Error of text2ltree

Error of text2ltree I can't use text2ltree. Any suggestion?

SELECT tex开发者_Go百科t2ltree(to_char(243, '09999999'))

********** Error **********

ERROR: syntax error at position 0 SQL state: 42601

---

This looks like it is caused by leading whitespace being returned by to_char. To fix, use ltrim:

SELECT text2ltree(ltrim(to_char(243, '09999999'))) 

---

Try

SELECT FROM text2ltree(to_char(243, '09999999'))