Oracle Regular expression Analysis and digital regularization (1/2)

the square Bracket expression shows

Square Bracket Expression	Describe
[[: Alnum:]]	Characters mixed with letters and numbers
[[: Alpha:]]	Alphabetic characters
[[: Cntrl:]]	Control characters
[[:d Igit:]]	numeric characters
[[: Graph:]]	Image characters
[[: Lower:]]	Lowercase alphabetic characters
[[:p rint:]]	Print characters
[[:p unct:]]	Punctuation characters
[[: Space:]]	Space characters
[[: Upper:]]	Uppercase characters
[[: Xdigit:]]	hexadecimal numeric characters

l Meta character

description

TD valign= "Top" "width=" >

align= meta character
*	0
+	1
{m}	m is an integer. It finds exactly m occurrences of the given subexpression in the text
{n}?	The previous string only occurs once when the match
{m,}	m is an integer. It finds at least m occurrences of the given child expression in the text
{N,}?	matches the preceding string at least N Times
	< Font face= "Times New Roman" >m and n is an integer. It finds the m n Span Times New Roman '; Mso-hansi-font-family: ' Times Roman ' ">
{N,m}	match the preceding string to at least N times, but not more than m Times
C	Query operations are case sensitive
I	Query operation does not distinguish between flood writing
M	a query on a multiline string that, when the source string contains more than a row, allows the query to be used ( ^ the start of the pattern matching string
N	Usually match a single character or a new row
X	when you need to ignore whitespace characters in a regular expression, use the arguments ' x '
A	Matches the head of a string, not the beginning of the line, so multiple lines of string cannot match each row
D	Match any number of characters
D	Match any non-numeric character
S	Match any white space character
S	Match any non-whitespace character
W	matches any character and number. The difference between the character and [: alnum:] is w including the underscore character
W	Match any non-empty string
*	wildcard characters. Finds records that contain 0 or more occurrences of a given subexpression in the text
+	find out what's included in the text 1 or multiple occurrences of a given subexpression
？	find out what's included in the text 0 Times or 1 The record that appears with the given child expression
.	Match any character in the text
^	Anchor. If the expression after the character appears at the beginning of the line, the match succeeds
$	Anchor. If the expression after the character appears at the beginning of the line, the match succeeds
|	Separator , use methods and or same
(....)	Grouping sub-expressions

Create or Replace function Isnumber (valid_str in VARCHAR2)
return number
Is
Cursor Valid_number is
Select 1 from dual where regexp_like (Valid_str, ' ^[+-]?d+ (. d)? d*$ ');
Isnumber_ Valid_number%rowtype;
Begin
Open valid_number;
Fetch valid_number into Isnumber_;
if (Valid_number%found) then
Close Valid_number;
return 1;
Else
Close Valid_number;
return 0;
End If;
End Isnumber;

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