Oracle SUBSTRB() Function

The Oracle (PL/SQL) SUBSTRB() function is used to extract a substring from a string starting from specified position. This function calculates length of the substring using bytes instead of characters of the input string.

Syntax

SUBSTRB(string, start, length)

Parameters

`string`	`Required.` Specify the string to extract from. It can be any of the datatypes CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB.
`start`	`Required.` Specify the start position. It can be both a positive or negative number. If it is a positive number, this function extracts from the beginning of the string. If it is a negative number, this function extracts from the end of the string. If it is 0, then it is treated as 1. Note that the first position in string starts with 1.
`length`	`Optional.` Specify the length of the substring to extract. If omitted, the whole string will be returned (from the start position). If it is less than 1, the function returns null.

Return Value

Returns the substring extracted from specified string.

Example 1:

The example below shows the usage of SUBSTRB() function.

SUBSTRB('AlphaCodingSkills.com', 1)
Result: 'AlphaCodingSkills.com'

SUBSTRB('AlphaCodingSkills.com', 6)
Result: 'CodingSkills.com'

SUBSTRB('AlphaCodingSkills.com', 6, 6)
Result: 'Coding'

SUBSTRB('AlphaCodingSkills.com', -4, 4)
Result: '.com'

Example 2:

Consider a database table called Employee with the following records:

PhoneNumber	EmpID	Address
+33-147996101	1	Grenelle, Paris, France
+31-201150319	2	Geuzenveld, Amsterdam, Netherlands
+86-1099732458	3	Yizhuangzhen, Beijing, China
+65-67234824	4	Yishun, Singapore
+81-357799072	5	Koto City, Tokyo, Japan

In the query below, the SUBSTRB() function is used to extract the country code from the PhoneNumber column records.

SELECT Employee.*, 
SUBSTRB(PhoneNumber, 2, 2) AS CountryCode 
FROM Employee;

This will produce the result as shown below:

PhoneNumber	EmpID	Address	CountryCode
+33-147996101	1	Grenelle, Paris, France	33
+31-201150319	2	Geuzenveld, Amsterdam, Netherlands	31
+86-1099732458	3	Yizhuangzhen, Beijing, China	86
+65-67234824	4	Yishun, Singapore	65
+81-357799072	5	Koto City, Tokyo, Japan	81

❮ Oracle Functions