PgQuery.parse("SELECT 1")

=> #<PgQuery::ParserResult:0x00007fb69a958820
  @query="SELECT 1",
  @tree=<PgQuery::ParseResult:
    version: 130002,
    stmts: [
      <PgQuery::RawStmt:
        stmt: <PgQuery::Node:
          select_stmt: <PgQuery::SelectStmt:
            distinct_clause: [],
            target_list: [
              <PgQuery::Node:
                res_target: <PgQuery::ResTarget:
                  name: "",
                  indirection: [],
                  val: <PgQuery::Node:
                    a_const: <PgQuery::A_Const:
                      val: <PgQuery::Node:
                        integer: <PgQuery::Integer: ival: 1>
                      >,
                      location: 7
                    >
                  >,
                  location: 7
                >
              >
            ],
            from_clause: [],
            group_clause: [],
            window_clause: [],
            values_lists: [],
            sort_clause: [],
            limit_option: :LIMIT_OPTION_DEFAULT,
            locking_clause: [],
            op: :SETOP_NONE,
            all: false
          >
        >,
        stmt_location: 0,
        stmt_len: 0
      >
    ]
  >,
  @warnings=[]>

parsed_query = PgQuery.parse("SELECT * FROM users")

# Modify the parse tree in some way
parsed_query.tree.stmts[0].stmt.select_stmt.from_clause[0].range_var.relname = 'other_users'

# Turn it into SQL again
parsed_query.deparse
=> "SELECT * FROM other_users"

# Normalizing a query (like pg_stat_statements in Postgres 10+)
PgQuery.normalize("SELECT 1 FROM x WHERE y = 'foo'")

=> "SELECT $1 FROM x WHERE y = $2"

# Parsing a normalized query (pre-Postgres 10 style)
PgQuery.parse("SELECT ? FROM x WHERE y = ?")

=> #<PgQuery::ParserResult:0x00007fb69a97a5d8
  @query="SELECT ? FROM x WHERE y = ?",
  @tree=<PgQuery::ParseResult: ...>,
  @warnings=[]>

PgQuery.parse("SELECT ? FROM x JOIN y USING (id) WHERE z = ?").tables

=> ["x", "y"]

PgQuery.parse("SELECT ? FROM x WHERE x.y = ? AND z = ?").filter_columns

=> [["x", "y"], [nil, "z"]]

PgQuery.parse("SELECT 1").fingerprint

=> "50fde20626009aba"

PgQuery.parse("SELECT 2; --- comment").fingerprint

=> "50fde20626009aba"

# Faster fingerprint method that is implemented inside the native C library
PgQuery.fingerprint("SELECT ?")

=> "50fde20626009aba"

PgQuery.scan('SELECT 1 --comment')

=> [<PgQuery::ScanResult: version: 130002, tokens: [
<PgQuery::ScanToken: start: 0, end: 6, token: :SELECT, keyword_kind: :RESERVED_KEYWORD>,
<PgQuery::ScanToken: start: 7, end: 8, token: :ICONST, keyword_kind: :NO_KEYWORD>,
<PgQuery::ScanToken: start: 9, end: 18, token: :SQL_COMMENT, keyword_kind: :NO_KEYWORD>]>,
 []]