Regular Expression to get VARIABLE02 from "convert(nvarchar(10),convert(datetime,VARIABLE02 , 121), 103)"

Question

Any one can show me how to get VARIABLE02 from the string below convert(nvarchar(10),convert(datetime,VARIABLE02 , 121), 103)

convert.*(.+,(.+),.+)

The above regex is working with convert(datetime,VARIABLE02 , 121), but once in multiple instances, it would stuff up.

Thanks for advice

Bin

Answer 1

You could try using a negative lookahead to assert what follows after the second comma is not convert and capture your value in the first capturing group using a negated character class ([^,]+):

convert\([^,]+,(?!convert)([^,]+)

That would match

• convert Match literally
• \( Match opening parenthesis
• [^,]+, Match not a comma one or more times using a negated character class, then match a comma
• (?!convert) - Negative lookahead which assert that what follows is not convert
• ([^,]+) Capture in a group matching not a comma one or more times (This will contain your value)

Answer 2

You could try:

(?<=,)[a-zA-Z0-9]+(?= ?,)

Answer 3

Seems not possible by using regex itself.

The slide below give a good explanation: Can regular expressions be used to match nested patterns? Can regular expressions be used to match nested patterns?

But thanks all.