How to diagnose and fix the 2200C invalid_use_of_escape_character error code in Postgres.

The 2200C error code in PostgreSQL indicates an “INVALID USE OF ESCAPE CHARACTER.” This error occurs when an escape character, such as a backslash (\), is used incorrectly within a string in a SQL query. To diagnose and fix this error, you should check the string literals and escape sequences in your query to ensure they are valid according to PostgreSQL syntax.

Here are some steps to diagnose and fix this error:

  1. Check String Literals: Look at the string literals in your query to see if there are any escape characters that are not used properly. In PostgreSQL, the backslash is used as an escape character within string literals.
  2. Use Double Backslashes: If you need to include a literal backslash in your string, you should use a double backslash (\\) to represent it.
  3. Standard Conforming Strings: PostgreSQL allows you to switch between using the standard conforming strings, where backslashes are just backslashes, and the traditional interpretation, where backslashes are escape characters. If you want to use backslashes as escape characters, you can turn on the traditional interpretation by setting the standard_conforming_strings parameter to off.

Here is an example of incorrect usage that might result in the 2200C error:

SELECT 'C:\Program Files\PostgreSQL';

In the above example, the backslashes are intended to be literal backslashes in a file path, but PostgreSQL interprets them as escape characters, which leads to an error.

To fix the error, you can use double backslashes:

SELECT 'C:\\Program Files\\PostgreSQL';

Alternatively, you can use the E string prefix to explicitly mark the string as containing escape sequences:

SELECT E'C:\\Program Files\\PostgreSQL';

If you are using a regular expression where a backslash is part of the pattern, you also need to double it:

SELECT '100\\d' ~ '100\\d{2}';

This query checks if the string ‘100\d’ matches the regular expression pattern ‘100\d{2}’, which means “100” followed by exactly two digits.

Remember to always check the context in which the error occurs, as the solution might vary depending on how the escape character is being used in your query.

For more information on error codes and escape sequences in PostgreSQL, you can refer to the official PostgreSQL documentation or relevant Stack Overflow discussions.

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