Se o
URL parte existe apenas uma vez no texto, o seguinte deve estar funcionando. MySQL Solução:
select concat( @pss:=substring_index( txt, 'http://', 1 ),
substring( @ss:=substring_index( txt, 'http://', -1 ),
if( (@l:=locate( ' ', @ss )) > 0, @l+1, 0 ) )
) as txt
from (
select 'This is a test http://t.co/aBc689XYz' as txt
union all
select 'Have a nice http://t.co/vZ754PlkuI day'
union all
select 'This worked http://sqlfiddle.com/#!2/d41d8 perfectly on sql fiddle'
) records
;
Resultados :
+-------------------------------------+
| txt |
+-------------------------------------+
| This is a test |
| Have a nice day |
| This worked perfectly on sql fiddle |
+-------------------------------------+
Demonstração @ MySQL 5.5.32 Fiddle
