Mysql 如何将子字符串_索引的结果强制转换为varchar？

mytable中的My csv列包含以下作为文本列的内容

我想创建一个视图，但希望生成的表是varchar列。但是，我得到的是以下选择文本：

CREATE VIEW my_view AS
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(csv, ';', 2), ';', -1) AS test
FROM mytable;

是否无法将这些字段转换为varchar或char

但是相反，我收到了短信

您是从哪里获取此信息的

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dbfiddle

我忘了提到csv字段是TEXT@membersound更新。

CREATE VIEW my_view AS
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(csv, ';', 2), ';', -1) AS test
FROM mytable;

CREATE TABLE mytable (csv VARCHAR(250))
SELECT 'john;doe;12;john@example.com' AS csv;

CREATE VIEW my_view AS
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(csv, ';', 2), ';', -1) AS test
FROM mytable;

CREATE TABLE test
SELECT * FROM my_view;

SHOW CREATE TABLE test;

Table | Create Table :---- | :------------------------------------------------------------------ test | CREATE TABLE `test` ( | `test` varchar(250) DEFAULT NULL | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

CREATE TABLE mytable (csv TEXT)
SELECT 'john;doe;12;john@example.com' AS csv;

CREATE VIEW my_view AS
SELECT CONVERT(SUBSTRING_INDEX(SUBSTRING_INDEX(csv, ';', 2), ';', -1), CHAR(255)) AS test
FROM mytable;

CREATE TABLE test
SELECT * FROM my_view;

SHOW CREATE TABLE test;

Table | Create Table :---- | :------------------------------------------------------------------ test | CREATE TABLE `test` ( | `test` varchar(255) DEFAULT NULL | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci