SPARQL 如何让 DAY/MONTH 总是 return 2 位数

Question

我的 SPARQL 查询中有一个日期时间，我想将其转换为日期。因此我这样做：

 BIND(CONCAT(YEAR(?dateTime), "-",MONTH(?dateTime), "-", DAY(?dateTime)) as ?date)

这部分代码有效，但 returns 例如 2022-2-3，我希望它是 2022-02-03。如果日期时间是 2022 年 11 月 23 日，则不会有任何变化。

Answer 1

您可以获取从 YEAR、MONTH 和 DAY 函数返回的整数，并用适当数量的零填充它们（在将它们转换为字符串之后） :

PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT * WHERE {
    BIND(2022 AS ?yearInt) # this would come from your YEAR(?dateTime) call
    BIND(2 AS ?monthInt)   # this would come from your MONTH(?dateTime) call
    BIND(13 AS ?dayInt)    # this would come from your DAY(?dateTime) call

    # convert to strings
    BIND(STR(?yearInt) AS ?year)
    BIND(STR(?monthInt) AS ?month)
    BIND(STR(?dayInt) AS ?day)

    # pad with zeros
    BIND(CONCAT("00", ?year) AS ?paddedYear)
    BIND(CONCAT("0000", ?month) AS ?paddedMonth)
    BIND(CONCAT("00", ?day) AS ?paddedDay)

    # extract the right number of digits from the padded strings
    BIND(SUBSTR(?paddedYear, STRLEN(?paddedYear)-3) AS ?fourDigitYear)
    BIND(SUBSTR(?paddedDay, STRLEN(?paddedDay)-1) AS ?twoDigitDay)
    BIND(SUBSTR(?paddedMonth, STRLEN(?paddedMonth)-1) AS ?twoDigitMonth)
    
    # put it all back together
    BIND(CONCAT(?fourDigitYear, "-", ?twoDigitMonth, "-", ?twoDigitDay) as ?date)
}

Answer 2

@gregory-williams 给出了一个可移植的答案。另一种方法是 F&O 中的函数（XPath 和 XQuery 函数和运算符 3.1）“fn:format-....”

我不确定各种三元组的覆盖范围 - Apache Jena 提供 fn:format-number，这是问题所需要的，但不是 fn-format-dateTime 等

见
https://www.w3.org/TR/xpath-functions-3/#formatting-the-number
https://www.w3.org/TR/xpath-functions-3/#formatting-dates-and-times

例如：

fn:format-number(1,"000") returns 字符串“001”.

Apache Jena 也有一个本地扩展 afn:sprintf 使用 sprintf 的 C 或 Java 语法：

afn:sprintf("%03d", 1) returns "001".

SPARQL 如何让 DAY/MONTH 总是 return 2 位数

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