I know similar questions have been presented a few times, but it seems these all related to the field value changing based on a specific field value. I actually want to join a completely different table based on the the field value of each record.
I think this is possible with a single query, but since the join table could change every record I'm not sure.
To clarify I have four tables; I am trying to join three of them in a single query. However the third table could be one of two tables depending on the value in each records field.
I would imagine it would look something like this, but its not working.
SELECT crm_deal . * , crm_deal_step.sort_order, COALESCE( CONCAT_WS(' ',crm_lead.first_name, crm_lead.last_name),CONCAT_WS(' ',customer.firstname, customer.lastname) ) AS contact_full_name
FROM `crm_deal`
IF( crm_deal.deal_for = 'lead', LEFT JOIN crm_lead ON crm_deal.deal_for_id = crm_lead.lead_id, LEFT JOIN customer ON crm_deal.deal_for_id = customer.customer_id)
LEFT JOIN crm_deal_step ON crm_deal.deal_step_id = crm_deal_step.deal_step_id
Am I close? Is it possible or do I need to do a php loop and run a second query for every record?
You cant use if stat ment in a select statment.
But you can try this:
SELECT crm_deal . * , crm_deal_step.sort_order,
CASE WHEN crm_lead.first_name is not null AND
crm_lead.last_name is not null
THEN crm_lead.first_name+ ' '+crm_lead.last_name
ELSE customer.firstname +' '+ customer.lastname
END as contact_full_name
FROM `crm_deal`
LEFT JOIN crm_lead ON crm_deal.deal_for_id = crm_lead.lead_id AND crm_deal.deal_for = 'lead'
LEFT JOIN customer ON crm_deal.deal_for_id = customer.customer_id AND crm_deal.deal_for <> 'lead'
LEFT JOIN crm_deal_step ON crm_deal.deal_step_id = crm_deal_step.deal_step_id
Related
I need to retrieve all default settings from the settings table but also grab the character setting if exists for x character.
But this query is only retrieving those settings where character is = 1, not the default settings if the user havent setted anyone.
SELECT `settings`.*, `character_settings`.`value`
FROM (`settings`)
LEFT JOIN `character_settings`
ON `character_settings`.`setting_id` = `settings`.`id`
WHERE `character_settings`.`character_id` = '1'
So i should need something like this:
array(
'0' => array('somekey' => 'keyname', 'value' => 'thevalue'),
'1' => array('somekey2' => 'keyname2'),
'2' => array('somekey3' => 'keyname3')
)
Where key 1 and 2 are the default values when key 0 contains the default value with the character value.
The where clause is filtering away rows where the left join doesn't succeed. Move it to the join:
SELECT `settings`.*, `character_settings`.`value`
FROM `settings`
LEFT JOIN
`character_settings`
ON `character_settings`.`setting_id` = `settings`.`id`
AND `character_settings`.`character_id` = '1'
When making OUTER JOINs (ANSI-89 or ANSI-92), filtration location matters because criteria specified in the ON clause is applied before the JOIN is made. Criteria against an OUTER JOINed table provided in the WHERE clause is applied after the JOIN is made. This can produce very different result sets. In comparison, it doesn't matter for INNER JOINs if the criteria is provided in the ON or WHERE clauses -- the result will be the same.
SELECT s.*,
cs.`value`
FROM SETTINGS s
LEFT JOIN CHARACTER_SETTINGS cs ON cs.setting_id = s.id
AND cs.character_id = 1
If I understand your question correctly you want records from the settings database if they don't have a join accross to the character_settings table or if that joined record has character_id = 1.
You should therefore do
SELECT `settings`.*, `character_settings`.`value`
FROM (`settings`)
LEFT OUTER JOIN `character_settings`
ON `character_settings`.`setting_id` = `settings`.`id`
WHERE `character_settings`.`character_id` = '1' OR
`character_settings`.character_id is NULL
You might find it easier to understand by using a simple subquery
SELECT `settings`.*, (
SELECT `value` FROM `character_settings`
WHERE `character_settings`.`setting_id` = `settings`.`id`
AND `character_settings`.`character_id` = '1') AS cv_value
FROM `settings`
The subquery is allowed to return null, so you don't have to worry about JOIN/WHERE in the main query.
