The formats CSV [[!RFC4180]] (comma separated values)
and TSV [[!IANA-TSV]] (tab separated values)
provide simple, easy to process formats for the transmission of tabular data.
They are supported as input datat formats to many tools, particularly spreadsheets.
This document describes their use for expressing SPARQL query results from
SELECT queries.
This document describes two simple additional results formats that have been found to be convenient in practice when consuming data obtained with SPARQL. They complement the other standard formats in XML and in JSON.
The set of SPARQL 1.1 Recommendations comprises:
This document was produced by the SPARQL Working Group, which is part of the W3C Semantic Web Activity.
This document describes CSV and TSV formats for expressing
the results of a SPARQL SELECT query.
They provide lowest common denominator
formats between systems using different
implementation technologies.
Other formats for expression SPARQL results are the SPARQL XML Results Format [[RDF-SPARQL-XMLRES]] and SPARQL JSON Results Format [SPARQL11-JSON-RES]. Each format is useful in different application scenarios.
The SPARQL Results CSV Results Format is a lossy encoding of a table of results. It does not encode all the details of each RDF term in the results but instead just gives a string without indicating the type of the term (IRI, Literal, Literal with datatype, Literal with language, or blank node). This makes it simple to consume data, such as text and numbers, in applications without needing to understand the details of RDF. In some applications, guesses as to which elements are hyperlinks are made pragmatically, for example, guessing that strings starting "http://" are links.
The SPARQL Results TSV Results Format does encode the details of RDF terms in the results table by using the syntax that SPARQL [SPARQL11-QUERY] and Turtle [[!TURTLE]] use. An application receiving a TSV-encoded results set can split each line into elements of the result row, and extract all the details it wishes to process of the RDF terms by simple string processing, without a complete XML or JSON parser required by the more complex SPARQL result formats.
When this document uses the words MUST, MUST NOT, SHOULD, SHOULD NOT, MAY and RECOMMENDED, they must be interpreted as described in RFC 2119 [[!RFC2119]].
The following artificial example is used to illustrate the features of serializing results in each format.
| x | literal | Comment (not part of the table) |
|---|---|---|
| <http://example/x> | String | An IRI and a string consisting of characters S-t-r-i-n-g |
| <http://example/x> | String-with-dquote" | String with a double quote in it. |
| _:b0 | Blank node | Blank node |
| Missing 'x' | No RDF term for the x column | |
| This row has no terms in it. | ||
| <http://example/x> | No term in the literal column. | |
| _:b1 | "String-with-lang"@en | An RDF literal with a language tag |
| _:b1 | 123 | An RDF literal, datatype xsd:integer, and lexical form 123. |
The SPARQL results formats described here confirm to the formal specifications of the relevant formats, Comma Separated values (CSV) [[!RFC4180]] and Tab Separated Value (TSV) [[!IANA-TSV]].
Systems providing these formats should note that the content types for CSV is text/csv and for TSV text/tab-separated-values. Being text/*, the default character set is US-ASCII. The charset parameter SHOULD be used in conjunction with SPARQL Results; UTF-8 is recommended: text/csv; charset=utf-8 and text/tab-separated-values; charset=utf-8.
The end-of-line in CSV is CRLF i.e. Unicode codepoints 13 (0x0D) and 10 (0x0A).
The end-of-line in TSV is EOL i.e. Unicode codepoint 10 (0x0A).
Applications reading these formats are advised to cope with both CRLF and LF as end of line markers and not rely on conformance to the formal specifications.
In the SPARQL Results CSV Format, the results table is serialized as one line listing the variables in the results, using the CSV header line, followed by one line for each query solution (a line may end up split by newlines in the data). Values in the results are strings, for URIs, literals and blank nodes, together with numbers when the literals are of numeric XSD datatype.
The first line of a SPARQL CSV Results Format response is the header line giving the names of the variables used in the result set. The header line consists of the variable names, without leading ?, separated by commas.
