PostgreSQL正则表达式替换文本字段

Question

Hi guys I have question about regex, can you help me extract date from text like:

Start   20130918 14:35:00

I wan extract 20130918 only from text. I've tried something like this:

regexreplace(Start('\s+\w{5}\d{8}\s',''))

Answer 1

对于此类问题，最好使用子字符串而不是regex_replace：

select substring('Start   20130918 14:35:00' from '[0-9]{8}')

Answer 2

You can use the following expression for matching the line:

Start\s+([0-9]{8})\s.*

and then a replacement string: \\1 .

NOTE: You might need to double escape each backslash if you are passing the expression as a string, so you might need to use:

Start\\s+([0-9]{8})\\s.*

EDIT: You can use the following statement:

SELECT regexp_replace('Start 20130918 14:35:00','Start\s+([0-9]{8})\s.*','\1')

and here is an SQL Fiddle Demo