Firebird Documentation IndexFirebird 2.5 Language Ref. UpdateExternal functions (UDFs) → ltrim
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ltrim

Library: ib_udf

Changed in: 1.5, 1.5.2, 2.0

Better alternative: Internal function TRIM()

Description: Returns the input string with any leading space characters removed. In new code, you are advised to use the internal function TRIM instead, as it is both more powerful and more versatile.

Result type: VARCHAR(n)

Syntax (unchanged): 

ltrim (str)

Declaration: 

DECLARE EXTERNAL FUNCTION ltrim
   CSTRING(255) NULL
   RETURNS CSTRING(255) FREE_IT
   ENTRY_POINT 'IB_UDF_ltrim' MODULE_NAME 'ib_udf'

The above declaration is from the file ib_udf2.sql. The NULL after the argument is an optional addition that became available in Firebird 2. If the argument is declared with the NULL keyword, the engine will pass a NULL argument value unchanged to the function. This leads to a NULL result, which is correct. Without the NULL keyword (your only option in pre-2.0 versions), NULL is passed to the function as an empty string and the result is an empty string as well.

For more information about passing NULLs to UDFs, see the note at the end of this book.

Notes: 

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Firebird Documentation IndexFirebird 2.5 Language Ref. UpdateExternal functions (UDFs) → ltrim