Sometimes, this works faster in MySQL, but compare it against the LEFT JOIN form to see what works best for you.
SELECT s.*, c.value
FROM settings s
LEFT JOIN character_settings c ON c.setting_id = s.id AND c.character_id = '1'
For this problem, as for many others involving non-trivial left joins such as left-joining on inner-joined tables, I find it convenient and somewhat more readable to split the query with a with clause. In your example,
with settings_for_char as (
select setting_id, value from character_settings where character_id = 1
)
select
settings.*,
settings_for_char.value
from
settings
left join settings_for_char on settings_for_char.setting_id = settings.id;
The way I finally understand the top answer is realising (following the Order Of Execution of the SQL query ) that the WHERE clause is applied to the joined table thereby filtering out rows that do not satisfy the WHERE condition from the joined (or output) table. However, moving the WHERE condition to the ON clause applies it to the individual tables prior to joining. This enables the left join to retain rows from the left table even though some column entries of those rows (entries from the right tables) do not satisfy the WHERE condition.
The result is correct based on the SQL statement. Left join returns all values from the right table, and only matching values from the left table.
ID and NAME columns are from the right side table, so are returned.
Score is from the left table, and 30 is returned, as this value relates to Name "Flow". The other Names are NULL as they do not relate to Name "Flow".
The below would return the result you were expecting:
SELECT a.*, b.Score
FROM #Table1 a
LEFT JOIN #Table2 b
ON a.ID = b.T1_ID
WHERE 1=1
AND a.Name = 'Flow'
The SQL applies a filter on the right hand table.
I am using the following mysql to look at user subscriptions. I need to get all the users and in one column show if they have an active subscription or not
This is what I have tried:
SELECT `general`.`exchange`.`email`,substring_index(`general`.`exchange`.`name`, " ", 1) as name, `courses`.`courseSubscriptions`.`expiryTimestamp`
FROM `general`.`exchange`
LEFT JOIN `courses`.`courseSubscriptions`
ON `courses`.`courseSubscriptions`.`memberID` = `general`.`exchange`.`id`
WHERE (`courses`.`courseSubscriptions`.memberID = `general`.`exchange`.`id`)
AND (`courses`.`courseSubscriptions`.expiryTimestamp > 1443975741)
The problem is that it is only returning users who have a subscription. I need it to return all users, and show in a column who has a subscription or not
How can I do this?
Your where clause is turning the left join into an inner join. Also, table aliases would make the query easier to write and to read:
SELECT e.`email`, substring_index(e.`name`, ' ', 1) as name, cs.`expiryTimestamp`
FROM `general`.`exchange` e LEFT JOIN
`courses`.`courseSubscriptions` cs
ON cs.`memberID` = e.`id` AND (cs.expiryTimestamp > 1443975741) ;
The solution to the LEFT JOIN problem is to move the condition on the second table into the ON clause. Also, you don't need to repeat the join conditions.
