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我试图理解下面的正则表达式,但我无法理解“@”符号的功能。
@(GROUP[[:space:]]+BY|HAVING|SELECT[[:space:]]+DISTINCT)[[:space:]]+@i
作为答案,它们是正则表达式分隔符。
它们是必需的,其他常见的分隔符是 / 或 #