TRIM

Syntax

Description of the illustration trim.gif

Purpose

TRIMenables you to trim leading or trailing characters (or both) from a character string. Iftrim_characterortrim_sourceis a character literal,then you must enclose it in single quotes.

• If you specifyLEADING,then Oracle Database removes any leading characters equal totrim_character.

• If you specifyTRAILING,then Oracle removes any trailing characters equal totrim_character.

• If you specifyBOTHor none of the three,then Oracle removes leading and trailing characters equal totrim_character.

• If you do not specifytrim_character,then the default value is a blank space.

• If you specify onlytrim_source,then Oracle removes leading and trailing blank spaces.

• The function returns a value with datatypeVARCHAR2. The maximum length of the value is the length oftrim_source.

• If eithertrim_sourceortrim_characteris null,then theTRIMfunction returns null.

Bothtrim_characterandtrim_sourcecan be any of the datatypesCHAR,VARCHAR2,NCHAR,NVARCHAR2,CLOB,orNCLOB. The string returned is ofVARCHAR2datatype iftrim_sourceis a character datatype and a LOB iftrim_sourceis a LOB datatype. The return string is in the same character set astrim_source.

Examples

This example trims leading zeroes from the hire date of the employees in thehrschema:

SELECT employee_id,TO_CHAR(TRIM(LEADING 0 FROM hire_date))
      FROM employees
      WHERE department_id = 60;

EMPLOYEE_ID TO_CHAR(T
----------- ---------
        103 3-JAN-90
        104 21-MAY-91
        105 25-JUN-97
        106 5-FEB-98
        107 7-FEB-99

http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions199.htm#i79689

（编辑：李大同）

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