我如何计算和总结数据库中的值

Question

我有一个mysql中的表，它包含整数值，我的表是这样的。

我要总结的特定列的值，例如，我想计算总金额，总cashpaid和总平衡。我该怎么做？ MySQL的像这样的

Answer 1

使用SUM()功能：或者你可以

select SUM(amount) from tablename; 
select SUM(cashpaid) from tablename; 
select SUM(balance) from tablename; 

它们分成一个：

select SUM(amount), SUM(cashpaid), SUM(balance) from tablename; 

Answer 2

试试这个：

select SUM(amount) AS total_amount, SUM(cashpaid) AS total_cashpaid, SUM(balance) AS total_balance from tablename; 

Answer 3

如果你想要做

它在一个单一的查询中：

SELECT SUM(amount) as total_amount, SUM(cashpaid) as total_paid,SUM(balance) as total_balance FROM tablename; 

算元素使用COUNT（）

SELECT COUNT(*) FROM tablename; 

，最好使用此功能时使用别名的列名。

Answer 4

尝试

select sum(amount), sum(cashpaid), sum(balance) from tablename 

Answer 5

计数的记录总数使用count()功能。

，如：

select count(amount) from table_name; 

它将从上面的表格中你的问题3.

回报求和的SUM()在SELECT查询。 像：

select SUM(amount) as total_amount,SUM(cashpaid) as total_cash_paid,SUM(balance) as total_balance from table_name; 

as后，将查询执行后automaticaly创建新的列名。