您可以使用捕获组并在替换中使用该组。

(,\s*)[^,]*\sAS\b\s*

说明

• (,\s*)捕获组1，匹配逗号和可选空格字符
• [^,]*匹配除逗号以外的任何字符
• \sAS\b\s*匹配一个空格字符，然后AS后跟可选空格

Regex demo|Python demo

import re
 
pattern = r"(,\s*)[^,]*\sAS\b\s*"
s = ("Select customer_name, customer_type, COUNT(*) AS volume\\nFROM table\\nGROUP BY customer_name, customer_type\\nORDER BY volume DESC\\nLIMIT 10\n")
 
print(re.sub(pattern, r"\1", s))

输出

Select customer_name, customer_type, volume\nFROM table\nGROUP BY customer_name, customer_type\nORDER BY volume DESC\nLIMIT 10

我会用途：

text = "Select customer_name, customer_type, COUNT(*) AS volume\nFROM table\nGROUP BY customer_name, customer_type\nORDER BY volume DESC\nLIMIT 10"
result = re.sub(r',\s*\S+\s+AS\b\s*', ', ', text)
print(result)

这将打印：

Select customer_name, customer_type, volume
FROM table
GROUP BY customer_name, customer_type
ORDER BY volume DESC
LIMIT 10

这里使用的正则表达式模式表示匹配：

• ,一个逗号
• \s*可选空格
• \S+非空白术语
• \s+一个或多个空白字符
• AS文字“AS”
• \b字边界
• \s*更多可选空格