1.2 Parser and Analyzer: How SQL Gets Its Meaning

A line like SELECT name FROM users WHERE id = 1 is just text when the client sends it. The first thing the backend does after receiving it is figure out "what do these characters mean." This chapter covers the second of the five stages we saw in 1.1.1: the parser and analyzer. By the time this stage finishes, the SQL text has been transformed twice. First into a raw parse tree that captures the grammatical structure, then into a Query tree with meaning attached after consulting the catalog. The