Question

我有一个250列的表。我正在尝试选择所有列，但我想将DISTINCT用于两列。

我的开始就像那样：

SELECT *
FROM table_name
WHERE EXISTS (SELECT DISTINCT table_name.column_name FROM table_name).

但是不起作用。也许有人有任何想法？提前致谢。

Answer 1

假设ID是表的主键，

SELECT *
FROM   table_name t
WHERE NOT EXISTS (SELECT 1 FROM table_name WHERE col1 = t.col1 AND ID <> t.ID)
  AND NOT EXISTS (SELECT 1 FROM table_name WHERE col2 = t.col2 AND ID <> t.ID)

Answer 2

SELECT * 
FROM table_name t
WHERE NOT EXISTS (SELECT 1 
                  FROM table_name tt 
                  WHERE tt.col1 = t.col1 
                    AND tt.col2 = t.col2 
                    AND tt.id > t.id)

SQL：几个列的MS Access DISTINCT

2 个答案: