orcale的to_number方法

--to_number(expr)--to_number(expr,format)--to_number(expr,format,'nls-param')select to_number('0123')number1,            --converts a string to number       trunc(to_number('0123.123'),2) number2,       to_number('120.11','999.99') number3, 　　　 to_number('0a','xx') number4,        --converts a hex number to decimal       to_number(100000,'xxxxxx') number5  from dual;