sql查询（两个表之间的输出结果不一样）

Question

我有2个表TableA和TableB，其属性为id, character

TableA
╔════╦═══════════╗
║ id ║ character ║
╠════╬═══════════╣
║  1 ║     A     ║
║  2 ║     B     ║
║  3 ║     C     ║
╚════╩═══════════╝

TableB
╔════╦═══════════╗
║ id ║ character ║
╠════╬═══════════╣
║  1 ║     A     ║
║  2 ║     B     ║
║  3 ║     D     ║
╚════╩═══════════╝

我想计算TableA和TableB之间字符列中有多少字符不匹配。

我不确定这是否正确：

SELECT COUNT(character) 
FROM TableA tba 
JOIN TableB tbb 
   ON tba.id = tbb.id 
WHERE tba.character NOT LIKE tbb.character 
GROUP BY character

Answer 1

您不需要group by语句：

SELECT COUNT(*)   
FROM TableA tba 
INNER JOIN TableB tbb 
   ON tba.id = tbb.id 
WHERE tba.character <> tbb.character