OracleORA-00904

ORA-00904: Invalid Identifier

ORA-00904 is thrown when Oracle cannot resolve a column name or alias in the query. Oracle stores identifiers in uppercase unless they were created with double-quote delimiters.

Example Query

SELECT firstName FROM employees;
-- Fails if the column was created as FIRSTNAME (uppercase)

Common Causes

  1. 1Column name is lowercase but was created without double quotes (stored as uppercase)
  2. 2Typo in the column or alias name
  3. 3Referencing a SELECT alias in the WHERE clause (not allowed in Oracle)

How to Fix It

Check the column names with DESC table_name. Use uppercase identifiers to match Oracle's default storage. If the column was created with quotes, reference it as "firstName" (with double quotes, exact case).

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