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Description

Error P0002, 'no data found', is a PL/pgSQL specific error. It occurs when a query within a PL/pgSQL block, typically a `SELECT INTO` statement, expects to retrieve exactly one row but finds zero rows matching the specified criteria.

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Error Message

no data found

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Known Causes

3 known causes

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Expected Single Row Not Found

A `SELECT INTO` statement or similar PL/pgSQL construct was designed to retrieve exactly one row, but the query returned no matching data.

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Incorrect Query Conditions

The `WHERE` clause or other filtering conditions in your query are too restrictive, contain typos, or do not match any existing data.

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Missing or Deleted Data

The specific data targeted by your query does not exist in the database, or it has been unexpectedly deleted.

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Solutions

4 solutions available

1. Verify Query Logic and Table Contents easy

Check your SQL query and the data within your PostgreSQL tables.

1

Examine the `WHERE` clause of your `SELECT` statement. Ensure the conditions accurately reflect the data you expect to retrieve. For example, if you're filtering by an ID, double-check that the ID exists in the table.

SELECT * FROM your_table WHERE your_column = 'expected_value';

2

Manually query the table with more general `WHERE` clauses or without any `WHERE` clause to see if any rows are returned at all. This helps determine if the issue is with your specific filter or with the table's content.

SELECT * FROM your_table;
-- Or with a broader filter:
SELECT * FROM your_table WHERE your_column LIKE '%partial_value%';

3

If you are expecting specific data, try querying for a known existing record to confirm table accessibility and basic query syntax.

SELECT * FROM your_table WHERE primary_key_column = 123; -- Replace with a known primary key

2. Check for Typos in Table and Column Names easy

Ensure that the table and column names in your query are spelled correctly.

1

Carefully review your `SELECT`, `FROM`, and `WHERE` clauses for any spelling mistakes in table names, column names, or aliases.

-- Incorrect spelling example:
SELECT user_id, user_name FROM usrrs WHERE status = 'active';
-- Correct spelling:
SELECT user_id, user_name FROM users WHERE status = 'active';

2

Use a PostgreSQL client tool (like `psql`, pgAdmin, DBeaver) to inspect the database schema and verify the exact spelling of table and column names.

-- In psql:
\d your_table_name

3. Investigate Data Type Mismatches and Case Sensitivity medium

Ensure data types align and consider case sensitivity in string comparisons.

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If you are comparing values in your `WHERE` clause, make sure the data types are compatible. For instance, comparing a string to a number might not yield results if not handled correctly.

-- If 'user_id' is an integer and you're comparing it to a string:
SELECT * FROM users WHERE user_id = '123'; -- Potentially problematic
-- Correct way:
SELECT * FROM users WHERE user_id = 123;

2

Be aware of PostgreSQL's case sensitivity for string comparisons. By default, `=` is case-sensitive. Use `ILIKE` for case-insensitive matching if needed.

-- Case-sensitive comparison (default):
SELECT * FROM products WHERE name = 'Apple'; -- Will NOT match 'apple'
-- Case-insensitive comparison:
SELECT * FROM products WHERE name ILIKE 'Apple';

3

If you're dealing with date or timestamp comparisons, ensure the format of your literal strings matches PostgreSQL's expected format or use explicit casting.

-- Potentially problematic:
SELECT * FROM events WHERE event_date = '2023-10-27';
-- Using explicit casting (often safer):
SELECT * FROM events WHERE event_date = CAST('2023-10-27' AS DATE);

4. Review Application Code or ORM Usage medium

If the query is generated by an application, examine the code producing the SQL.

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If your application uses an Object-Relational Mapper (ORM) like SQLAlchemy, Hibernate, or an ORM within a framework (e.g., Django ORM, Rails ActiveRecord), inspect the generated SQL. Most ORMs provide a way to log or view the executed SQL.

-- Example: In Django, you might enable logging or use print(queryset.query)

2

Check the logic in your application code that constructs the query. There might be conditional logic that leads to an empty `WHERE` clause or incorrect parameter values being passed to the database.

def get_user_by_id(user_id):
  # If user_id is None or invalid, this query might return no rows
  return User.objects.filter(id=user_id).first()

3

Verify that the data being passed from your application to the database for filtering or insertion is correct and matches expected formats and types.

const userId = null; // or an incorrect value
const query = `SELECT * FROM users WHERE id = ${userId}`; // This will likely yield no results

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Related Errors

5 related errors

PostgreSQL Error P0002: Query Returned No Rows