如何使用Oracle query获取字符串长度

SELECT LENGTH('Hello, World!') AS string_length FROM DUAL;

CREATE TABLE example_table (
  id NUMBER,
  text_column VARCHAR2(255)
);

INSERT INTO example_table (id, text_column) VALUES (1, 'Hello, World!');
INSERT INTO example_table (id, text_column) VALUES (2, 'Oracle is awesome!');

SELECT id, LENGTH(text_column) AS string_length FROM example_table;

SELECT id, CHAR_LENGTH(text_column) AS char_string_length FROM example_table;