Stored Procedure error ORA-06550

Learn stored procedure error ora-06550 with practical examples, diagrams, and best practices. Covers sql, oracle-database, stored-procedures development techniques with visual explanations.

Troubleshooting ORA-06550: PL/SQL Compilation Errors in Oracle Stored Procedures

Hero image for Stored Procedure error ORA-06550

Learn to diagnose and resolve the common ORA-06550 error, which indicates a PL/SQL compilation issue in Oracle stored procedures, functions, or packages. This guide covers common causes and effective debugging strategies.

The ORA-06550 error is a frequent encounter for developers working with Oracle PL/SQL. It signifies a compilation error within a stored procedure, function, package, or anonymous PL/SQL block. Unlike runtime errors, ORA-06550 means that Oracle could not successfully parse and compile your code, preventing it from being executed. Understanding the underlying causes and systematic debugging approaches is crucial for efficient development in an Oracle environment.

Understanding ORA-06550 and Its Common Causes

The ORA-06550 error message itself is often a wrapper for a more specific syntax or semantic error. It typically appears with additional lines indicating the exact location (line number and column) and the nature of the problem. This makes it a powerful diagnostic tool, provided you know how to interpret the accompanying details.

Common reasons for ORA-06550 include:

  • Syntax Errors: Missing semicolons, incorrect keywords, mismatched parentheses, or improper use of operators.
  • Undeclared Identifiers: Referencing variables, procedures, functions, or tables that do not exist or are out of scope.
  • Incorrect Data Types: Attempting to assign a value of one data type to a variable of an incompatible type.
  • Missing or Invalid Parameters: Calling a procedure or function with an incorrect number or type of arguments.
  • Privilege Issues: Lacking the necessary EXECUTE privileges on referenced objects or CREATE PROCEDURE privileges.
  • Reserved Keywords: Using Oracle reserved words as identifiers.
  • Invalid SQL Statements: Embedding an SQL statement within PL/SQL that has its own syntax errors.
flowchart TD
    A[PL/SQL Code Submission] --> B{Oracle Parser}
    B -->|Syntax Errors| C[ORA-06550: Line/Column X, Y]
    B -->|Semantic Errors| C
    C --> D{Developer Debugging}
    D -->|Fix Code| A
    B -->|No Errors| E[Compilation Successful]
    E --> F[Stored Procedure Created/Altered]

Flowchart illustrating the PL/SQL compilation process and ORA-06550 trigger points.

Diagnosing and Resolving ORA-06550 Errors

The key to resolving ORA-06550 is to meticulously examine the error details provided by Oracle. The line and column numbers are your best friends. Here's a systematic approach:

  1. Locate the Error: Pay close attention to the line and column numbers in the error message. This pinpoints the exact location of the syntax or semantic issue.
  2. Check for Syntax: Review the code around the indicated line. Look for common syntax mistakes like missing END; statements, unclosed quotes, or misplaced commas.
  3. Verify Object Existence and Spelling: Ensure all referenced tables, views, procedures, functions, and variables are spelled correctly and exist in the schema you are working with, or are properly qualified (e.g., SCHEMA.TABLE_NAME).
  4. Examine Data Types: Confirm that data types are compatible during assignments or parameter passing. Implicit conversions can sometimes mask issues, but explicit mismatches will cause errors.
  5. Review Parameters: If the error occurs during a procedure or function call, check that the number, order, and data types of the arguments match the definition of the called routine.
  6. Check Privileges: Ensure the user compiling the code has the necessary SELECT, INSERT, UPDATE, DELETE, or EXECUTE privileges on all referenced objects.
  7. Consult USER_ERRORS: For more complex procedures or packages, the USER_ERRORS data dictionary view provides a comprehensive list of compilation errors. This is especially useful when compiling larger blocks of code where the initial ORA-06550 might be too generic.
CREATE OR REPLACE PROCEDURE my_bad_procedure
IS
    v_name VARCHAR2(100);
BEGIN
    -- Missing semicolon here will cause ORA-06550
    SELECT first_name INTO v_name FROM employees WHERE employee_id = 100
    DBMS_OUTPUT.PUT_LINE('Employee Name: ' || v_name);
END my_bad_procedure;

Example of a PL/SQL procedure with a missing semicolon, leading to ORA-06550.

Using SHOW ERRORS and USER_ERRORS for Detailed Diagnostics

When you encounter ORA-06550, the most effective way to get detailed error messages is by using the SHOW ERRORS command in SQL*Plus or SQL Developer, or by querying the USER_ERRORS data dictionary view. These tools provide the specific PL/SQL error messages that are masked by the generic ORA-06550.

SHOW ERRORS is a quick way to see compilation errors for the last compiled object in your session. For example, after attempting to CREATE OR REPLACE PROCEDURE, you would simply type SHOW ERRORS.

For more persistent or programmatic access to errors, USER_ERRORS is invaluable. It stores all compilation errors for objects owned by the current user. You can filter by object type and name to find errors for a specific procedure, function, or package.

-- After attempting to compile a procedure or package:
SHOW ERRORS;

-- To query specific errors from USER_ERRORS:
SELECT line, position, text
FROM user_errors
WHERE name = 'MY_BAD_PROCEDURE'
  AND type = 'PROCEDURE'
ORDER BY line, position;

Using SHOW ERRORS and USER_ERRORS to retrieve detailed PL/SQL compilation errors.