How to diagnose and fix the 2200B escape_character_conflict error code in Postgres.

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The 2200B error code in PostgreSQL is specifically related to an escape character conflict. This error occurs when an escape string (E’…’) contains an invalid escape sequence. Here’s how to diagnose and fix this error:

  1. Review the Error Message:
    Look at the detailed error message provided by PostgreSQL. It will often tell you which part of the string is causing the conflict.
  2. Check Escape Sequences:
    In PostgreSQL, escape sequences in strings are introduced by a backslash (\). Ensure that any backslashes in your string literals are intended to be escape characters, and if they are meant to be literal backslashes, they should be doubled (\\).
  3. Use Standard-Conforming Strings:
    If you don’t want to use backslash as an escape character, you can turn on the standard_conforming_strings option so that backslashes are treated as regular characters.
  4. UESCAPE Clause:
    If you’re using Unicode escape sequences, ensure that the UESCAPE clause is correct. The escape character must be a single character and must be followed by a plus sign (+) and four hexadecimal digits.

Examples

Here are some examples of how you might encounter the 2200B error code and what you could do to fix it:

  • Example 1: Invalid Escape Sequence
  SELECT E'This is an invalid escape sequence: \x';

This query will result in an 2200B error because \x is not a valid escape sequence. To fix this, you would need to correct the escape sequence or double the backslash if it’s meant to be a literal backslash:

  SELECT E'This is a valid escape sequence: \\x';
  • Example 2: Incorrect UESCAPE Usage
  SELECT U&'d!000061ta' UESCAPE '!';

This is a correct usage of the UESCAPE clause, where ! is the escape character. If an invalid character was used in the UESCAPE clause, such as a letter or a number, it would result in a 2200B error. The escape character must be a single character that is not a hexadecimal digit or a plus sign.

  • Example 3: Literal Backslashes with standard_conforming_strings
    If you have standard_conforming_strings set to off and you want to insert a string with literal backslashes, you might encounter the 2200B error if you don’t escape them properly. For example:
  INSERT INTO my_table (my_column) VALUES (E'C:\\Program Files\\MyApp');

If you have standard_conforming_strings set to on, you can use single backslashes:

  SET standard_conforming_strings = on;
  INSERT INTO my_table (my_column) VALUES ('C:\Program Files\MyApp');

In each case, understanding the role of escape characters and how they should be used in PostgreSQL is key to resolving the 2200B error. If you are still having trouble, consulting the PostgreSQL documentation on error codes or the PostgreSQL documentation on lexical structure may provide additional insights.

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