SQL:选择列中每个值的总和 [英] SQL: Select sum of each individual value of a column

问题描述

有一列可以包含多个值.我想选择一个计数，每个离散值在整个集合中出现多少次.我觉得可能有一个明显的解决方案，但这使我望而却步.我将显示输入&预期的输出，希望它足够明显，您将了解.

There is a column that can have several values. I want to select a count of how many times each distinct value occurs in the entire set. I feel like there's probably an obvious solution but it's eluding me. I'll show input & expected output, hopefully it's obvious enough that you'll understand.

这是示例数据:

|-------|
| class |
|-------|
| 5     |
| 5     |
| 12    |
| 4     |
| 12    |
|-------|

这是我想要获得的输出:

This is the output I'm trying to get:

|-------|-------|
| class | count |
|-------|-------|
| 5     | 2     |
| 12    | 2     |
| 4     | 1     |
|-------|-------|

推荐答案

SELECT CLASS, COUNT (*)
FROM MYTABLE
GROUP BY CLASS

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