Java and SQL implementations take values between two characters

Java

String str = "abcdefg";
String result = str.substring(str.indexOf(">")+1, str.lastIndexOf("<"));

StringUtils.substringBefore( " abcdec " ,  " c " ); 

The result is: ab here is based on the first "c".

StringUtils.substringBeforeLast( " abcdec " ,  " c " ) 

The result is: abcde is based on the penultimate "c".

SQL

Intercept "*" and previous characters

In sql, you can intercept special characters by using the following function:

substr ( str,instr(str,'*',1)+1)

Among them, substr function and instr function are used.

1. substr (string, start_position, [length]) Find a substring and return a string

The first parameter represents the string to be truncated, the second represents the starting position, and the third represents the length of the truncation, which can be omitted.

2. instr (string, subString, position, ocurrence) Find the position of the string

The first parameter represents the source string, the second is the character to be found, the third is the starting position to be found, and the fourth is the character to be found.

Take that information between two character in a field

1. As follows

substring(a.specifications,charindex(':',a.specifications,charindex(';',specifications))+1,1)

SQL error report

FUNCTION db.charindex does not exist

2. Use the substring_index syntax

Usage rules:

substring_index ("String of useful part to be intercepted", "Character by which data is intercepted", position of intercepted character N)

Specific to intercept the N comma before the part of the characters, in the string with comma as the index, get the characters of different index bits.

N can be negative and represents the string after the penultimate N index character. (If you have a minus sign, you can look at the whole character upside down, and it is still the part before the N character.)

Specific examples:

First assume that the string to be intercepted is "192; 168; 8; 203", where the interception is based on the semicolon: ";"

The results are as follows:

Take the string before the first comma:

SELECT SUBSTRING_INDEX( ' 192;168;8;203',';',1);
==> The result is:  192

Take the part after the last comma:

SELECT SUBSTRING_INDEX( ' 192;168;8,203',';',-1);
==> The result is:  203

Take the part of the string before the second comma and after the last comma

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX( ' 192;168;8;203',';',2),';',-1);
==> The result is:  168

Take the part of the string after the penultimate comma, and then go to the part before the first comma in this part:

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX( ' 192;168;8,203',';',-2),';',1);
==>  The result is: 8

java Two strings intersect

Take the intersection of two strings

public static void checkCommom(String str1, String str2) {        
HashSet<String> result = new HashSet<String>();
        int length1 = str1.length();
        int length2 = str2.length();
        for (int i = 0; i < length1; i++) {
            for (int j = 0; j < length2; j++) {
                String char1 = str1.charAt(i) + "";
                String char2 = str2.charAt(j) + "";
                if (char1.equals(char2))
                {
                    result.add(char1);
                }
            }
        }
        
        Iterator<String> it = result.iterator();
        while (it.hasNext()) {
            String value = it.next();
            System.out.print(value);
        }
    }