hello everyone

i am new to compiler construction. I am studying lex and yacc. As a test program i have developed a small parser to parse SQL (to a very limited extent).

What i have understood is that yacc allows you to do syntactic analyses. for example

selquery:
TOK_SELECT targetlist TOK_FROM targetlist
{
//some actions
}

What i ve understood by evaluating some open source products is that you are required to construct some sort of a tree (some products call it a parse tree) here.

I need a link to how constructs execution trees when using yacc.
Are there any standards or tutorials available in this context, or such trees are
totally arbitrary

thank you