Re: [sqlite] Parser bug on sub joins when on right side of the join operator

[TAUZIN Mathieu]

Hi,

According to the documentation (Sqlite + standard Ansi),
queries that should be supported like :
        SELECT * 
        FROM A JOIN (B JOIN C ON B.ID = C.ID) ON A.ID = B.ID
are still not supported whereas badly formed queries like :
        SELECT * 
        FROM A JOIN (B JOIN C ON B.ID = C.ID) AS D ON A.ID = D.ID
work !

anyone to fix this ? 

Mathieu 

-----Message d'origine-----
De : sqlite-users-boun...@sqlite.org [mailto:sqlite-users-boun...@sqlite.org] 
De la part de Mathieu TAUZIN Envoyé : lundi 26 mars 2012 15:53 À : 
sqlite-users@sqlite.org Objet : [sqlite] Parser bug on sub joins when on right 
side of the join operator

Hi,
 
According to their definition 
(http://sqlite.org/syntaxdiagrams.html#single-source) , Join sources (named 
single-source) are either : 
                * a table or view with an optional alias and/or with an 
optional index
                * a sub query with an optional alias
                * a sub join (with no alias)

In SQLite parser.y source code we can find on line 496 the grammar rule 
handling those three cases (in the same order)
 
<snippet line='496'>
...
seltablist(A) ::= stl_prefix(X) nm(Y) dbnm(D) as(Z) indexed_opt(I) on_opt(N) 
using_opt(U). {
  A = sqlite3SrcListAppendFromTerm(pParse,X,&Y,&D,&Z,0,N,U);
  sqlite3SrcListIndexedBy(pParse, A, &I); }
 
seltablist(A) ::= stl_prefix(X) LP select(S) RP
                    as(Z) on_opt(N) using_opt(U). {
    A = sqlite3SrcListAppendFromTerm(pParse,X,0,0,&Z,S,N,U);
  }
 
seltablist(A) ::= stl_prefix(X) LP seltablist(F) RP
                    as(Z) on_opt(N) using_opt(U). {
    if( X==0 && Z.n==0 && N==0 && U==0 ){
      A = F;
    }else{
      Select *pSubquery;
      sqlite3SrcListShiftJoinType(F);
      pSubquery = sqlite3SelectNew(pParse,0,F,0,0,0,0,0,0,0);
      A = sqlite3SrcListAppendFromTerm(pParse,X,0,0,&Z,pSubquery,N,U);
    }
  }
...
</snippet>
 
Case 1 and 2 are handled properly but as you can see the third definition (wich 
should deal with sub joins) contains mistakes :
                #1 : It allows an as clause after the parenthesis
                #2 : on the right of a join operator (else { ... }) it 
generates a subquery instead of merging F (which is a seltabList, not a sub
query) with X into A.
 
I wish I could propose a fix but I have no skills in C/yacc.
 
Hope this will help anyway.
 
Thanks
 
 
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