SQL Count具有不同且匹配的两个不同表

Question

I have table1 and table2 and I am trying to count the total of unique matches between them for a particular column in each.

select count (distinct phone1) from table1,table2 where table1.phone1=table2.phone2;

I think I am pretty close but I keep getting a syntax error. I am using distinct to get only the unique matches as there are several duplicate matches.

Thanks!

Answer 1

您的查询看起来正确，您只需要删除count和开括号之间的空格，即应该是count(x)而不是count (x)

Answer 2

Try this:

SELECT COUNT(phone)
FROM (
    SELECT phone1 AS phone
    FROM table1
    UNION
    SELECT phone2
    FROM table2
) a

UNION will eliminate the duplicate results and then you just COUNT the resulting records.

From the docs :

UNION is used to combine the result from multiple SELECT statements into a single result set.

The default behavior for UNION is that duplicate rows are removed from the result.

EDIT

I misunderstood the question. I thought you wanted to count all the different numbers.

For that, your query was pretty much ok, appart from the space in between COUNT and (