Why Does My Oracle Query Return ORA-00904: Invalid Identifier?

ORA-00904 Error: Invalid Identifier Resolution

When executing a simple query in Oracle, you may encounter the "ORA-00904: Invalid Identifier" error. This issue typically arises when values are incorrectly quoted.

Problem:

A user attempts to fetch values from a table using the following query:

select fname, lname 
  from reg1 
 where uname="bbb";

However, this query results in the error:

ORA-00904: "bbb": invalid identifier

Solution:

The error indicates that the value "bbb" is not recognized as a valid identifier. In Oracle, string values must be enclosed in single quotes. To resolve the issue, use the following modified query:

select fname,lname 
  from reg1 
 where uname='bbb';

Enclosing the value in single quotes will identify it as a string literal and prevent it from being treated as an invalid identifier. By making this minor adjustment, the query should execute successfully and return the requested values.

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