# Miscellaneous > Ask an Expert >  Unclosed quotation mark before the character string

## allievi

People,
I am generating a string Hash with MD5 Algorythm and inserting in table.
When the string has a character 0, chr(0), the system give a message:

Unclosed quotation mark before the character string

Somebody help me?

Thanks for attenction!

Marcelo Allievi

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## MAK

Look BOL for

SET CONCAT_NULL_YIELDS_NULL { ON | OFF } 

but this set command makes you proc to recompile, so usually everbody uses isNULL()

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