返回重复记录

Question

我只想从表中返回重复记录.在我的情况下,如果多个记录在col1,col2,col3和col4中具有相同的值,则记录是重复的.

Answer 1

SELECT col1, col2, col3, col4
     , COUNT(*) AS cnt
FROM yourTable
GROUP BY col1, col2, col3, col4
HAVING COUNT(*) > 1

如果您希望显示其他列,则可以JOIN在上面添加到表中:

SELECT t.*
     , dup.cnt
FROM yourTable t
    JOIN
      ( SELECT col1, col2, col3, col4
             , COUNT(*) AS cnt
        FROM yourTable
        GROUP BY col1, col2, col3, col4
        HAVING COUNT(*) > 1
      ) AS dup
      ON  t.col1 = dup.col1
      AND t.col2 = dup.col2
      AND t.col3 = dup.col3
      AND t.col4 = dup.col4