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:
- 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.
- 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 (
- Use Standard-Conforming Strings:
If you don’t want to use backslash as an escape character, you can turn on the
standard_conforming_stringsoption so that backslashes are treated as regular characters.
- UESCAPE Clause:
If you’re using Unicode escape sequences, ensure that the
UESCAPEclause is correct. The escape character must be a single character and must be followed by a plus sign (
+) and four hexadecimal digits.
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_stringsset to off and you want to insert a string with literal backslashes, you might encounter the
2200Berror 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.