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Description

The ORA-30179 error in Oracle Database indicates that the format string used in a function like `DBMS_OUTPUT.PUT_LINE` contains an invalid argument index. This commonly occurs when the index is zero, negative, or improperly formatted within the format string.

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Error Message

ORA-30179: invalid argument index used in a format code

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Known Causes

3 known causes

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Zero or Negative Index

The format string contains an argument index that is zero or negative, which is not permitted.

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Incorrect Formatting

The argument index within the format string is not properly enclosed within parentheses or is missing the opening parenthesis.

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Missing Argument

The format string specifies an argument index that exceeds the number of arguments provided to the formatting function.

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Solutions

3 solutions available

1. Correcting Argument Index in `TO_CHAR` or `TO_DATE` Functions easy

Identify and fix incorrect argument indices within `TO_CHAR` or `TO_DATE` format strings.

1

Locate the SQL statement or PL/SQL code that is causing the ORA-30179 error. This often involves functions like `TO_CHAR` or `TO_DATE`.

2

Examine the format string used in the `TO_CHAR` or `TO_DATE` function. The error indicates an 'argument index' issue. This typically means you're trying to reference a placeholder in the format mask that doesn't correspond to an actual argument provided, or the index is out of bounds.

Example of a potentially problematic `TO_CHAR` call:

SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS.FF3') FROM dual;

If you were to try something like `TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS.FF3, AM')` where 'AM' is not a valid format element for an argument index, it might lead to this error.

3

Ensure that any numbered format elements (e.g., `FX`, `FM` can sometimes be used in conjunction with specific argument referencing, though less common for direct index errors) or positional placeholders are correctly aligned with the arguments passed to the function. For standard `TO_CHAR` and `TO_DATE`, the format mask itself defines the output and doesn't typically use explicit argument indices like `%1$s` in some other languages. The error is more likely due to an invalid character or sequence within the format mask that Oracle interprets as an attempt to reference a non-existent argument.

Correct usage example:

SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS.FF3') FROM dual;
SELECT TO_DATE('2023-10-27 10:30:00', 'YYYY-MM-DD HH24:MI:SS') FROM dual;

4

If you are using `TO_CHAR` with the `NLSL` parameters and attempting to reference specific arguments from a list (which is rare for ORA-30179), ensure those argument indices are valid and within the range of the provided arguments.

2. Validating Format Mask Syntax easy

Verify that the format mask used in date/time functions adheres to Oracle's syntax rules.

1

Review the Oracle documentation for the `TO_CHAR` and `TO_DATE` functions to confirm the correct syntax for the format elements you are using.

Refer to the Oracle documentation for your specific database version. For example, search for 'Oracle TO_CHAR format elements' or 'Oracle TO_DATE format elements'.

2

Pay close attention to elements like `FF` (fractional seconds) and ensure they are used correctly. For instance, `FF` followed by a number indicates the precision of fractional seconds. An incorrect number or misplaced character here can cause the error.

Correct usage of fractional seconds:

SELECT TO_CHAR(SYSTIMESTAMP, 'YYYY-MM-DD HH24:MI:SS.FF9') FROM dual;
-- This formats the timestamp with nanosecond precision.

3

Check for any unintended characters or typos within the format mask. Sometimes, a simple mistyped character can be misinterpreted by Oracle as an invalid format element or an attempt to use an invalid argument index.

Incorrect format example:

SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS.FFF') FROM dual; -- 'FFF' is not a valid format element for fractional seconds; it should be FF followed by a number like FF3, FF6, FF9.

Corrected example:

SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS.FF3') FROM dual;

3. Investigating Underlying Data and Context medium

Examine the data being processed and the context in which the error occurs to find the root cause.

1

If the error occurs during batch processing or when querying a large dataset, try to isolate the specific row or set of rows that trigger the error. This can often be done by adding `ROWNUM` clauses or filtering based on known problematic values.

Example of isolating problematic data:

SELECT * FROM your_table WHERE ROWNUM <= 100 AND TO_CHAR(your_date_column, 'YYYY-MM-DD') = 'some_problematic_date';

Or, if you suspect a specific value:

SELECT * FROM your_table WHERE your_column_causing_error LIKE '%some_pattern%';

2

If the error is related to `TO_DATE` and the input string format, ensure the input string consistently matches the specified format mask. Inconsistent data can lead to parsing errors that might manifest as ORA-30179 if the parser gets confused.

Example of inconsistent data:

-- Assume format mask is 'YYYY-MM-DD HH24:MI:SS'
-- Input string: '2023-10-27 10:30:00' (Correct)
-- Input string: '27-10-2023 10:30:00' (Incorrect, will cause parsing issues)

If your code attempts to convert '27-10-2023 10:30:00' using 'YYYY-MM-DD HH24:MI:SS', it will fail. While this might not directly cause ORA-30179, a malformed input that the formatter tries to interpret as an argument index could.

3

Consider if any dynamic SQL or PL/SQL code is constructing the format string. Errors in string concatenation or variable substitution could lead to an invalid format mask being generated.

Example of dynamic SQL issue:

DECLARE
  v_format_mask VARCHAR2(100) := 'YYYY-MM-DD '; -- Missing time components
  v_date DATE := SYSDATE;
BEGIN
  -- This might lead to an error if the full format is expected later or if v_format_mask is used incorrectly
  DBMS_OUTPUT.PUT_LINE(TO_CHAR(v_date, v_format_mask || ' HH24:MI:SS'));
END;
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Oracle ORA-30179: Invalid Format Index