字串

字串字面值可以使用任何匹配的奇數個單引號或雙引號：

from artists
derive {
  single        =   'hello world',
  double        =   "hello world",
  double_triple = """hello world""",
}

SELECT
  *,
  'hello world' AS single,
  'hello world' AS double,
  'hello world' AS double_triple
FROM
  artists

引用和轉義字元

To quote a string containing quote characters, use the “other” type of quote, or use the escape character \, or use more quotes.

from artists
select {
  other   = '"hello world"',
  escaped = "\"hello world\"",
  triple  = """I said "hello world"!""",
}

SELECT
  '"hello world"' AS other,
  '"hello world"' AS escaped,
  'I said "hello world"!' AS triple
FROM
  artists

字串可以包含 JSON 標準定義的任何轉義字元序列。

from artists
derive escapes = "\tXYZ\n \\ "                            # tab (\t), "XYZ", newline (\n), " ", \, " "
derive world = "\u{0048}\u{0065}\u{006C}\u{006C}\u{006F}" # "Hello"
derive hex = "\x48\x65\x6C\x6C\x6F"                       # "Hello"
derive turtle = "\u{01F422}"                              # "🐢"

SELECT
  *,
  '	XYZ
 \ ' AS escapes,
  'Hello' AS world,
  'Hello' AS hex,
  '🐢' AS turtle
FROM
  artists

其他字串格式

• F-字串 - 從一組欄位或值建立新字串。
• R-字串 - 不含任何形式轉義的字串的原始字元。
• S-strings - Insert SQL statements directly into the query. Use when PRQL doesn’t have an equivalent facility.

[!WARNING] 目前 PRQL 允許使用單一字元或多個字元引號的多行字串。在未來版本中，使用單一字元引號的字串可能會改變。

[!NOTE] These escape rules specify how PRQL interprets escape characters when compiling strings to SQL, not necessarily how the database will interpret the string. Dialects interpret escape characters differently, and PRQL doesn’t currently account for these differences. Please open issues with any difficulties in the current implementation.

轉義序列

除非存在 r 前綴，否則字串字面值中的轉義序列將按照類似於標準 C 所使用的規則進行解釋。公認的轉義序列是：