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How to add subtotal to a table column displaying NULL in MySQL?
Let us first create a table −
mysql> create table DemoTable -> ( -> Amount int, -> SubTotal int -> ); Query OK, 0 rows affected (0.65 sec)
Insert some records in the table using insert command −
ysql> insert into DemoTable(Amount) values(50); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Amount) values(60); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(Amount) values(70); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(Amount) values(80); Query OK, 1 row affected (0.17 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable;
Output
This will produce the following output −
+--------+----------+ | Amount | SubTotal | +--------+----------+ | 50 | NULL | | 60 | NULL | | 70 | NULL | | 80 | NULL | +--------+----------+ 4 rows in set (0.00 sec)
Here is the query to add subtotal to a column in MySQL.
mysql> set @sum := 0; Query OK, 0 rows affected (0.10 sec) mysql> update DemoTable set SubTotal = (@sum := @sum + Amount); Query OK, 4 rows affected (0.19 sec) Rows matched: 4 Changed: 4 Warnings: 0
Let us check the table records once again −
mysql> select *from DemoTable;
Output
This will produce the following output −
+--------+----------+ | Amount | SubTotal | +--------+----------+ | 50 | 50 | | 60 | 110 | | 70 | 180 | | 80 | 260 | +--------+----------+ 4 rows in set (0.00 sec)
Updated on: 30-Jun-2020
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