TL;DR 使用时间戳文字来避免整个问题：

INSERT INTO MY_TABLE_NAME (
  UPDATED_DATE,
  CREATED_DATE,
  TEST_SUBJECT,
  THIRD_DATE
) VALUES (
  TIMESTAMP '2018-05-31 14:45:32.000',
  TIMESTAMP '2018-05-31 14:45:32.000',
  'test',
  TIMESTAMP '2018-06-09 14:45:00.000'
);

如果不能，请检查 NLS_NUMERIC_CHARACTERS 数据库/会话参数。如果小数点不是 . ，那么 x 格式模型将不匹配 . ，但将匹配数据库/会话使用的任何字符，并且字符串将不匹配。

SQL Fiddle

Oracle 11g R2架构设置

CREATE TABLE MY_TABLE_NAME (
  UPDATED_DATE TIMESTAMP,
  CREATED_DATE TIMESTAMP,
  TEST_SUBJECT VARCHAR2(20),
  THIRD_DATE   TIMESTAMP
);

查询1

-- Set decimal separator to "." and thousands separator to ","
ALTER SESSION SET NLS_NUMERIC_CHARACTERS = '.,'    
INSERT INTO MY_TABLE_NAME (
  UPDATED_DATE,
  CREATED_DATE,
  TEST_SUBJECT,
  THIRD_DATE
) VALUES (
  TO_TIMESTAMP('2018-05-31 14:45:32.000', 'YYYY-MM-DD HH24:MI:SSxFF'),
  TO_TIMESTAMP('2018-05-31 14:45:32.000', 'YYYY-MM-DD HH24:MI:SSxFF'),
  'test',
  TO_TIMESTAMP('2018-06-09 14:45:00.000', 'YYYY-MM-DD HH24:MI:SSxFF')
SELECT * FROM MY_TABLE_NAME

|          UPDATED_DATE |          CREATED_DATE | TEST_SUBJECT |            THIRD_DATE |
|-----------------------|-----------------------|--------------|-----------------------|
| 2018-05-31 14:45:32.0 | 2018-05-31 14:45:32.0 |         test | 2018-06-09 14:45:00.0 |

查询2

-- Set decimal separator to "," and thousands separator to " "
ALTER SESSION SET NLS_NUMERIC_CHARACTERS = ', '
INSERT INTO MY_TABLE_NAME (
  UPDATED_DATE,
  CREATED_DATE,
  TEST_SUBJECT,
  THIRD_DATE