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我正在尝试设置0到任何空值在LEFT JOIN,使用COALESCE()或IFNULL(),SQLite中。 我知道这个问题已经被问了很多,但是,我坚持。当我LEFT JOIN表2,我怎么返回0,如果该值为NULL?
BUDGET
amount category
2 food
2 book
2 movie
EXPENSE
amount category
2 food
2 book
EXPECTED RESULT
budsum budcat expsum
2 food 2
2 book 2
2 movie 0
这是我所做的查询。
SELECT SUM(budget.amount) AS budsum, budget.category AS budcat,
SUM(coalesce(expense.amount,0)) AS expsum
FROM budget
LEFT JOIN expense
ON budcat=expense.category
GROUP BY budcat;
SELECT SUM(budget.amount) AS budsum, budget.category AS budcat,
SUM(coalesce(expense.amount,0)) AS expsum
FROM budget
LEFT JOIN expense
ON budcat=expense.category
GROUP BY budcat;
了我在尝试过。没有工作。对于某些上下文,我正在编写Ionic2应用程序,使用Cordova-sqlite-storage作为数据库 –
@AhmadZul - 没有工作如何?它还产生了空值?它失败了吗? – GurV
它没有失败。只是没有返回0值 –