Find centralized, trusted content and collaborate around the technologies you use most.
Teams
Q&A for work
Connect and share knowledge within a single location that is structured and easy to search.
我正在尝试对不存在的键进行选择计数查询,但我将计数值设为 1。我的查询是select count(*) from test_table where key = 'test'.
select count(*) from test_table where key = 'test'
但是没有称为测试的键。但是我的查询总是返回 1。知道为什么会这样吗?
单行是该计数的值 0。在 mysql 中它将返回一行,例如:count(*) 0