How to get left table values only (left join) - mysql

I have two tables:
bloodrequest (id,name,Rphone,bloodtype) as:
reacheduser (id,Rphonw,Dphone) as:
I want to read all data in bloodrequest if bloodrequest.id is not equal to reachedusers.id where reachedusers.Dphone!="618159985"
I have tried left join , subquery but unfortunately nothing work
hear is some code i tried:
SELECT bloodrequest.id, bloodrequest.magac, bloodrequest.bloodType
FROM bloodrequest
LEFT JOIN reachedusers on bloodrequest.id != reachedusers.id
WHERE reachedusers.Dphone != "618159985"
i want to check if request id in table bloodrequest is in reached table where Dphone ="618159985"
if the id is exist but but dphone is not 618159985 i want to read otherwise not


You can use NOT IN (subquery) to find the rows you want, as in:
SELECT
id, magac, bloodType
FROM bloodrequest
WHERE id NOT IN (
SELECT id
FROM reachedusers
WHERE Dphone = "618159985"
)

Related

return values of table 1 based on single column in table 2

I have 3 tables that I am using and need to make a query to return data from one table based on the value of a single column in the second table.
tbl_user
ID
login
pass
active
mscID
tbl_master
ID
name
training_date
MSCUnit
Active
tbl_msc
mscID
mscName
my current SQL statement:
SELECT
tbl_master.ID,
tbl_master.name,
tbl_master.training_date,
tbl_master.MSCUnit,
tbl_master.active,
tbl_user.mscID
FROM
tbl_master,
tbl_user
WHERE
tbl_master.active = 1 AND tbl_master.MSCUnit = tbl_user.mscID
The values stored in tbl_msc.mscID is a varchar(11) and it contains a string similar to A00 or A19. This is also the Primary key in the table.
The values stored in tbl_user.mscID matches that of tbl_msc.mscID. The values stored in tbl_master.UnitMSC also matches that of tbl_msc.mscID.
My goal is to return all records from tbl_master where the currently logged in user has the same mscID. The problem I am having is the statement returns all records in tbl_master.
I have tried several different join statements and for some reason, I cannot get this to filter correctly.
I am missing something. Any assistance in the SQL statement would be appreciated.
Thanks,
Will

You should be writing this using joins. I don't know how you know who the current user is, but the idea is to join the three tables together:
SELECT m.ID, m.name, m.training_date, m.MSCUnit, m.active,
u.mscID
FROM tbl_master m JOIN
tbl_user u
ON m.MSCUnit = u.mscID JOIN
tbl_msc msc
ON msc.mscID = u.msc_ID
WHERE m.active = 1 AND msc.mscName = ?;
Notice the use of proper, explicit, standard JOIN syntax and table aliases.

Select a.*, b.userid from
table_master a, table_user b where
a.mscunit in (select mscid from
table_user where active=1)
This should point you in the right direction.

Returning all records from derived table name that also have IN statements

I'm trying to retrieve a single record from my database, BUT I don't know which table name to query until I query another record.
If I knew the table name and ID the end query would look something like this.
SELECT * FROM `materials_sheet_stock` WHERE `id` = 2
But since I do NOT know the table name or the ID in that table I'm trying to break it up a bit.
This query will successfully retrieve the table name for the above query
SELECT tb1.*
FROM (SELECT `tag_table`
FROM `materials_group_tags_mapping`
WHERE `tag_id` IN
(SELECT `materials_group_tags`.`id`
FROM `materials_group_tags`
WHERE `materials_group_tags`.`name` = "frameless_base_side_material_unexposed")) AS tb1
which in this case is materials_sheet_stock
This query will successfully retrieve the ID that I need for the above query
(SELECT `materials_group_tags_mapping`.`tag_value`
FROM `materials_group_tags_mapping`
WHERE `materials_group_tags_mapping`.`tag_id` IN
(SELECT `materials_group_tags`.`id`
FROM `materials_group_tags`
WHERE `materials_group_tags`.`name` = "frameless_base_side_material_unexposed"))
But now when I put them all together in 1 query using IN it keeps throwing errors about not finding columns, or that all tables need an alias. I've tried editing the following code for like an hour with no luck. Hopefully you guys can spot the error. Here's the final code that I am using.
SELECT tb2.*
FROM (SELECT `tag_table`
FROM `materials_group_tags_mapping`
WHERE `tag_id` IN
(SELECT `materials_group_tags`.`id`
FROM `materials_group_tags`
WHERE `materials_group_tags`.`name` = "frameless_base_side_material_unexposed") ) as tb2
WHERE tb2.`id` IN
(SELECT `materials_group_tags_mapping`.`tag_value`
FROM `materials_group_tags_mapping`
WHERE `materials_group_tags_mapping`.`tag_id` IN
(SELECT `materials_group_tags`.`id`
FROM `materials_group_tags`
WHERE `materials_group_tags`.`name` = "frameless_base_side_material_unexposed"))

