SQLite JSON1 example for JSON extract\set

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傲寒
傲寒 2020-12-23 12:40

SQLite has now an experimental JSON1 extension to work with JSON fields. The functions to choose from look promising, but I don\'t get how to use them in the context of a qu

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  • 2020-12-23 12:49

    So, here is a first example of how to use json_extract. First, the data is a inserted in a bit different way:

    insert into user (name, phone) values("oz", json('{"cell":"+491765", "home":"+498973"}'));
    

    Now, we can select all the users phone numbers as in normal sql:

    sqlite> select user.phone from user where user.name=='oz';
    {"cell":"+491765","home":"+498973"}
    sqlite> 
    

    But, what if we don't care about land lines and we want only cell phones?
    Enter json_extract:

    sqlite> select json_extract(user.phone, '$.cell') from user;
    +491765
    

    And this is how to use json_extract.

    Using json_set is similar. Given that the we want to update the cell phone:

    sqlite> select json_set(user.phone, '$.cell', 123) from \
            user;
    {"cell":123,"home":"+498973"}
    

    You can combine those function calls in other SQL queries. Thus, you can use SQLite with structured data and with unstructured data in the form of JSON.

    Here is how to update the user cell phone only:

    sqlite> update user 
       ...> set phone =(select json_set(user.phone, '$.cell', 721) from user)
       ...> where name == 'oz';
    sqlite> select * from user;
    oz|{"cell":721,"home":"+498973"}
    
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