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Oracle Escape Characters

Oracle Tips by Burleson Consulting


Oracle allows the assignment of special escape characters to tell Oracle that the character is interpreted literally.  Certain characters such as the underscore ?_? are not interpreted literally because they have special meaning within Oracle.

In the example below, we want to find all Oracle parameter that relate to I/O, so we are tempted to use the filter LIKE  ?%_io_%?.  Below we will select from the x$ksppi fixed table, filtering with the LIKE clause:

select ksppinm
from x$ksppi
where ksppinm like '%_io_%';















As you can see above, we did not get the answer we expected.  The SQL displayed all values that contained ?io?, and not just those with an underscore.  To remedy this problem, Oracle SQL supports an ESCAPE clause to tell Oracle that the character is to be interpreted literally:

select ksppinm
from x$ksppi
where ksppinm like '%\_io\_%' ESCAPE '\';



















This is an excerpt from the book Oracle 10g Grid & Real Application Clusters -
Oracle10g Grid Computing with RAC.



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