[英]Comparing two columns in two different tables
I have two tables A
and B
where table A
has a column X
, table B
has column Y
. 我有两个表
A
和B
,其中表A
有一列X
,表B
有列Y
These columns contain account number information. 这些列包含帐号信息。 I want to check whether the account number information in column
AX
is present in BY
. 我想检查
BY
列中是否存在列AX
的帐号信息。
Note: Both column X
and Y
can have duplicates because these are like composite primary keys. 注意:列
X
和Y
都可以有重复项,因为它们类似于复合主键。
How can I do solve this? 我怎么能解决这个问题?
This will give you account information in table A
that is also present in table B
. 这将为您提供表
A
中的帐户信息,该信息也存在于表B
。 The check is done by a correlated subquery that checks for each row in A
whether the account information is present in B
. 检查由相关子查询完成,该子查询检查
A
每一行是否存在B
的帐户信息。
SELECT DISTINCT
X
FROM
A
WHERE
EXISTS (
SELECT
*
FROM
B
WHERE
B.Y=A.X
);
You can use an INNER JOIN
, like this: 您可以使用
INNER JOIN
,如下所示:
SELECT *
FROM table1 a
INNER JOIN table2 b
ON a.X = b.Y
OR 要么
you can go for IF EXISTS
,like this: 你可以去
IF EXISTS
,像这样:
SELECT *
FROM table1 a
WHERE EXISTS(
SELECT 1
FROM table2 b
WHERE a.x=b.Y )
select distinct(X) 选择不同(X)
from A,B 来自A,B
WHERE AX=BY WHERE AX = BY
This will give you a list of account numbers in A that are not in B: 这将为您提供A中不在B中的帐号列表:
SELECT X FROM (
SELECT DISTINCT X FROM A
) A
LEFT JOIN B ON Y = X
WHERE Y IS NULL
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