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How do I alter a MySQL table column defaults?
To alter a MySQL table column defaults, you can use the CHANGE command. The syntax is as follows −
alter table yourTableName change yourCoumnName youColumnName datatype not null default Value;
To understand the above syntax, let us create a table. The following is the query −
mysql> create table DefaultDemo −> ( −> ArrivalTime timestamp −> ); Query OK, 0 rows affected (0.65 sec)
Here is the query that describes the table with default column −
mysql> desc DefaultDemo;
The following is the output −
+-------------+-----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+-----------+------+-----+---------+-------+ | ArrivalTime | timestamp | YES | | NULL | | +-------------+-----------+------+-----+---------+-------+ 1 row in set (0.11 sec)
Now you can alter the MySQL table column for default value. The query is as follows −
mysql> ALTER TABLE DefaultDemo CHANGE ArrivalTime ArrivalTime TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP; Query OK, 0 rows affected (1.71 sec) Records: 0 Duplicates: 0 Warnings: 0
Check whether the default value got inserted or not with the help of insert command. The query is as follows −
mysql> insert into DefaultDemo values(); Query OK, 1 row affected (0.15 sec)
Display the records −
mysql> select *from DefaultDemo;
The following is the output −
+---------------------+ | ArrivalTime | +---------------------+ | 2018-12-07 11:31:00 | +---------------------+ 1 row in set (0.00 sec)
Updated on: 30-Jul-2019
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