Thread: Parser Modification Problem: Get the columns of a Table

Dear Friends,

 

I am trying to modify the parser of the postgresql so as to print all the columns of a table (or to put them in a seperate file) when the parser meets an Insert Statement.

In the <gram.y> file (/src/backend/parser/gram.y) ,

 

InsertStmt:
   INSERT INTO qualified_name insert_rest
    {
     $4->relation = $3;
     $$ = (Node *) $4;
    }
  ;

I can take the table name adding the following line of code

 

printf($3->relname);

 

 

The problem is that in the insert_column_item section (see the last section below) the var n is of type ResTarget and in case of insert and select the ResTarget->Name is null and not the name of the column (in the update command everything is ok- see also the line 371 in the file parsenodes.h ...typedef struct ResTarget {....} ). Could you please tell me the way to take the names of the columns?

 

Every answer will be appreciated

Thank  You Very Much In Advance

NK

 

insert_rest:
   VALUES '(' insert_target_list ')'
    {
     $$ = makeNode(InsertStmt);
     $$->cols = NIL;
     $$->targetList = $3;
     $$->selectStmt = NULL;
    }
   | DEFAULT VALUES
    {
     $$ = makeNode(InsertStmt);
     $$->cols = NIL;
     $$->targetList = NIL;
     $$->selectStmt = NULL;
    }
   | SelectStmt
    {
     $$ = makeNode(InsertStmt);
     $$->cols = NIL;
     $$->targetList = NIL;
     $$->selectStmt = $1;
    }
   | '(' insert_column_list ')' VALUES '(' insert_target_list ')'
    {
     $$ = makeNode(InsertStmt);
     $$->cols = $2;
     $$->targetList = $6;
     $$->selectStmt = NULL;
    }
   | '(' insert_column_list ')' SelectStmt
    {
     $$ = makeNode(InsertStmt);
     $$->cols = $2;
     $$->targetList = NIL;
     $$->selectStmt = $4;
    }
  ;

insert_column_list:
   insert_column_item      { $$ = makeList1($1); }
   | insert_column_list ',' insert_column_item
     { $$ = lappend($1, $3); }
  ;

insert_column_item:
   ColId opt_indirection
    {
     ResTarget *n = makeNode(ResTarget);
     n->name = $1;
     n->indirection = $2;
     n->val = NULL;
     $$ = (Node *)n;
    }
  ;