Replace plan.ErrInsertIntoDuplicateColumn with sql.ErrColumnSpecifiedTwice, and add cast to MySqlError.

Author: nicktobey

server/handler_test.go

@@ -261,6 +261,14 @@ func TestHandlerErrors(t *testing.T) {
 			query:             "INSERT INTO `test`.`no_such_table` (`id`, `v`) VALUES (1, 2)",
 			expectedErrorCode: mysql.ERNoSuchTable,
 		},
+		{
+			name:              "insert into same column twice",
+			handler:           handler,
+			conn:              dummyConn,
+			setup:             []string{"CREATE TABLE `test_table` ( `id` INT NOT NULL PRIMARY KEY, `v` INT );"},
+			query:             "INSERT INTO `test`.`test_table` (`id`, `id`, `v`) VALUES (1, 2, 3)",
+			expectedErrorCode: mysql.ERFieldSpecifiedTwice,
+		},
 	}
 
 	for _, test := range tests {

sql/errors.go

@@ -885,6 +885,8 @@ var (
 	ErrInsertIntoMismatchValueCount = errors.NewKind("number of values does not match number of columns provided")
 
 	ErrInvalidTypeForLimit = errors.NewKind("invalid limit. expected %T, found %T")
+
+	ErrColumnSpecifiedTwice = errors.NewKind("column '%v' specified twice")
 )
 
 // CastSQLError returns a *mysql.SQLError with the error code and in some cases, also a SQL state, populated for the
@@ -953,6 +955,8 @@ func CastSQLError(err error) *mysql.SQLError {
 		code = mysql.ERTruncatedWrongValueForField
 	case ErrUnknownColumn.Is(err):
 		code = mysql.ERBadFieldError
+	case ErrColumnSpecifiedTwice.Is(err):
+		code = mysql.ERFieldSpecifiedTwice
 	case ErrLockDeadlock.Is(err):
 		// ER_LOCK_DEADLOCK signals that the transaction was rolled back
 		// due to a deadlock between concurrent transactions.

sql/plan/insert.go

@@ -30,7 +30,6 @@ var ErrReplaceIntoNotSupported = errors.NewKind("table doesn't support REPLACE I
 var ErrOnDuplicateKeyUpdateNotSupported = errors.NewKind("table doesn't support ON DUPLICATE KEY UPDATE")
 var ErrAutoIncrementNotSupported = errors.NewKind("table doesn't support AUTO_INCREMENT")
 var ErrInsertIntoUnsupportedValues = errors.NewKind("%T is unsupported for inserts")
-var ErrInsertIntoDuplicateColumn = errors.NewKind("duplicate column name %v")
 var ErrInsertIntoIncompatibleTypes = errors.NewKind("cannot convert type %s to %s")
 
 // cc: https://dev.mysql.com/doc/refman/8.0/en/sql-mode.html#sql-mode-strict

sql/planbuilder/dml_validate.go

@@ -111,7 +111,7 @@ func validateColumns(tableName string, columnNames []string, dstSchema sql.Schem
 		if _, exists := usedNames[columnName]; !exists {
 			usedNames[columnName] = struct{}{}
 		} else {
-			return plan.ErrInsertIntoDuplicateColumn.New(columnName)
+			return sql.ErrColumnSpecifiedTwice.New(columnName)
 		}
 	}
 	return nil