i have 3 table i m merge two table by join but cant Merge more then 3 table
multiple time
$query="select * from emp_table INNER JOIN emp_salary on emp_table.emp_id=emp_salary.emp_id";
how to get get three table data in singe table
A general pattern you might use here would be something like:
SELECT *
FROM emp_table emp
INNER JOIN emp_salary sal
ON emp.emp_id = sal.emp_id
INNER JOIN emp_address addr
ON emp.emp_id = addr.emp_id;
But note that in practice SELECT * should be avoided (I only used it because I don't know in which columns, from which tables, you are interested). Your actual PHP script should only select the columns you really need.
Related
I have two tables.
Table A:
root_id, root_text
Table B:
word_id , word_text,root_text
Now Some of the records of Table B has root_texts which might not exist in Table A.
So for that I am trying to use left join.
select *
from A a , B b
where a.root_text=+b.root_text
I only get the records which has matching root_text.
If I use the new way
Select
*
from
A left join B on a.root_text= b.root_text
I get so many extra records. I am Using MySQL 5.6.1.7
UPDATE :
http://sqlfiddle.com/#!9/7b32a/2
Query I am running
select * from word_detail w left join roots r
on r.root_text =w.root
and w.surah_no=1
and w.verse_no=1
and w.word_no=1
What I am doing wrong ?
As in result you see so many records which are not needed. The filter verse_no , word_no not working.
Update
The issue was after the left join we have to use where
select * from word_detail w left join roots r
on r.root_text =w.root
where w.surah_no=1
and w.verse_no=1
and w.word_no=1
If you want all records from TableB that are not present in table A you should use this:
Select *
from
B left join A
on a.root_text= b.root_text
where
a.root_text is null
or if you want the opposite - all records from tableA that are not present on tableB:
Select *
from
A left join B
on a.root_text= b.root_text
where
b.root_text is null
btw, this is not a left join on MySQL:
select * from A a , B b where a.root_text=+b.root_text
but will result as a simple INNER JOIN
The += operator is not standard SQL, but specific to the Oracle RDBMS, so it will not work as expected on MySQL.
The LEFT JOIN syntax is correct, the "many extra records" stem from the data in your tables. You might want to use some sort of WHERE as a filter or an aggregate to group the result set to make it more managable.
Your first example is an inner join which explains why you are not getting as many results as when you are left joining. Left joining can also be thought of as a left outer join.
I m working in MySQL and have to write a select query.
I have related data in four tables. Now, the parent table may have data whose child data may not be present in lower tables.
I want to write a single query to get data from all four tables, irrespective of situation that data is present in child tables or not.
I have tried to write nested select and joins as below, but m not getting the data.
select * from property p where p.Re_ID in
(select Re_id from entry e where e.Re_ID in
(select Re_id from category c where c.Re_ID in
(select id from re)))
Please help me how to get data from all 4 tables.
If cir_registry is the master, you can select from that and LEFT JOIN the other tables in the order they're distant from cir_registry;
SELECT r.ID rId, r.Description rDescription, c.ID cId ...
...
p.Data_Type pDataType
FROM cir_registry r
LEFT JOIN cir_category c ON c.Registry_ID = r.ID
LEFT JOIN cir_entry e ON e.Category_ID = c.ID
LEFT JOIN cir_property p ON p.Entry_IDInSource = e.IDInSource
You should also alias the columns as above, otherwise, for example, p.ID and c.ID will both show up in the result set as ID, and you'll only be able to access one of them.
You might need UNION? Something like:
Select * FROM cir_registry
Union
Select * FROM cir_entry
Union
Select * FROM cir_property
Check the official doc here: http://dev.mysql.com/doc/refman/5.0/en/union.html
I'm trying to do a select from 2 tables. However in table B I need to get a value from table A.
I'm simplifying this for the sake of ease, but the end result is a very complex query, and this is the only part thats causing problems.
In this example we're using 2 tables - one for members, one for the membership they are linked to.
Here's the code:
SELECT member.id member.name, member.email .membership.type, membership.status FROM
(
(SELECT * FROM tbl_members) AS member,
(SELECT * FROM tbl_memberships WHERE tbl_memberships.memberid = member.id) AS membership
)
The problem is that in the second select query, you cant access member.id, so how would you go about accessing information from the first query, in the second query, if this is even possible. If it isn't possible, what are the other options, bearing in mind a join cant return multiple columns.
But a join can return multiple columns:
SELECT *
FROM tbl_members m
JOIN tbl_memberships ms
ON ms.memberid = m.id
Why don't you use left join, if join is not returning all columns from tbl_members
SELECT *
FROM tbl_members
Left JOIN tbl_memberships
ON tbl_memberships.memberid = tbl_members.id
This is the query that I am using to match up a members name to an id.
