Export CSV file number will automatically change the method of scientific counting

To export data to Excel files into scientific notation questions:

Analysis: The CSV file exported by the program, when the field has a relatively long number of fields exist, in the use of Excel software to view the CSV file will become the form of scientific and technological law.
In fact, this question is not related to what language to export CSV files. When Excel displays a number, if the number is greater than 12 digits, it is automatically converted to scientific notation; If the number is greater than 15 digits, it is not only used in the scientific and technical law, but it will retain only a high of 15 bits, and the other bits are 0.

Workaround: (as long as the number field followed by the display of invisible characters, the end of the String plus tab "T")

For example: The PHP program can be so judged, note must be "\ T", not ' t '.
Is_numeric ($exporVal)? $exporVal. "T": $exporVal;