If you want a flag, you can add that:
SELECT e.`email`, substring_index(e.`name`, ' ', 1) as name, cs.`expiryTimestamp`,
(cs.`expiryTimestamp` is not null) as isActiveFlag
FROM `general`.`exchange` e LEFT JOIN
`courses`.`courseSubscriptions` cs
ON cs.`memberID` = e.`id` AND (cs.expiryTimestamp > 1443975741) ;
You've repeated the join condition in the where clause. Since null will never return true in an equality check, this effectively removes the users without any courses and turns your outer join to an inner join. Similarly, the condition on the course's time should also be moved to the join clause:
SELECT `general`.`exchange`.`email`,
SUBSTRING_INDEX(`general`.`exchange`.`name`, " ", 1) AS name,
`courses`.`courseSubscriptions`.`expiryTimestamp`
FROM `general`.`exchange`
LEFT JOIN `courses`.`courseSubscriptions` ON
`courses`.`courseSubscriptions`.`memberID` =
`general`.`exchange`.`id` AND
`courses`.`courseSubscriptions`.expiryTimestamp > 1443975741
Table Name: Look
FieldName: LookUp
example fieldname value : Country.CountryCode
While making a select inside table 'Look' I should dynamically split on value of the fieldname 'LookUp' and get the first value as Tablename and second value as Fieldname to do a dynamic select. I have the split function in place the problem is how to make it work in a case statement or maybe somebody has an alternative solution. currently i have this which is clearly not working
SELECT l.Id,
case when l.lookup is not null then
SELECT t.Id
FROM (SPLIT_STR(l.LOOKUP,'.',1)) AS t
WHERE t.(SPLIT_STR(l.LOOKUP,'.',2)) = l.attValue
LIMIT 1
END AS attValue
FROM look as l
Don't believe it is possible to pick up the table name from a field. Does suggest that there is an issue with your database design though.
Previous similar question:-
MYSQL query using variable as table name in LEFT JOIN
If there is a limited number of related tables / fields to join on and you know them all in advance then something like the following might do it:-
SELECT l.Id,
CASE
WHEN SPLIT_STR(l.LOOKUP,'.',1) = 'tableA' THEN tableA.Id
WHEN SPLIT_STR(l.LOOKUP,'.',1) = 'tableB' THEN tableB.Id
WHEN SPLIT_STR(l.LOOKUP,'.',1) = 'tableC' THEN tableC.Id
WHEN SPLIT_STR(l.LOOKUP,'.',1) = 'tableD' THEN tableD.Id
ELSE NULL
END AS SubId
FROM look as l
LEFT OUTER JOIN tableA ON tableA.ColA = l.attValue
LEFT OUTER JOIN tableB ON tableA.ColB = l.attValue
LEFT OUTER JOIN tableC ON tableA.ColC = l.attValue
LEFT OUTER JOIN tableD ON tableA.ColD = l.attValue
Ie, join against every possible sub table and use a CASE to return the field from the one you want.
But if you are reduced to doing this then I would suggest redesigning the database at the earliest opportunity.
We have two tables that I need to join on where a column (which, at this point, I can't change how/what values are used in that column) aren't using the same value. So depending on the value of the column in the first table, I need to join/select a particular value in the second table. Here is an example (which obviously doesn't work) of what I am trying to do:
SELECT Alert.*, Comments.Comment FROM
Alert
LEFT OUTER JOIN Comments ON Comments.ObjectId = Alert.ObjectId AND
CASE
WHEN Alert.ObjectType = 'U' THEN Comments.ObjectType = 'USER'
WHEN Alert.ObjectType = 'E' THEN Comments.ObjectType = 'EVENT'
END CASE
So I want everything from the Alert table and, if there are corresponding records in the Comments table, I want those, too. But only for the appropriate/matching ObjectType.
I've tried this using both CASE and IF but I can't seem to get it to work. Is something like this possible?
The CASE statement is made to return a value, not to perform an operation.
Also change the last END CASE to just END.
Use that returned value to compare with in the join condition.
Try:
SELECT Alert.*, Comments.Comment FROM
Alert
LEFT OUTER JOIN Comments ON Comments.ObjectId = Alert.ObjectId AND
Comments.ObjectType =
CASE Alert.ObjectType
WHEN 'U' THEN 'USER'
WHEN 'E' THEN 'EVENT'
END
I recommend you handle this with a UNION. In one union join the user comments in another the event comments:
SELECT Alert.*, userComments.Comment
FROM alert
LEFT OUTER JOIN comments usercomments ON userComments.ObjectId = Alert.ObjectId AND usercomments.objecttype='USER'
WHERE alert.objecttype = 'U'
UNION
SELECT Alert.*, eventComments.Comment
FROM alert
LEFT OUTER JOIN comments eventcomments ON eventComments.ObjectId = Alert.ObjectId AND eventcomments.objecttype='EVENT'
WHERE alert.objecttype = 'E'
You don't have to alias them they way I did - it just helps readability.
