Add pqerror package

CHANGELOG.md

@@ -8,6 +8,22 @@ unreleased
 
 - Support `sslmode=prefer` and `sslmode=allow` ([#1270]).
 
+- Add a new `pqerror` package with PostgreSQL error codes ([#1275]).
+
+  For example, to test if an error is a UNIQUE constraint violation:
+
+      pqErr, ok := pq.AsType[*pq.Error](err)
+      if ok && pqErr.Code == pqerror.UniqueViolation {
+          log.Fatalf("email %q already exsts", email)
+      }
+
+  To make this a bit more convenient, it also adds a pqerror.As() function:
+
+      pqErr := pqerror.As(err, pqerror.UniqueViolation)
+      if pqErr != nil {
+          log.Fatalf("email %q already exsts", email)
+      }
+
 ### Fixes
 
 - Fix SSL key permission check to allow modes stricter than 0600/0640#1265 ([#1265]).
@@ -23,6 +39,7 @@ unreleased
 [#1267]: https://github.com/lib/pq/pull/1267
 [#1270]: https://github.com/lib/pq/pull/1270
 [#1272]: https://github.com/lib/pq/pull/1272
+[#1275]: https://github.com/lib/pq/pull/1275
 
 v1.11.2 (2026-02-10)
 --------------------
@@ -134,6 +151,8 @@ newer. Previously PostgreSQL 8.4 and newer were supported.
 
 - Handle ErrorResponse in readReadyForQuery and return proper error ([#1136]).
 
+- Detect COPY even if the query starts with whitespace or comments ([#1198]).
+
 - CopyIn() and CopyInSchema() now work if the list of columns is empty, in which
   case it will copy all columns ([#1239]).
 
@@ -159,6 +178,7 @@ newer. Previously PostgreSQL 8.4 and newer were supported.
 [#1180]: https://github.com/lib/pq/pull/1180
 [#1184]: https://github.com/lib/pq/pull/1184
 [#1188]: https://github.com/lib/pq/pull/1188
+[#1198]: https://github.com/lib/pq/pull/1198
 [#1211]: https://github.com/lib/pq/pull/1211
 [#1212]: https://github.com/lib/pq/pull/1212
 [#1214]: https://github.com/lib/pq/pull/1214

deprecated.go

@@ -11,49 +11,6 @@ type PGError interface {
 	Get(k byte) (v string)
 }
 
-// Get implements the legacy PGError interface.
-//
-// Deprecated: new code should use the fields of the Error struct directly.
-func (e *Error) Get(k byte) (v string) {
-	switch k {
-	case 'S':
-		return e.Severity
-	case 'C':
-		return string(e.Code)
-	case 'M':
-		return e.Message
-	case 'D':
-		return e.Detail
-	case 'H':
-		return e.Hint
-	case 'P':
-		return e.Position
-	case 'p':
-		return e.InternalPosition
-	case 'q':
-		return e.InternalQuery
-	case 'W':
-		return e.Where
-	case 's':
-		return e.Schema
-	case 't':
-		return e.Table
-	case 'c':
-		return e.Column
-	case 'd':
-		return e.DataTypeName
-	case 'n':
-		return e.Constraint
-	case 'F':
-		return e.File
-	case 'L':
-		return e.Line
-	case 'R':
-		return e.Routine
-	}
-	return ""
-}
-
 // ParseURL converts a url to a connection string for driver.Open.
 //
 // Deprecated: directly passing an URL to sql.Open("postgres", "postgres://...")