将两个SQL查询与不同的where和返回的唯一行组合在一起

Question

I'm trying to combine these 2 SQL queries.

SELECT * FROM `history` WHERE `ID` = 56

SELECT * FROM `live` WHERE `ID` = 56 AND `ACTIVE` = 0 AND t1.`Shown` = 'complete'

I've tried doing something like this:

SELECT t1.*,t2.*
FROM `history` t1
JOIN `live` t2
ON t1.`ID` = 56 AND t1.`ACTIVE` = 0 AND t1.`Shown` = 'complete'
WHERE t2.`ID` = 56

But the query above results in selecting everything from live and forgetting about history .

Expected result: I expect to select all columns from history and live where the ID is equal to 56 . But there will be scenarios where the ID's in history don't exist in live -- in which case I want to select all from history where the ID is equal.

Both tables have different columns. The only thing that they have in common is the ID .

Solution:

Using UNION with specific columns from both tables.

Answer 1

Quick answer is:

SELECT t1.*,t2.*
FROM `live` t1
JOIN `history` t2
ON t1.id = t2.id
WHERE t2.`ID` = 56 AND t1.`ACTIVE` = 0 AND t1.`Shown` = 'complete'

But I guess you should describe your problem with some more details...

Answer 2

Assuming both tables have the same columns, it sounds like you want to use a UNION here.

SELECT Col1, Col2, ..., ColN
    FROM history 
    WHERE ID = 56
UNION
SELECT Col1, Col2, ..., ColN
    FROM live
    WHERE ID = 56 
        AND ACTIVE = 0 
        AND Shown = 'complete'

Answer 3

If the history and live tables have the same number (and preferably type) of columns, then a UNION query might be what you want:

SELECT * FROM `history` WHERE `ID` = 56
UNION ALL
SELECT * FROM `live` WHERE `ID` = 56 AND `ACTIVE` = 0 AND t1.`Shown` = 'complete'

If the number of columns are not the same, then you can choose the same number of columns from both tables to make the query work.

Answer 4

If history and live have same then have the same number (and preferably type) of columns then this could help you

SELECT * FROM 
(
SELECT * FROM `history` WHERE `ID` = 56
UNION ALL
SELECT * FROM `live` WHERE `ID` = 56 AND `ACTIVE` = 0 AND t1.`Shown` = 'complete'
) as result

OR

SELECT * FROM
history h JOIN live l ON
h.id = l.id 
WHERE h.id = 56 AND l.id= 56 AND l.`ACTIVE` = 0 AND l.`Shown` = 'complete'