFound, c.PrimaryKey AS TableKeyValue
  FROM  tblAccident a INNER JOIN tblAccidentUnit b
      ON    a.AccidentNumber = b.AccidentNumber INNER JOIN tblAccidentUnitAlcohol c
        ON  b.PrimaryKey = c.ForeignKey
     AND    c.AlcoholValue BETWEEN <RANGE_START> AND <RANGE_END>
UNION       
SELECT  AccidentNumber, 'AccidentOccupant' AS TableFound, c.PrimaryKey AS TableKeyValue
  FROM  tblAccident a INNER JOIN tblAccidentOccupant b
      ON    a.AccidentNumber = b.AccidentNumber INNER JOIN tblAccidentOccupantAlcohol c
        ON  b.PrimaryKey = c.ForeignKey
     AND    c.AlcoholValue BETWEEN <RANGE_START> AND <RANGE_END>
UNION
SELECT  AccidentNumber, 'AccidentNonMotorist' AS TableFound, c.PrimaryKey AS TableKeyValue
  FROM  tblAccident a INNER JOIN tblAccidentNonMotorist b
      ON    a.AccidentNumber = b.AccidentNumber INNER JOIN tblAccidentNonMotoristAlcohol c
        ON  b.PrimaryKey = c.ForeignKey
     AND    c.AlcoholValue BETWEEN <RANGE_START> AND <RANGE_END>