I want to join two tables using left join on multiple conditions.
I have two STS_CD flags AC or IA.
I want to get data where STS_CD='AC' but i got it on both AC or IA.
My Query is:
SELECT `bldr`.`id` AS `bldr_ID`,
`bldr`.`sts_cd` AS `bldr_STS_CD`,
bldr.shrt_nm
FROM `bldr`
LEFT JOIN `bldr_img`
ON `bldr`.`id` = `bldr_img`.`prnt_id`
AND `bldr_img`.`img_cat_cd` = 'LG'
AND `bldr`.`sts_cd` = 'AC'
AND `bldr_img`.`sts_cd` = 'AC'
ORDER BY `bldr`.`id`
How do I do this?
This is your query:
SELECT bldr.ID as bldr_ID, bldr.STS_CD AS bldr_STS_CD,bldr.SHRT_NM
FROM bldr LEFT JOIN
bldr_img
ON bldr.ID = bldr_img.PRNT_ID AND
bldr_img.IMG_CAT_CD = 'LG' AND
bldr.STS_CD = 'AC' AND
bldr_img.STS_CD = 'AC'
ORDER BY bldr.ID;
When using LEFT JOIN, conditions on the second table should go in the ON clause. Conditions on the first table should be in the WHERE (except for the JOIN condition, of course). So try this:
SELECT bldr.ID as bldr_ID, bldr.STS_CD AS bldr_STS_CD,bldr.SHRT_NM
FROM bldr LEFT JOIN
bldr_img
ON bldr.ID = bldr_img.PRNT_ID AND
bldr_img.IMG_CAT_CD = 'LG' AND
bldr_img.STS_CD = 'AC'
WHERE bldr.STS_CD = 'AC'
ORDER BY bldr.ID;
Why? Although this seems arcane it makes perfect sense. A LEFT JOIN keeps all rows in the first tables regardless of whether the ON clause evaluates to true, false, or even NULL. It doesn't "know" whether the condition is on the first table or the second. Hence, filters on the first table are not effective.
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 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 trying to return all of the specified event_abr's even if the count is 0.
Here is my SQL Query:
SELECT
basketball_event_types.event_abr,
count(*) value
FROM
basketball_event_types
LEFT OUTER JOIN basketball_game_events on basketball_event_types.id = basketball_game_events.event_type_id
LEFT JOIN users on basketball_game_events.player_id = users.id
WHERE
users.id = 198
AND
basketball_game_events.game_id = 213
AND
(basketball_event_types.event_abr = "TO" OR basketball_event_types.event_abr = "AST")
GROUP BY basketball_event_types.event_abr
However, when I run this, the specified user (198) has 0 AST's for the specified game (213). I want AST -> 0 to pop up, but it just doesn't. The two big things I tried were adding OUTER ot the LEFT JOIN, and I also tried using ifnull(count(*), 0). Neither gave me the result I was looking for.
The filtering needs to be in the on clause. And you need to fix the count():
SELECT bet.event_abr, COUNT(u.id) as value
FROM basketball_event_types bet LEFT JOIN
basketball_game_events bge
ON bet.id = bge.event_type_id AND bge.game_id = 213 LEFT JOIN
users u
ON bge.player_id = u.id AND u.id = 198
WHERE bet.event_abr IN ('TO', 'AST')
GROUP BY bet.event_abr;
Note the changes:
The filtering is moved to the ON clauses -- both filters to the appropriate clauses.
The COUNT() counts the values in the last LEFT JOINed table.
Table aliases make the query easier to write and to read.
IN is simpler than a chain of OR conditions.
I'm populating a table which is fetching the ids from 2 other tables to display their information, for example, delivery has a Hamburguer and the box, but the user might register the delivery with out the box, only with the hamburguer.
When I make a INNER JOIN SELECT to get the data from the DB it will return 0 results since there is no box and I'm trying to compare the ids that don't exist. It doesn't populate the table then.