MySQL (OSX) LEFT JOIN not working as expected

Hi: struggling with retrieving only those emails from my marketingImport table that do not exist in my hardBounce table.
I tried various approaches to the LEFT JOIN, but I'm always getting the entire marketingTable (all 300K records). I should be only getting about 220K records, since there are about 80K 'bad' emails in my hardBounce table: those should be excluded from my results.
I also tried replacing WHERE with AND (to make it part of the ON clause), but got same results.
This is my SQL:
SELECT marketingImport.email FROM marketingImport
LEFT JOIN hardBounce ON marketingImport.email = hardBounce.email
WHERE hardBounce.email IS NULL;
Tables:
-marketingImport contains a field 'email' which is a varchar(255), nullable index
-hardBounce contains a single field 'email' which is a varchar(255), nullable UNIQUE index (not PK)
What am I missing? I did read all posts...and my eyes are now watering...
Thank you.

How about using a subquery instead of LEFT JOIN?
SELECT marketingImport.email
FROM marketingImport
WHERE marketingImport.email NOT IN (
SELECT hardBounce.email
FROM hardBounce
);

Try to use NOT EXISTS:
SELECT marketingImport.email FROM marketingImport
WHERE NOT EXISTS (
SELECT 1 FROM hardBounce WHERE hardBounce.email = marketingImport.email
);
And I think there may be null value in hardBounce, so you can get all the the emails from marketingImport.

Unknown column 'wp_cons_users.id' in 'on clause'

I have three table one is for users and other one is for subject and third one contain user_id, subject_id foreign keys.
I get unknow coloumn when I run the following sql.
SELECT wp_cons_users.first_name, wp_cons_subject.subject, wp_cons_skilllist.skill_level
FROM `wp_cons_subject`
JOIN wp_cons_skilllist ON wp_cons_skilllist.user_id = wp_cons_users.id
JOIN wp_cons_users ON wp_cons_users.id = wp_cons_skilllist.user_id
WHERE wp_cons_subject.id = '1'
ORDER BY `wp_cons_skilllist`.`skill_level` DESC
I can't find the error with this query.
wp_cons_skilllist
column link to
id (primay)
user_id wp_cons_users -> id
subj_id wp_cons_subject -> id
skill_level
Here I try to get the username, skill level and subject for any given subject id.

Looks like your main problem is with the ordering of your JOINs. In your first join, you are matching with wp_cons_users.id, but you don't join that table until later in the query. If you re-order the joins it should work better. Also, based on your table description, it seems that you will also need to join on subject_id. This query should help:
SELECT wp_cons_users.first_name
, wp_cons_subject.subject
, wp_cons_skilllist.skill_level
FROM wp_cons_users
JOIN `wp_cons_subject`
ON wp_cons_users.id=`wp_cons_subject`.user_id
AND wp_cons_subject.id = '1'
JOIN
wp_cons_skilllist
ON wp_cons_skilllist.user_id = wp_cons_users.id
AND wp_cons_skilllist.subject_id = `wp_cons_subject`.id
ORDER BY `wp_cons_skilllist`.`skill_level` DESC
I am guessing about the field names that weren't in your original query, so you may have to make some changes if they're different from what I'm assuming.

Without information about your attributes in your table, I'm afraid we can only assume that there is no ID column in your wp_cons_users table.

when I corrected the query to following it started to work.
SELECT wp_cons_users.first_name, wp_cons_subject.subject, wp_cons_skilllist.skill_level
FROM `wp_cons_skilllist`
JOIN wp_cons_subject ON wp_cons_subject.id = wp_cons_skilllist.subject_id
JOIN wp_cons_users ON wp_cons_users.id = wp_cons_skilllist.user_id
WHERE wp_cons_skilllist.subject_id = '1'
ORDER BY `wp_cons_skilllist`.`skill_level` DESC
LIMIT 0 , 30

Get a list of ids not present in a table

I have a list of ids, and I want to query a mysql table for ids not present in the table.
e.g.
list_of_ids = [1,2,4]
mysql table
id
1
3
5
6
..
Query should return [2,4] because those are the ids not in the table

since we cant view ur code i can only work on asumption
Try this anyway
SELECT id FROM list_of_ids
WHERE id NOT IN (SELECT id
FROM table)
I hope this helps

There is a horrible text-based hack:
SELECT
substr(result,2,length(result)-2) AS notmatched
FROM (
SELECT
#set:=replace(#set,concat(',',id,','),',') AS result
FROM (
select #set:=concat(',',
'1,2,4' -- your list here
,',')
) AS setinit,
tablename --Your tablename here
) AS innerview
ORDER BY LENGTH(result)
LIMIT 1;

If you represent your ids as a derived table, then you can do this directly in SQL:
select list.val
from (select 1 as val union all
select 2 union all
select 4
) list left outer join
t
on t.id = list.val
where t.id is null;
SQL doesn't really have a "list" type, so your question is ambiguous. If you mean a comma separated string, then a text hack might work. If you mean a table, then something like this might work. If you are constructing the SQL statement, I would advise you to go down this route, because it should be more efficient.