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How to create and fill a new column in an already created MySQL table?
Let us first create a table −
mysql> create table DemoTable -> ( -> Value1 int, -> Value2 int -> ); Query OK, 0 rows affected (0.77 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values(10,10); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(20,30); Query OK, 1 row affected (0.24 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable;
Output
This will produce the following output −
+--------+--------+ | Value1 | Value2 | +--------+--------+ | 10 | 10 | | 20 | 30 | +--------+--------+ 2 rows in set (0.00 sec)
Following is the query to create and fill a new third column in a MySQL table. Here, boolean is considered as an integer in an integer context, i.e. the values 0 for false and 1 for true.
We have used generated column here −
mysql> alter table DemoTable add Value3 int generated always as (Value1 = Value2); Query OK, 0 rows affected (0.51 sec) Records: 0 Duplicates: 0 Warnings: 0
Let us display all records from the table once again −
mysql> select *from DemoTable;
Output
This will produce the following output −
+--------+--------+--------+ | Value1 | Value2 | Value3 | +--------+--------+--------+ | 10 | 10 | 1 | | 20 | 30 | 0 | +--------+--------+--------+ 2 rows in set (0.00 sec)
Updated on: 30-Jun-2020
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