While the text/csv format does not require a header row, the SPARQL CSV Results Format MUST use a header row. If the content type parameter header is used, it MUST be header=present.
The remaining rows are the values of the results, with each binding determined by the position in the row, corresponding to the entry in the header line.
If a variable is not bound, an empty field is used (e.g. ,,). Each row MUST have the same number of fields, with each field corresponding to a binding to the variable in the header line in the same field position.
The entry in each field is the string corresponding to the RDF term value. (c.f. SPARQL STR()) without syntax to denote what kind of term it is. The encoding quoting rules of CSV format must be used.
Blank nodes use the _:label form from Turtle and SPARQL. Use of the same label indicates the same blank node within the results but has no significance outside the results.
Fields containing any of " (QUOTATION MARK, code point 34, 0x22 in Unicode[[UNICODE]]), , (COMMA, code point 44, 0x2C), LF (code point 10, 0x0A) or CR (code point 13, 0x0D) must be quoted using the quoting mechanism of RFC4180 [[!RFC4180]]. Fields are limited by a pair of quotation marks " (code point 0x22). Within quote strings, all characters except ", including new line characters have their exact meaning - newlines do not end a CSV record. " is written using a pair of quotation marks "".
The standard CSV format does not distinguish between missing values and empty strings. The SPARQL 1.1 CSV Results Format uses the same representation for unbound variables as for variables bound to an empty string literal. The other SPARQL Result formats (based on JSON, TSV or XML) can be used if this distinction is required.
x,literal http://example/x,String http://example/x,"String-with-dquote""" _:b0,Blank node ,Missing 'x' , http://example/x, _:b1,String-with-lang _:b1,123
In the SPARQL Results TSV Format, the results table is serialized as one line listing the variables in the results, followed by one line for each query solution. All RDF terms used in the format are encoded in the format specified by Turtle [[TURTLE]] except that the triple quoted forms for the lexical part of literals MUST NOT be used. These forms would allow raw newlines and tabs that form part of the TSV format. A TSV format SPARQL result set must use the single quoted literal forms, together with any necessary escapes such as \t, \n and \r.
The results table is serialized as one line listing the variables in the results, followed by one line for each query solution. This first line is required by the TSV format [[!IANA-TSV]], unlike CSV, where it is optional.
Variables are serialized in SPARQL syntax, using question mark ? character followed by the variable name.
Each row of the result set is serialized by sequence of RDF terms in SPARQL syntax, separated by a tab (Horizontal Tab, Unicode codepoint 9) character.
If a variable is not bound in a row, an empty field is used. Each row MUST have the same number of fields, corresponding to the variables listed in the first row.
The SPARQL Results TSV Results Format serializes RDF terms in the results table by using the syntax that SPARQL [SPARQL11-QUERY] and Turtle [[TURTLE]] use.
IRIs enclosed in <...>, literals are enclosed with double quotes "..." or single quotes ' ...' with optional @lang or ^^ for datatype. The quotes around the lexical form is required. Tab, newline and carriage return characters (Unicode codepoints 0x09, 0x0A (line feed) and 0x0D (Carriage Return)) are encoded in strings as \t, \n and \r respectively. The long string forms using triple quotes """ and ''' MUST NOT be used.
The abbreviated forms for numbers (XSD integers, decimals and doubles) SHOULD be used.
Blank nodes use the _:label form from Turtle and SPARQL. Use of the same label indicates the same blank node within the results but has no significance outside the results.
Writing <TAB> for a raw tab character (Unicode code point 9):
?x<TAB>?literal <http://example/x><TAB>"String" <http://example/x><TAB>"String-with-dquote\"" _:blank0<TAB>"Blank node" <TAB>"Missing 'x'" <TAB> <http://example/x><TAB> _:blank1<TAB>"String-with-lang"@en _:blank1<TAB>123
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