Left join using a condition - mysql

I have this issue.
I need to get this fields from my matching table:
date, points
Then i have an epos_id field as well in my matching table..
I have another rbpos_epos table which has epos_id and location field.
I need to get the location from the rbpos_epos using joins.. something like this:
SELECT matching.date, matching.points, matching.time,matching.location,matching.epos_id,rbpos_epos.epos_id,rbpos_epos.location
FROM matching WHERE matching.user_id="'.$id_user.'"
LEFT JOIN rbpos_epos where matching.epos_id=rbpos_epos.epos_id;


SELECT
first_table.date,
first_table.points,
first_table.time,
first_table.location,
first_table.epos_id,
rbpos_epos.epos_id,
rbpos_epos.location
FROM
first_table
LEFT JOIN
rbpos_epos ON first_table.epos_id = rbpos_epos.epos_id
WHERE
first_table.user_id = "'.$id_user.'";


Use on instead where -
SELECT matching.date, matching.points, matching.time,matching.location,matching.epos_id,rbpos_epos.epos_id,rbpos_epos.location
FROM matching LEFT JOIN rbpos_epos ON matching.epos_id=rbpos_epos.epos_id
WHERE matching.user_id="'.$id_user.'";


Try this:
SELECT m.date, m.points, m.time,m.location,m.epos_id,re.epos_id,re.location
FROM matching m
LEFT JOIN rbpos_epos re ON m.epos_id=re.epos_id
WHERE m.user_id= 10

Related

Left join with calculated column and different schemas?

I would like to perform a left join on the following tables:
Vehicles.boats,
vehicle_details.colors
With columns
vehicles.boats.yacht
color_id
where color_id is computed from vehicle_details.colors in a calculation that involves
vehicle_details.colors.sequence
and
vehicle_details.colors.name
I assume the following would serve as my skeleton, but I am unsure of where to put the calculations that define color_id:
SELECT vehicles.boats.yacht, vehicle_details.colors.sequence
FROM vehicles.boats
LEFT JOIN vehicle_details.colors
ON vehicle.boats.colorIdentifier = color_id;
Would it be something like the following, where the calculation is used in the ON portion?
SELECT vehicles.boats.yacht, vehicle_details.colors.sequence
FROM vehicles.boats
LEFT JOIN vehicle_details.colors
ON vehicle.boats.colorIdentifier = *calculations* AS color_id;

In that format you need to do the calculation twice, once for the join condition, once for the display.
SELECT vehicles.boats.yacht, vehicle_details.colors.sequence,*calculations* AS color_id;
FROM vehicles.boats
LEFT JOIN vehicle_details.colors
ON vehicles.boats.colorIdentifier = *calculations*;
You could use a subquery and do it once, something like:
SELECT vehicles.boats.yacht, vehicle_details.colors.sequence, color_id;
FROM vehicles.boats
LEFT JOIN ( Select vehicle_details.colors, *calculations* as colour_id from vehicle_details) as Details_subquery
ON vehicles.boats.colorIdentifier = colour_id ;

Mysql query join table and let fill with empty if value same

I Have problem with joining 2 table
this is mysql query
select *
from tbl_perspective a
inner join tbl_objective b on b.idperspective=a.idperspective
The result is:
Query Result
I Want to display first row of perspectivename and blank or null
Final Result:
enter image description here

Hi Anwr Rawk simply you can use LEFT JOIN
select * from tbl_perspective as a
left join
tbl_objective as b
on b.idperspective=a.idperspective

Join to a subquery which identifies the first row for each idperspective group:
SELECT t1.*
FROM tbl_perspective t1
INNER JOIN
(
SELECT idperspective, MIN(idobjective) AS min_idobjective
FROM tbl_perspective
GROUP BY idperspective
) t2
ON t1.idperspective = t2.idperspective AND
t1.idobjective = t2.min_idobjective;

You need to use LEFT JOIN to include all results, like this : https://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins

How to make LEFT OUTER JOIN except some colums?

I have 3 tables:
First "placement"
Second "user_info"
Third "user_placements"
I want to get all placement data with user infos,
How to do it?
I tried this, but result it not what I expected:
SELECT *, user_placements.id AS user_placements_id, placement.id AS placement_id
FROM placement
LEFT OUTER JOIN user_placements ON placement.id = user_placements.id_placement

you need to one more join with user info
SELECT placement.*,user_info.id as user_info_id,user_info.name as user_name,user_info.mobile as user_mobile
FROM placement LEFT OUTER JOIN user_placements ON placement.id = user_placements.id_placement
LEFT OUTER JOIN user_info ON user_info.id = user_placements.id_user

You are missing the second join:
SELECT *
FROM placement AS p
JOIN user_placements AS up ON p.id = up.id_placement
JOIN user_info AS u ON up.id_user = u.id
Replace the wildcard with the data you want.
You will of course get duplicated data with this query.

Query throwing error; "column ambiguously defined"

I am running a query as
SELECT LOCATION_OID,UPPER(NAME) AS LOCATION_NAME FROM LOCATION LEFT OUTER JOIN LOCATION_CHILD_LOCATION parent on (parent.LOCATION_OID = LOCATION.LOCATION_OID)
There are two table LOCATION and LOCATION_CHILD_LOCATION, Location has some 456 records and location_child_location has 4 records. The records in location_child_location are mapped with the location_oid from the parent i.e location table.
Why is this query giving error?

You need to specify the table from which you want the LOCATION_OID else the analyzer will confuse as to which table it has to look to fetch the data. Try this:
SELECT LOCATION.LOCATION_OID,UPPER(NAME) AS LOCATION_NAME
FROM LOCATION LEFT OUTER JOIN LOCATION_CHILD_LOCATION parent
on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

Try below query where Naming is properly mentioned to avoid conflict in Table Namings:
SELECT l.LOCATION_OID,UPPER(NAME) AS LOCATION_NAME
FROM LOCATION as l
LEFT OUTER JOIN LOCATION_CHILD_LOCATION parent on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

Use aliases for each tables instead of mixing both approach (with and without aliases):
SELECT L.LOCATION_OID
,UPPER(L.NAME) AS LOCATION_NAME
FROM LOCATION L
LEFT OUTER JOIN LOCATION_CHILD_LOCATION P ON P.LOCATION_OID = L.LOCATION_OID
Hope this will help.

You have to add the table name in front of the LOCATION_OID in the select clause:
SELECT LOCATION.LOCATION_OID,UPPER(NAME) AS LOCATION_NAME FROM LOCATION LEFT OUTER JOIN LOCATION_CHILD_LOCATION on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

How to use "case when" from two tables

My database tables, i need to get the "NEW_IC_NO" from these two tables if they found matched.
TB_A
TB_B

Don't use CASE WHEN, use a JOIN:
SELECT a.NEW_IC_NO
FROM TB_A a
INNER JOIN TB_B b ON a.NEW_IC_NO = b.NEW_IC_NO

Use inner join or any join..
Example
Select * from TB_A as A inner join TB_B as B on A.NEW_IC_NO = B.NEW_IC_NO.