SELECT
entrega_telemovel.*,
telemovel.id_telemovel,
telemovel.nroserie,
nro_telemovel.numero_telemovel,
nro_telemovel.id_nrotelemovel,
funcionarios.id_funcionario,
funcionarios.nome
FROM entrega_telemovel
INNER JOIN telemovel
ON entrega_telemovel.telemovel = telemovel.id_telemovel
INNER JOIN nro_telemovel
ON nro_telemovel.id_nrotelemovel = entrega_telemovel.numero_telemovel
INNER JOIN funcionarios
ON funcionarios.id_funcionario = entrega_telemovel.funcionario_entrega
ORDER BY funcionarios.nome;
In this query above entrega_telemovel.telemovel=telemovel.id_telemovel the value in entrega_telemovel.telemovel is null like the example I gave above. So 0 results are returned from the query.
How can I solve this ?
You are looking for a LEFT JOIN.
INNER JOIN only combines rows, that exist in both tables. A LEFT JOIN on the other hand always produces at least one row. If on table does not have a match for it, all columns are set to NULL.
SELECT
entrega_telemovel.*,
telemovel.id_telemovel,
telemovel.nroserie,
nro_telemovel.numero_telemovel,
nro_telemovel.id_nrotelemovel,
funcionarios.id_funcionario,
funcionarios.nome
FROM entrega_telemovel
LEFT JOIN telemovel
ON entrega_telemovel.telemovel = telemovel.id_telemovel
LEFT JOIN nro_telemovel
ON nro_telemovel.id_nrotelemovel = entrega_telemovel.numero_telemovel
LEFT JOIN funcionarios
ON funcionarios.id_funcionario = entrega_telemovel.funcionario_entrega
ORDER BY funcionarios.nome;
You want to show all entrega_telemovel entries, no matter whether they have a match in entrega_telemovel or not. This is what an outer join does.
SELECT ...
FROM entrega_telemovel et
LEFT OUTER JOIN telemovel t ON et.telemovel = t.id_telemovel
...
I have the next results from a query. I did this:
Where the user "Adriana Smith" with ID 6 is repeated because she has different contract dates, to do that I did a left join from table bo_users to bo_users_contracts (1:m One to Many Relation). The query is below:
SELECT bo_users.ID, bo_users.display_name, COALESCE (bo_users_contracts.contract_start_date,'-') AS contract_start_date, COALESCE (bo_users_contracts.contract_end_date, '-') AS contract_end_date, COALESCE (bo_users_contracts.current,'-') AS current
FROM bo_users
LEFT JOIN bo_users_contracts ON bo_users.ID = bo_users_contracts.bo_users_id
LEFT JOIN bo_usermeta ON bo_users.ID = bo_usermeta.user_id
WHERE (bo_usermeta.meta_key = 'role' AND bo_usermeta.meta_value = 'member')
But I want to get all users, but from user Adriana I just want to get the occurrence where "current" column = 1.
So the final result would be the 3 user's records:
Alejandro, Rhonda and Adriana (with "current" = 1)
Thank you!
Since you want to limit on a table being outer joined, the limit should be placed on the join itself so the all records from bo_users is retained. (as indicated desired by the outer join)
Essentially the limit is applied before the join so the unmatched records from BO_users to bo_users_contracts are kept. If applied after the join in a where clause the records from BO_user without a matching record would have a null value for current and thus be excluded when the current=1 filter is applied.
In this example the only values which should be in the where would be from table BO_USERS.
I'd even move the bo_usermeta filters to the join or you may lose bo_users; or the left join on the 3rd table should be an inner join.
SELECT bo_users.ID
, bo_users.display_name
, COALESCE (bo_users_contracts.contract_start_date,'-') AS contract_start_date
, COALESCE (bo_users_contracts.contract_end_date, '-') AS contract_end_date
, COALESCE (bo_users_contracts.current,'-') AS current
FROM bo_users
LEFT JOIN bo_users_contracts
ON bo_users.ID = bo_users_contracts.bo_users_id
and bo_users_contracts.current = 1
LEFT JOIN bo_usermeta --This is suspect
ON bo_users.ID = bo_usermeta.user_id
WHERE (bo_usermeta.meta_key = 'role' --this is suspect
AND bo_usermeta.meta_value = 'member') --this is suspect
The lines reading this is suspect are that way because you have a left join which means you want all users from bo_users.. However if a user doesn't have a meta_key or meta_value defined, they would be eliminated. Either change the join to an inner join or move the where clause limits to the join. I indicate this as you're query is "inconsistent" in it's definition leading to ambiguity when later maintained.