如何获取 MySQL 列中数组的长度？

Question

我在 Temp 列中有一个数组，我正在尝试查找数组的长度。我尝试了 JSON_LENGTH 但它不起作用。

到目前为止我试过了

SELECT JSON_LENGTH(Temp)from tbl_name;

得到这个

Id  Temp
1   ['53682', '66890', '53925', '54847']
2   ['53682', '66890', '53925', '54843','54890']

预期输出：

Id  Temp                                             Count
1   ['53682', '66890', '53925', '54847']             4
2   ['53682', '66890', '53925', '54843','54890']     5

Answer 1

你有两种可能

老办法
将'替换为'

CREATE TABLE table1 (
  `Id` INTEGER,
  `Temp` VARCHAR(44)
);

INSERT INTO table1
  (`Id`, `Temp`)
VALUES
  ('1', "['53682', '66890', '53925', '54847']"),
  ('2', "['53682', '66890', '53925', '54843','54890']");

seLECT `Id`, `Temp`, CHAR_LENGTH (`Temp`) - CHAR_LENGTH (REPLACE(`Temp`,',','')) + 1  as cnt FROM table1

Id | Temp                                         | cnt
-: | :------------------------------------------- | --:
 1 | ['53682', '66890', '53925', '54847']         |   4
 2 | ['53682', '66890', '53925', '54843','54890'] |   5

CREATE TABLE table2 (
  `Id` INTEGER,
  `Temp` VARCHAR(44)
);

INSERT INTO table2
  (`Id`, `Temp`)
VALUES
  ('1', '["53682", "66890", "53925", "54847"]'),
  ('2', '["53682", "66890", "53925", "54843","54890"]');

SELECT `Id`, `Temp`, JSON_LENGTH(`Temp`) AS cnt FROM table2

Id | Temp                                         | cnt
-: | :------------------------------------------- | --:
 1 | ["53682", "66890", "53925", "54847"]         |   4
 2 | ["53682", "66890", "53925", "54843","54890"] |   5

db<>fiddle here

如何获取 MySQL 列中数组的长度？

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