CSV 格式及注意事项

CSV is a delimited data format that has fields/columns separated by the comma character and records/rows separated by newlines. Fields that contain a special character (comma, newline, or double quote), must be enclosed in double quotes. However, if a line contains a single entry which is the empty string, it may be enclosed in double quotes. If a field's value contains a double quote character it is escaped by placing another double quote character next to it. The CSV file format does not require a specific character encoding, byte order, or line terminator format.

• Each record is one line terminated by a line feed (ASCII/LF=0x0A) or a carriage return and line feed pair (ASCII/CRLF=0x0D 0x0A), however, line-breaks can be embedded.
• Fields are separated by commas.

1997,Ford,E350

• In some CSV implementations, leading and trailing spaces or tabs, adjacent to commas, are trimmed. This practice is contentious and in fact is specifically prohibited by RFC 4180, which states, "Spaces are considered part of a field and should not be ignored."

1997,   Ford   , E350

same as

1997,Ford,E350

• Fields with embedded commas must be delimited with double-quote characters.

1997,Ford,E350,"Super, luxurious truck"

• Fields with embedded double-quote characters must be delimited with double-quote characters, and the embedded double-quote characters must be represented by a pair of double-quote characters.

1997,Ford,E350,"Super ""luxurious"" truck"

• Fields with embedded line breaks must be delimited by double-quote characters.

1997,Ford,E350,"Go get one now

they are going fast"

• Fields with leading or trailing spaces must be delimited by double-quote characters. (See comment about leading and trailing spaces above.)

1997,Ford,E350,"  Super luxurious truck    "

• Fields may always be delimited by double-quote characters, whether necessary or not.

"1997","Ford","E350"

• The first record in a csv file may contain column names in each of the fields.

Year,Make,Model

1997,Ford,E350

2000,Mercury,Cougar
   

[edit] Example

1997    Ford        E350                                                   ac, abs, moon                    3000.00 1999    Chevy     Venture "Extended Edition"                                                           4900.00   1996    Jeep       Grand                                                 Cherokee MUST SELL!                                                                                           air, moon roof, loaded       4799.00

The above table of data may be represented in CSV format as follows:

1997,Ford,E350,"ac, abs, moon",3000.00

1999,Chevy,"Venture ""Extended Edition""","",4900.00

1996,Jeep,Grand Cherokee,"MUST SELL!

air, moon roof, loaded",4799.00

This CSV example illustrates that:

• fields that contain commas, double-quotes, or line-breaks must be quoted,
• a quote within a field must be escaped with an additional quote immediately preceding the literal quote,
• space before and after delimiter commas may be trimmed, and
• a line break within an element must be preserved.