I'd like to select any distinct combos of columns a+b AND select column c
我想选择a+b列的任意组合，然后选择c列
The sql is basically this:
sql基本上是这样的:
SELECT DISTINCT (a, b), c
FROM mytable
Error returned: Operand should contain 1 column(s)
返回的错误:操作数应该包含1列
is this even possible?
这是可能吗?
1 个解决方案
#1
3
You want to use group by instead:
你想用group by代替:
SELECT a, b, c
FROM mytable
group by a, b;
Distinct works on all the columns, not just a few. This formulation returns an arbitrary value of c from one of the rows. More typically, you would choose a value, such as:
不同的作品在所有的列上，而不仅仅是少数。这个公式从其中一行返回任意值c。更典型的是，您将选择一个值，例如:
SELECT a, b, min(c)
FROM mytable
group by a, b;
#1
3
You want to use group by instead:
你想用group by代替:
SELECT a, b, c
FROM mytable
group by a, b;
Distinct works on all the columns, not just a few. This formulation returns an arbitrary value of c from one of the rows. More typically, you would choose a value, such as:
不同的作品在所有的列上，而不仅仅是少数。这个公式从其中一行返回任意值c。更典型的是，您将选择一个值，例如:
SELECT a, b, min(c)
FROM mytable
group by a, b;