Is it possible to OR two separate INNER JOIN's so that the result set contains data from either of the two INNER JOIN's? For instance, is the following possible in MySQL.
SELECT * FROM table1
(INNER JOIN table2 ON table1.column_name=table2.column_name)
OR
(INNER JOIN table3 ON table1.column_name=table3.column_name)
No you cant do this way, one way is to use union
SELECT * FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name
union
SELECT * FROM table1 INNER JOIN table3 ON table1.column_name=table3.column_name
You can use UNION:
SELECT * FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name
UNION DISTINCT
SELECT * FROM table1 INNER JOIN table3 ON table1.column_name=table3.column_name
As described at https://dev.mysql.com/doc/refman/4.1/en/union.html, UNION combines the results of several selects.
you need use where
select * from table1
where
(table1.column_name = (select table2.column_name from table2 inner join table1.column_name as on table1.column_name = table2.column_name))
OR
(table1.column_name = (select table3.column_name from table3 inner join table1.column_name as on table1.column_name = table3.column_name))
work perfect here!
Related
How to search three different tables with three different columns? The current command:
$sql="select t1.brand_name,t2.category_name from brand_data_add AS t1
LEFT JOIN category_add_data AS t2 ON t1.brand_name=t2.category_name
UNION select t1.brand_name,t2.category_name from brand_data_add AS t1
RIGHT JOIN category_add_data AS t2 ON t1.brand_name=t2.category_name";
SQL:
SELECT
*
FROM
(
SELECT
workouts.name,
workouts.description,
`user`.user_email
FROM
workouts
LEFT JOIN `user` ON
workouts.created_by = `user`.iduser
UNION
SELECT
workouts.name,
workouts.description,
`user`.user_email
FROM
workouts
RIGHT JOIN `user` ON
workouts.created_by = `user`.iduser) AS main_table
WHERE
user_email LIKE '%gmail%';
Explanation:
You should enclose your union query with bracket
Fetch the fields with SELECT clause
Use the WHERE clause to do the conditional filter in virtual table main_table (union of two table)
select t1.brand_name,t2.category_name, t3.? from brand_data_add AS t1
LEFT JOIN category_add_data AS t2 ON t1.brand_name=t2.category_name
LEFT JOIN t3 on t3 on t3.? = t?
UNION select t1.brand_name,t2.category_name, t3.? from brand_data_add AS t1
RIGHT JOIN category_add_data AS t2 ON t1.brand_name=t2.category_name"
RIGHT JOIN t3 on t3 on t3.? = t?
This question already has answers here:
Joining three tables using MySQL
(11 answers)
Closed 3 years ago.
i am currently have few 5 table , and i wan to inner join table 1 to table 2, and then table to 2 to table 3, and so on....
i have tried this with few separated inner join, but how to get the same result with only 1 sql
SELECT table1.CW_S_EVT,table2.CW_S_TYP, table2.CW_S_SERVER
FROM table1 INNER JOIN table2
ON table1.CW_S_EVT = table2.CW_S_EVT;
SELECT table2.CW_S_EVT,table2.CW_S_TYP, table3.CW_S_TPL
FROM table2 INNER JOIN table3
ON table2 .CW_S_TYP = table3.CW_S_TYP
SELECT table3.CW_S_TPL, table4.CW_L_TPL,table4.CW_CONTENT
FROM table3 INNER JOIN table4
ON table3.CW_S_TPL = table4.CW_S_TPL
SELECT table1.CW_S_EVT,table5.CW_S_VAR, table5.CW_L_VAR
FROM table1 INNER JOIN table5
ON table1.CW_S_EVT = table5.CW_S_EVT;
This is the code i found on internet but it does not match my case.
SELECT *
FROM table1
INNER JOIN table2
ON table1.primaryKey=table2.table1Id
INNER JOIN table3
ON table1.primaryKey=table3.table1Id
What you need is a left join your tables on your criteria. Since this will result to null values, adding coalesce function will be able to help us give those values that matches your criteria.
Additional distinct keyword if its needed.
SELECT distinct coalesce(table1.CW_S_EVT, table2.CW_S_EVT, table3.CW_S_TPL)
, coalesce(table2.CW_S_TYP, table4.CW_L_TPL, table5.CW_S_VAR)
, coalesce(table2.CW_S_SERVER, table3.CW_S_TPL, table4.CW_CONTENT, table5.CW_L_VAR)
FROM table1
LEFT JOIN table2 ON table1.CW_S_EVT = table2.CW_S_EVT;
LEFT JOIN table3 ON table2.CW_S_TYP = table3.CW_S_TYP
LEFT JOIN table4 ON table3.CW_S_TPL = table4.CW_S_TPL
LEFT JOIN table5 ON table1.CW_S_EVT = table5.CW_S_EVT;
Try this
SELECT
table1.CW_S_EVT as t1_CW_S_EVT,
table2.CW_S_TYP as t2_CW_S_TY,
table2.CW_S_SERVE as t2_CW_S_SERVE,
table2.CW_S_EVT as t2_CW_S_EVT,
table3.CW_S_TPL as t3_CW_S_TPL,
table4.CW_L_TPL as t4_CW_L_TPL,
table4.CW_CONTENT as t4_CW_CONTENT,
table5.CW_S_VAR as t5_CW_S_VAR,
table5.CW_L_VAR as t5_CW_L_VAR
FROM
table1, table2, table3, table4, table5
where
table1.CW_S_EVT = table2.CW_S_EVT AND
table2 .CW_S_TYP = table3.CW_S_TYP AND
table3.CW_S_TPL = table4.CW_S_TPL AND
table1.CW_S_EVT = table5.CW_S_EVT;
SELECT table1.CW_S_EVT,table3.CW_S_TYP,table4.CW_S_TPL, table5.CW_S_VAR
FROM table1
INNER JOIN table2 ON table1.CW_S_EVT = table2.CW_S_EVT
INNER JOIN table3 ON table2.CW_S_TYP = table3.CW_S_TYP
INNER JOIN table4 ON table3.CW_S_TPL = table4.CW_S_TPL
INNER JOIN table5 ON table1.CW_S_EVT = table5.CW_S_EVT
Thanks for all the kind answer, but i found this working at last, juz record here maybe for future use.^^
I have a SQL query:
SELECT table1.column1, table2.column2, table1.column2
FROM table1 LEFT JOIN table2 (ON table1.column1=table2.column2)
What I want to do is add another left join to the table but also to count in that left join data like:
SELECT table1.column1, table2.column2, table1.column2, COUNT(table3.column1)
FROM table1 LEFT JOIN table2 ON table1.column1=table2.column2
LEFT JOIN table3 ON table1.column1=table3.column1
the code does not seems to work, what could be wrong?