Why not just:
SELECT Alert.*, Comments.Comment FROM
Alert
LEFT OUTER JOIN Comments ON Comments.ObjectId = Alert.ObjectId AND
Alert.ObjectType = LEFT(Comments.ObjectType, 1);
It seems a lot simpler...
EDIT
Based on your comment, it seems that not all 'matching' values start with the same letter. In this case, I would recommend designing an intermediate table with columns AlertType char(1) and CommentType varchar(50). Insert each combination of TypeId, like U, User; E, Event; etc. The you can modify your SQL to read
SELECT Alert.*, Comments.Comment FROM
Alert
LEFT OUTER JOIN Intermediate i on Alert.ObjectType = i.AlertType
LEFT OUTER JOIN Comments ON Comments.ObjectId = Alert.ObjectId AND
Comments.ObjectType = i.CommentType;
I have this query:
SELECT p.text,se.name,s.sub_name,SUM((p.volume / (SELECT SUM(p.volume)
FROM phrase p
WHERE p.volume IS NOT NULL) * sp.position))
AS `index`
FROM phrase p
LEFT JOIN `position` sp ON sp.phrase_id = p.id
LEFT JOIN `engines` se ON se.id = sp.engine_id
LEFT JOIN item s ON s.id = sp.site_id
WHERE p.volume IS NOT NULL
AND s.ignored = 0
GROUP BY se.name,s.sub_name
ORDER BY se.name,s.sub_name
There are a few things I want to do with it:
1) The end of the calculation for 'index', I multiple it all by sp.position, then get it's SUM. If there is NO MATCH in the first LEFT JOIN 'position', I want to give sp.position a value of 200. So basically if in the 'phrase' table I have an ID=2, but that does not exist in sp.phrase_id in the entire 'position' table, then sp.position=200 for the 'index' calculation, otherwise it will it will be whatever value is stored in the 'position' table. I hope that makes sense.
2) I do a GROUP BY se.name. I would like to actually SUM the entire 'index' values for similar se.name fields. So in the resultset as it stands now, if there were 20 p.text rows with the same se.name, I would like to SUM the index column for the same se.name(s).
I am more of a PHP guy, but trying to learn more MySQL. I have become a big believer in making the DB do as much of the work as possible instead of trying to manipulate the dataset after it's been returned.
I hope the questions were clear. Anyways, can both 1) and 2) be done? There's much more I want to modify this query to do, but I think if I need more help in the future on it, it would require a different question.
The position table has a engines_id, phrase_id, item_id which will make it a unique entry. The value I am trying to calculate is the sp.position value. But there are cases when there is no entry for these IDs combined. If there is no entry for the combo of 3 IDs I just listed, I would like to use sp.position=200 in my calculation.
How's this:
select x.name, sum(index) from
(
SELECT p.text,se.name,s.sub_name,SUM((p.volume / (SELECT SUM(p.volume)
FROM phrase p
WHERE p.volume IS NOT NULL) * if(sp.position is null,200,sp.position)))
AS `index`
FROM phrase p
LEFT JOIN `position` sp ON sp.phrase_id = p.id
LEFT JOIN `engines` se ON se.id = sp.engine_id
LEFT JOIN item s ON s.id = sp.site_id
WHERE p.volume IS NOT NULL
AND s.ignored = 0
GROUP BY se.name,s.sub_name
ORDER BY se.name,s.sub_name
)x
GROUP BY x.name
Try the following:
1.) Use IFNULL(), in your case IFNULL(sp.position, 200)
2.) I am not entirely clear on this part, but it seems like you already have part of what you are asking.