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Set default value to a JSON type column in MySQL?
To set default value, use the DEFAULT constraint as in the below syntax −
alter table yourTableName modify column yourColumnName JSON NOT NULL DEFAULT ( JSON_OBJECT() );
Let us create a table −
mysql> create table demo24 −> ( −> employee_information text −> ) −> ; Query OK, 0 rows affected (1.43 sec)
Here is the description of table. Following is the query −
mysql> desc demo24;
This will produce the following output −
+----------------------+------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------------+------+------+-----+---------+-------+ | employee_information | text | YES | | NULL | | +----------------------+------+------+-----+---------+-------+ 1 row in set (0.00 sec)
Following is the query to change it to JSON data type with default value −
mysql> alter table demo24 modify column employee_information JSON NOT NULL DEFAULT ( JSON_OBJECT() ); Query OK, 0 rows affected (3.03 sec) Records: 0 Duplicates: 0 Warnings: 0
Now check the description of table. Following is the query −
mysql> desc demo24;
This will produce the following output −
+----------------------+------+------+-----+---------------+-------------------+ | Field | Type | Null | Key | Default | Extra | +----------------------+------+------+-----+---------------+-------------------+ | employee_information | json | NO | | json_object() | DEFAULT_GENERATED | +----------------------+------+------+-----+---------------+-------------------+ 1 row in set (0.00 sec)
Insert some records into the table with the help of insert command −
mysql> insert into demo24 values();; Query OK, 1 row affected (0.10 sec)
Display records from the table using select statement −
mysql> select *from demo24;
This will produce the following output −
+----------------------+
| employee_information |
+----------------------+
| {} |
+----------------------+
1 row in set (0.00 sec)
Updated on: 19-Nov-2020
1K+ Views
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