count is an aggregate function - you can't mix it with single-row functions without a group by clause. One way around this is to join on a subquery instead of directly on table3 and apply the group by there:
SELECT table1.column1, table2.column2, table1.column2, cnt
FROM table1
LEFT JOIN table2 ON table1.column1 = table2.column2
LEFT JOIN (SELECT column1, COUNT(*) AS cnt
FROM table3
GROUP BY column1) table3 ON table1.column1=table3.column1
Are there significant performance considerations between using UNION versus LEFT OUTER JOIN with OR in the WHERE clause?
What is the difference between these two queries?
Is it often better to use LEFT OUTER JOINs instead of a UNION?
My reason for asking is I actually need to do an INSERT, and can't use a UNION even if I wanted to.
SELECT t.foo
FROM t
INNER JOIN t1 t1.t_id=t.id
WHERE t1.id IN (1,2,3)
UNION
SELECT t.foo
FROM t
INNER JOIN t2 t2.t_id=t.id
INNER JOIN t2a ON t2a.t2_id=t2.id
WHERE t2a.id IN (1,2,3)
UNION
SELECT t.foo
FROM t
INNER JOIN t3 t3.t_id=t.id
INNER JOIN t3a ON t3a.t3_id=t3.id
WHERE t3a.id IN (1,2,3);
SELECT DISTINCT t.foo
FROM t
LEFT OUTER JOIN t1 t1.t_id=t.id
LEFT OUTER JOIN t2 t2.t_id=t.id
LEFT OUTER JOIN t2a ON t2a.t2_id=t2.id
LEFT OUTER JOIN t3 t3.t_id=t.id
LEFT OUTER JOIN t3a ON t3a.t3_id=t3.id
WHERE t1.id IN (1,2,3) OR t2a.id IN (1,2,3) OR t3a.id IN (1,2,3);
UPDATE t
LEFT OUTER JOIN t1 t1.t_id=t.id
LEFT OUTER JOIN t2 t2.t_id=t.id
LEFT OUTER JOIN t2a ON t2a.t2_id=t2.id
LEFT OUTER JOIN t3 t3.t_id=t.id
LEFT OUTER JOIN t3a ON t3a.t3_id=t3.id
SET t.foo="bar"
WHERE t1.id IN (1,2,3) OR t2a.id IN (1,2,3) OR t3a.id IN (1,2,3);
As with many performance questions, you should test the results on your data and your systems. The union and left joins are doing very different things -- and which is better probably depends on features of your data, available indexes, and other considerations.
However, you can use the union method in update. You just need a subquery:
update t join
(select t.id, t1.foo . . .
union . . .
select t.id, t2.foo
) tt
on t.id = tt.id
set t.foo = 'foo'
where . . .;
You might also find it more efficient to use the union approach but to break the update into multiple separate update statements.
You can use UNION in inserts.
INSERT INTO `table`
SELECT * FROM
(
SELECT '1'
UNION
SELECT '2'
) x
Same goes for updates:
UPDATE `table1` t1
JOIN (
SELECT '1' as col1
UNION
SELECT '2'
) x ON x.col1 = t1.colX
SET t1.whateverColumn = "someValue"
As for performance, it's mainly down to indexes. Both can be fast, both can be slow. If you're indexing them correctly, you shouldn't see big differences between the two.
I am trying to find the rows that all four tables share in common.
I tried using this:
SELECT *
FROM TABLE1
INTERSECT
SELECT *
FROM TABLE2
INTERSECT
SELECT *
FROM TABLE3
INTERSECT
SELECT *
FROM TABLE4;
But got no results, i know there are rows that meet this requirement. Because using union instead and adding "order by" i see four rows with the same description from different tables.
Use INNER JOIN with conditions on the fields that you want
ex:
SELECT
t1.*
FROM
TABLE1 t1
INNER JOIN TABLE2 t2
ON t1.field1 = t2.field1
AND t1.field2 = t2.field2
...
INNER JOIN TABLE2 t3
ON t1.field1 = t3.field1
AND t1.field2 = t3.field2
...