SQLite 中的 SELECT *, COUNT(*) [英] SELECT *, COUNT(*) in SQLite

问题描述

如果我在 SQLite 中执行标准查询:

If i perform a standard query in SQLite:

SELECT * FROM my_table

我按预期获得了表中的所有记录.如果我执行以下查询:

I get all records in my table as expected. If i perform following query:

SELECT *, 1 FROM my_table

我按预期获得所有记录，所有记录中最右侧的列都为1".但是如果我执行查询:

I get all records as expected with rightmost column holding '1' in all records. But if i perform the query:

SELECT *, COUNT(*) FROM my_table

我只得到一行(最右边的列是正确的计数).为什么是这样的结果?我不太擅长 SQL，可能会出现这种行为?这对我来说似乎很奇怪和不合逻辑:(.

I get only ONE row (with rightmost column is a correct count). Why is such results? I'm not very good in SQL, maybe such behavior is expected? It seems very strange and unlogical to me :(.

推荐答案

SELECT *, COUNT(*) FROM my_table 不是你想要的，它不是真正有效的 SQL，你必须分组由非聚合的所有列组成.

SELECT *, COUNT(*) FROM my_table is not what you want, and it's not really valid SQL, you have to group by all the columns that's not an aggregate.

你会想要类似的东西

SELECT somecolumn,someothercolumn, COUNT(*) 
   FROM my_table 
GROUP BY somecolumn,someothercolumn

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