How do you find a regular expression? What is a regular expression, regexp, or regex? Extracting substring matching SQL regular expression. The substring function with two parameters, substring (string from pattern), provides extraction of a substring that matches a POSIX regular expression pattern. It returns null if there is no match, otherwise the portion of the text that matched the pattern.
The pattern is a POSIX regular expression for matching substrings that should be replaced. Regex Usage, or use Substring ? However, if the pattern is like this DOE, JR. The first character of the string is at position 1. If the number of characters to be extracted from the string is not specifie the function will extract characters from the specified start position to the end of the string. Although there are multiple ways to do pattern matching in SQL, we will look at the most powerful and flexible of them all – regular expressions. I am trying to extract a substring from a text column using a regular expression , but in some cases, there are multiple instances of that substring in the string.
In those cases, I am finding that the query does not return the first occurrence of the substring. Michael Glaesemann Looks like you might want to brush up on regular expressions in general.

