Mysql SUBSTRING_INDEX() function

Mysql SUBSTRING_INDEX() function

MySQL SUBSTRING_INDEX() returns the substring from the given string before a specified number of occurrences of a delimiter.

The substring returned from the left of the final delimiter when the specified number is a positive number and from the right of the final delimiter when the specified number is a negative number.

If the specified number is greater than the number of occurrence of delimiter, the returned substring will be the total string. If the specified number is 0, nothing will be fetched from the given string.

Syntax:

SUBSTRING_INDEX(str, delim, count)

Argument

Name	Description
str	A string.
delim	A delimiter.
count	An integer indicating the number of occurrences of delim.

Example: MySQL SUBSTRING_INDEX() function

The following MySQL statement returns the substring form the left of the final delimiter i.e. 2nd delimiter (.) from the given string ‘www.mytestpage.info’. Counting starts from the left of the string.

Code:

SELECT SUBSTRING_INDEX('www.mytestpage.info','.',2);



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Sample Output:

mysql> SELECT SUBSTRING_INDEX('www.mytestpage.info','.',2);
+----------------------------------------------+
| SUBSTRING_INDEX('www.mytestpage.info','.',2) |
+----------------------------------------------+
| www.mytestpage                               | 
+----------------------------------------------+
1 row in set (0.02 sec)

Pictorial Presentation

Example of MySQL SUBSTRING_INDEX() function using negative count

The following MySQL statement returns the substring from the right of the final delimiter i.e. 2nd delimiter (.) from the given string ‘www.mytestpage.info’. Counting starts from the right of the string.

Code:

SELECT SUBSTRING_INDEX('www.mytestpage.info','.',-2); 



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Sample Output:

mysql> SELECT SUBSTRING_INDEX('www.mytestpage.info','.',-2); 
+-----------------------------------------------+
| SUBSTRING_INDEX('www.mytestpage.info','.',-2) |
+-----------------------------------------------+
| mytestpage.info                               | 
+-----------------------------------------------+
1 row in set (0.00 sec)

Pictorial Presentation

Example: Split an IP address into 4 respective octets using MySQL SUBSTRING_INDEX() function

The following MySQL command splits an IP address into 4 respecting octets (unit of digital information). Assume the IP addresses are stored in a sample table called 'log_file'.

mysql> SELECT ip, SUBSTRING_INDEX(ip,'.',1) AS part1, 
SUBSTRING_INDEX(SUBSTRING_INDEX(ip,'.',2),'.',-1) AS part2, 
SUBSTRING_INDEX(SUBSTRING_INDEX(ip,'.',-2),'.',1) AS part3, 
SUBSTRING_INDEX(ip,'.',-1) AS part4  FROM log_file;
+-----------------+-------+-------+-------+-------+
| ip              | part1 | part2 | part3 | part4 |
+-----------------+-------+-------+-------+-------+
| 127.0.0.1       | 127   | 0     | 0     | 1     |
| 192.128.0.15    | 192   | 128   | 0     | 15    |
| 255.255.255.255 | 255   | 255   | 255   | 255   |
+-----------------+-------+-------+-------+-------+
3 rows in set (0.00 sec)