short int、long、float、double使用问题说明
在Access数据导出到DBF时遇到此问题，DBF中的字段宽度不是指Access中的字段所占字节数，而是字符数。
short int 短整型 2个字节 值范围 -32768~32767long 长整型 4个字节 值范围 -2147483648～2147483647 float 单精度 4个字节 值范围 -3.4*10(-38)～3.4*10(38)
double 双精度 8个字节 值范围 -1.7*10(-308)～1.7*10(308)
在Access数据导出到DBF时遇到此问题，DBF中的字段宽度不是指Access中的字段所占字节数，而是字符数。 在DBF中，整数与浮点数都是以字符形式存储的。例如：-3.134存储为“-3.135”，共占了6个字符。
所以
对于Access中的短整型，存储为DBF中的字段宽度为6；
对于Access中的长整型，存储为DBF中的字段宽度为11；
对于Access中的单精度，存储为DBF中的字段宽度为18，小数位为7；
对于Access中的双精度，存储为DBF中的字段宽度为24，小数位为15。
就是说，access中的单精度、双精度数据，转储到DBF中很难保证精度。
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