How to fix 2200C: invalid_use_of_escape_character in PostgreSQL

Determine if you actually need escape characters. For literal backslashes or ampersands, you may not need escape sequences.

Example for literal backslash:
SELECT 'C:\\\\Users\\\\name';

Example for literal ampersand:
SELECT 'AT&T';

If you need backslash escapes, use E prefix:

Wrong:
SELECT 'line1\\\\nline2';

Correct:
SELECT E'line1\\\\nline2';

Valid escape sequences include: \\\\b, \\\\f, \\\\n, \\\\r, \\\\t, \\\\o, \\\\x, \\\\u, \\\\U

For Unicode escapes, ensure proper syntax:

4-digit hex:
SELECT U&'d\\\\0061t\\\\0061';

6-digit with + sign:
SELECT U&'d\\\\+000061t\\\\+000061';

Custom escape:
SELECT U&'d!0061t!+000061' UESCAPE '!';

Check the setting:
SHOW standard_conforming_strings;

If 'on', use E prefix. For old code migration:

Option 1: Update queries
SELECT E'line1\\\\nline2';

Option 2: Temporary change (not for production)
SET standard_conforming_strings = off;
-- Run query
SET standard_conforming_strings = on;

For complex strings, use dollar-quoting:

Instead of:
SELECT E'Complex string with quotes';

Use:
SELECT $$
Complex string with quotes
$$;

Or with custom tag:
SELECT $mytag$
Complex string
$mytag$;

Test queries after changes:

Test backslash escapes:
SELECT E'Test\\\\nNew\\\\tLine';

Test Unicode:
SELECT U&'Hello \\\\0061\\\\0062\\\\0063';

Use parameterized queries in application code.