-- Select one full query at a time and paste into the Relational Algebra Editor of Relax
-- Selection

σ enr>12000 (College)

σ yCard='no' (Player)

-- Projection

π pID,yCard (Player)

π pID,pPos,dec (Tryout)

-- Selection & Projection together

π pID, pName (σ yCard='yes' (Player))

π cName,pPos (σ dec='yes' (Tryout))

-- Cartesian Product
(College) ⨯ (Player)

-- Difference 1
(π pID (σ cName='LSU'∧ pPos='goalie'∧ dec='no' (Tryout))) - 
(π pID (σ cName='ASU'∧ pPos='goalie' (Tryout)))

-- Difference 2
(π cName (College)) - (π cName (σ dec='yes' (Tryout)))

-- Union
(π pID (σ cName='LSU'∧pPos='goalie'∧dec='yes' (Tryout))) ∪ 
(π pID (σ cName='ASU'∧pPos='goalie'∧dec='no' (Tryout)))

-- Intersect
(π pID (σ cName='LSU'∧pPos='goalie'∧dec='yes' (Tryout))) ∩
(π pID (σ cName='ASU'∧pPos='goalie'∧dec='no' (Tryout)))

-- Rename
π HS (Player) - π Player.HS (σ Player.HS>s.HS ((Player) ⨯ ρ s (Player)) )

-- Division
(π pName,vName (PlayerGoals)) ÷ (π vName (Venues)) 
(π pName,vName (σ Goals>0 (PlayerGoals))) ÷ (π vName (Venues)) 

-- Example
π pName,HS ((σ HS>1000 (Player))∩(σ yCard='yes' (Player)))

-- Assignment
FSUGT=(π pID (σ cName='FSU' ∧ pPos='striker' ∧ dec='yes' (Tryout)))
NOTFSUGT=(π pID (σ cName≠'FSU' ∧ pPos='striker' (Tryout)))
FSUYOG = FSUGT-NOTFSUGT
FSUYOG

-- Natural Join 1
π pName,cName (σ yCard='no' ((Player)⨝(Tryout)))

-- Natural Join 2
π pName (σ HS<1000∧pPos='mid'∧dec='no'∧enr>10000 ((College)⨝(Tryout)⨝(Player)))

-- Natural Join 3
π pID, pName (((π pID (Player))-(π pID (Tryout)))⨝(Player))

-- Theta join
π pName (((College)⨝(Tryout)) ⨝ state=HSst (PlayerSt))

-- Rename
S = ρ X (PlayerStat) ⨝ X.Game=Y.Game ρ Y (PlayerStat)
π X.Jersey σ (X.Pts>Y.Pts)∧(Y.Jersey=10) (S)

-- 
Truck ⨝(Truck.MaxTow>=Trailer.Weight) Trailer