问题：
oerr ora 1861
01861, 00000, "literal does not match format string"
// *Cause: Literals in the input must be the same length as literals in
// the format string (with the exception of leading whitespace). If the
// "FX" modifier has been toggled on, the literal must match exactly,
// with no extra whitespace.
// *Action: Correct the format string to match the literal.
01861, 00000, "literal does not match format string"
// *Cause: Literals in the input must be the same length as literals in
// the format string (with the exception of leading whitespace). If the
// "FX" modifier has been toggled on, the literal must match exactly,
// with no extra whitespace.
// *Action: Correct the format string to match the literal.
解决方案：
to_date('2010-5-1','YYYY-MM-DD')"