SELECT eve_member_list.`characterID` ,eve_member_list.`name`
FROM `eve_mining_op_members`
INNER JOIN eve_member_list ON eve_mining_op_members.characterID = eve_member_list.characterID
WHERE op_id = '20110821105414-741653460';
My issue is that I have two different member lists, one lists are members that belong to our group and the second list is a list of members that do not belong to our group.
How do i write this query so that if a member is not found in the eve_member_list table it will look in the eve_nonmember_member_list table to match the eve_mining_op_members.characterID to the charName
I apologize in advance if the question is hard to read as I am not quite sure how to properly ask what it is that I am looking for.
Change your INNER JOIN to a LEFT JOIN and join with both the tables. Use IFNULL to select the name if it appears in the first table, but if it is NULL (because no match was found) then it will use the value found from the second table.
SELECT
characterID,
IFNULL(eve_member_list.name, eve_nonmember_member_list.charName) AS name
FROM eve_mining_op_members
LEFT JOIN eve_member_list USING (characterID)
LEFT JOIN eve_nonmember_member_list USING (characterID)
WHERE op_id = '20110821105414-741653460';
If you have control of the database design you should also consider if it is possible to redesign your database so that both members and non-members are stored in the same table. You could for example use a boolean to specify whether or not they are members. Or you could create a person table and have information that is only relevant to members stored in a separate memberinfo table with an nullable foreign key from the person table to the memberinfo table. This will make queries relating to both members and non-members easier to write and perform better.
You could try a left join on both tables, and then selecting the non-null results from the resulting query -
select * from
(select * from
eve_mining_op_members as x
left join eve_member_list as y1 on x.characterID = y1.characterID
left join eve_member_list2 as y2 on x.characterID = y2.characterID) as t
where t.name is not null
Or, you could try the same thing with a union and using inner join (assuming joined tables are the same):
select * from
(select * from eve_mining_op_members as x
inner join eve_member_list as y1 on x.characterID = y1.characterID
UNION
select * from eve_mining_op_members as x
inner join eve_member_list2 as y2 on x.characterID = y2.characterID) as t
You can throw in your op_id condition where you see fit (sorry, I didn't really understand where it came from). Good luck!
You have several options but by
using a UNION between the eve_member_list and eve_nonmember_member_list table
and JOIN the results of this UNION with your original eve_mining_op_members table
you will get your required results.
SQL Statement
SELECT lst.`characterID`
, lst.`name`
FROM `eve_mining_op_members` AS m
INNER JOIN (
SELECT characterID
, name
FROM eve_member_list
UNION ALL
SELECT characterID
, name
FROM eve_nonmember_member_list
) AS lst ON lst.characterID = m.characterID
WHERE op_id = '20110821105414-741653460';
I think I'm going down the right path with this one... Please bear with me as my SQL isn't the greatest
I'm trying to query a database to select everything from one table where certain cells don't exist in another. That much doesn't make a lot of sense but I'm hoping this piece of code will
SELECT * from employees WHERE NOT EXISTS (SELECT name FROM eotm_dyn)
So basically I have one table with a list of employees and their details. Then another table with some other details, including their name. Where there name is not in the eotm_dyn table, meaning there is no entry for them, I would like to see exactly who they are, or in other words, see what exactly is missing.
The above query returns nothing, but I know there are 20ish names missing so I've obviously not gotten it right.
Can anyone help?
You didn't join the table in your query.
Your original query will always return nothing unless there are no records at all in eotm_dyn, in which case it will return everything.
Assuming these tables should be joined on employeeID, use the following:
SELECT *
FROM employees e
WHERE NOT EXISTS
(
SELECT null
FROM eotm_dyn d
WHERE d.employeeID = e.id
)
You can join these tables with a LEFT JOIN keyword and filter out the NULL's, but this will likely be less efficient than using NOT EXISTS.
SELECT * FROM employees WHERE name NOT IN (SELECT name FROM eotm_dyn)
OR
SELECT * FROM employees WHERE NOT EXISTS (SELECT * FROM eotm_dyn WHERE eotm_dyn.name = employees.name)
OR
SELECT * FROM employees LEFT OUTER JOIN eotm_dyn ON eotm_dyn.name = employees.name WHERE eotm_dyn IS NULL
You can do a LEFT JOIN and assert the joined column is NULL.
Example:
SELECT * FROM employees a LEFT JOIN eotm_dyn b on (a.joinfield=b.joinfield) WHERE b.name IS NULL
SELECT * from employees
WHERE NOT EXISTS (SELECT name FROM eotm_dyn)
Never returns any records unless eotm_dyn is empty. You need to some kind of criteria on SELECT name FROM eotm_dyn like
SELECT * from employees
WHERE NOT EXISTS (
SELECT name FROM eotm_dyn WHERE eotm_dyn.employeeid = employees.employeeid
)
assuming that the two tables are linked by a foreign key relationship. At this point you could use a variety of other options including a LEFT JOIN. The optimizer will typically handle them the same in most cases, however.
You can also have a look at this related question. That user reported that using a join provided better performance than using a sub query.