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Oracle® Database SQL Language Reference
12c Release 1 (12.1)

E17209-15
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SUBSTR

Syntax

substr::=

Description of substr.gif follows
Description of the illustration substr.gif

Purpose

The SUBSTR functions return a portion of char, beginning at character position, substring_length characters long. SUBSTR calculates lengths using characters as defined by the input character set. SUBSTRB uses bytes instead of characters. SUBSTRC uses Unicode complete characters. SUBSTR2 uses UCS2 code points. SUBSTR4 uses UCS4 code points.

char can be any of the data types CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB. The exceptions are SUBSTRC, SUBSTR2, and SUBSTR4, which do not allow char to be a CLOB or NCLOB. Both position and substring_length must be of data type NUMBER, or any data type that can be implicitly converted to NUMBER, and must resolve to an integer. The return value is the same data type as char. Floating-point numbers passed as arguments to SUBSTR are automatically converted to integers.

See Also:

Oracle Database Globalization Support Guide for more information about SUBSTR functions and length semantics in different locales

Examples

The following example returns several specified substrings of "ABCDEFG":

SELECT SUBSTR('ABCDEFG',3,4) "Substring"
     FROM DUAL;
 
Substring
---------
CDEF

SELECT SUBSTR('ABCDEFG',-5,4) "Substring"
     FROM DUAL;

Substring
---------
CDEF

Assume a double-byte database character set:

SELECT SUBSTRB('ABCDEFG',5,4.2) "Substring with bytes"
     FROM DUAL;

Substring with bytes
--------------------
CD