For JSON string handling functions after MySQL5.7 support, the project uses two main functions:
1. JSON_EXTRACT (A, b) Note: a field value is parsed desired, b is a value of expression begins with $ '$ *' to remove all JSON string '$ .key' to remove a specific value '$ [n] .key ' is removed so that a value JSON array.
2. JSON_UNQUOTE (value) Note: This function is mainly used because of the functions in the extracted value "" as a character string, the function can be taken double quotes and converts to a string value.
Example: JSON string is
[{"form":"sj","name":"时间","type":"select","required":"true","value":"2020-02-14"},{"form":"remark","name":"备注","type":"text","required":"false","value":"上班"}}]
So we have to take the time necessary to json array so written 2020-02-14
SELECT JSON_UNQUOTE ( JSON_EXTRACT ( variant_value, '$[0].value' ) ) AS value FROM tablename
3. After an additional value extracted in the sql JSON string is not used as a filter condition where statement, if it is worth the need to show the different results may be queried set as the sub-tables, with a function to display a different case Found method exemplary case have to use the function:
(1)select case colum when '1' then '男' when '2' then '男' else '..' end from ......
(2)select case when colum = '1' then '男' when colum = '2' then '男' else '..' end from ......
These are used in the function point to JSON have handled the primary method recorded in the sql in what has been for inspection.
