TO_CHAR函数详解

文档地址：http://docs.oracle.com/cd/B19306_01/olap.102/b14346/dml_x_stddev018.htm#i78638

 

Return Value

TEXT

Syntax

TO_CHAR(datetime-exp, [datetime-fmt,] [optionsetting])

or

TO_CHAR(num-exp,[num-fmt,] [nlsparams])

or

TO_CHAR(ntext-exp)

 

Notes

HowTO_CHAR Handles Numerical Data Types

The TO_CHAR function converts INTEGER, SHORTINTEGER,LONGINTEGER, DECIMAL, and SHORTDECIMAL values to NUMBER beforeconverting them to TEXT. Thus, TO_CHAR converts NUMBER valuesfaster than other numerical data types.

 

Possible Effects of TO_CHARRounding

 

All number format models cause the number to be roundedto the specified number of significant digits.

---所有数字格式模式导致数字会被四舍五入成指定数量的有效数字。

 

Table 25-3, "Possible Effects of Rounding" identifies some ofthe effects of rounding.

Table25-3 Possible Effects of Rounding

IF num-expTHEN the returnvalue

has more significant digits to the left of the decimalplace than are specified in the format,

--如果小数位置向左的有效数位超过在格式中指定的数位，

appears as pound signs (#).

--那么返回值将是井号(#)

is a very large positive value that cannot be represented in thespecified format,

is a tilde (~).

is a very small negative value that cannot be represented in thespecified format,

is a negative sign followed by a tilde (-~).