如何替换MYSQL中列的某个值？

Question

how to replace a certain value of a column. for example I have three rows of values ​​in a table:

id_tweet: 1
status_user: RT @username1: success rta: P

id_tweet: 2
status_user: RT @username2: happy rta: D

id_tweet: 3
status_user: amen

of the three records above I want to replace or remove retweet text in the status_user column to:

after replace:

id_tweet: 1
status_user: success rta: P

id_tweet: 2
status_user: happy rtx: D

id_tweet: 3
status_user: amen

but I have constraints. I think I can use the replace function query on mysql as follows:

UPDATE tes_tbl_status
SET status_user = (SELECT REPLACE (status_user, '?', '') FROM 
tes_tbl_status WHERE status_user LIKE 'RT%:%')
WHERE status_user LIKE 'RT%:%';

information : '?' = RT @...:

query above by replacing a certain value in the status_user column with an empty string value, however I do not yet know how to retrieve the text value

RT @ ...:

which will be replaced with an empty string. anyone have any idea or solution for my problem?

Answer 1

If you want to remove always the RT @...: parts, the SUBSTRING_INDEX , CONCAT and REPLACE mysql functions are there for your help. Using SUBSTRING_INDEX you can extract the RT @... substring that you can CONCAT with a colon ( : ) and apply this result in the REPLACE function as the from_str parameter to be replaced by an empty string.

Here is the code what do the update for you:

UPDATE t
SET status_user = TRIM(REPLACE(status_user, CONCAT(SUBSTRING_INDEX(status_user, ':', 1),':'), ''))
WHERE status_user LIKE 'RT%';

Result :

+----------+----------------+
| id_tweet | status_user    |
+----------+----------------+
|        1 | success rta: P |
|        2 | happy rta: D   |
|        3 | amen           |
+----------+----------------+

Note the TRIM that i used to remove the leading and trailing spaces (if exist).

See sqlfiddle demo here .

DDL :

CREATE TABLE t (
  id_tweet INT UNSIGNED NOT NULL,
  status_user TEXT NOT NULL
);

INSERT INTO t (id_tweet, status_user) VALUES
(1, 'RT @username1: success rta: P'),
(2, 'RT @username2: happy rta: D'),
(3, 'amen');

Also there is a nice mysql udf library ( lib_mysqludf_preg ) that can equips your mysql with PCRE pattern matching functionalities.