Question

我有一个关于国际象棋游戏的数据集，在获胜者栏中只有2个值：“ white”和“ black”。我想将COUNT（获胜者）显示为WHITE_WINS，将COUNT（获胜者）显示为BLACK_WINS。我尝试单独内部连接表，但是无法获得正确的SQL查询来完成工作。我如何获得像这样的表：

WHITE_WINS | BLACK_WINS
5986 ......................... 5893

Answer 1

使用条件聚合：

SELECT
    COUNT(CASE WHEN winner = 'white' THEN 1 END) AS WHITE_WINS,
    COUNT(CASE WHEN winner = 'black' THEN 1 END) AS BLACK_WINS
FROM yourTable;

Answer 2

使用sum()

select 
    sum(case when winner='white' then 1 else 0 end) as white,
    sum(case when winner='black' then 1 else 0 end) as black
from tableA

Answer 3

在1以下使用。

SELECT COUNT(CASE 
            WHEN winner = 'white'
                THEN 1
            ELSE 0
            END) AS WHITE_WINS
    ,COUNT(CASE 
            WHEN winner = 'black'
                THEN 1
            ELSE 0
            END) AS BLACK_WINS
FROM ChessTable;

如何在同一列的同一表中获得2个值的计数？

3 个答案: