I have two tables and I want to join them to get the desired output.
Say the 1st table (seat1) is
and the 2nd table (collegestudents) is
The desired output is
I have tried the below code. But it fails to give the desired result.
$rde2=mysqli_query($con, "select * from seat1 s
left JOIN collegestudents c ON c.Roll = s.Roll
");
Any help please.
You want a left join. Your query looks fine, but you would need not to use select *, and instead explictly list the columns that you want to select, using table prefixes. Otherwise, since you have a Roll column in both tables, a name clashes will happen, that your application apparently does not handle well.
select
s.Roll,
c.Name,
s.Subject
from seat1 s
left join collegestudents c on c.Roll = s.Roll
Related
Have these tables
and given post_map.tag_id='1', I would like to get:
entity_type table determines what table be look in, i.e. what table entity_id is stored in. My main goal is to get this table as the result of either mysqli::multi_query() or mysqli::query(), i.e. without PHP going back and forth to the database multiple times; this table may have many many rows and getting this table at once would much more efficient.
My attempts thus far:
I have tried JOIN clause but I don't know how to use the row value of prior SELECT as the table name for the JOIN clause.
Tried Prepared Statments but can't form anything usable.
It can be done by IF() and JOIN. I have solution for you, run below query...
SELECT et.type,
IF(et.type='resource',r.resource_type_id,NULL) AS resource_type_id,
IF(et.type='resource',r.value,NULL) AS value,
IF(et.type='user',u.name,NULL) AS name,
IF(et.type='link',l.source,NULL) AS source,
IF(et.type='link',l.count,NULL) AS count
FROM `post_map` as pm
JOIN `entity_type` as et ON pm.entity_id = et.id
LEFT JOIN `resource` as r ON pm.entity_type_id=r.id
LEFT JOIN `user` as u ON pm.entity_type_id=u.id
LEFT JOIN `link` as l ON pm.entity_type_id=l.id
WHERE pm.tag_id='1'
I'm trying to write a simple interface for a list of companies using MySQL and PHP. So, I want to fetch some information from my database.
Here are my tables:
companies_data - only for system information.
corporate_data - here I want to keep information about big companies.
individual_data - and here I want to keep information about little companies.
So, here is the tables
And here is the query that I've written:
SELECT
a.id,
a.user_id,
a.added,
a.`status`,
a.company_id,
a.company_type,
a.deposit,
a.individual_operations_cache,
a.corporate_operations_cache,
a.physical_operations_cache,
b.full_name,
b.tax_number,
b.address,
b.statement_date,
b.psrn,
c.full_name,
c.tax_number,
c.address,
c.statement_date,
c.psrn
FROM
companies_data a
LEFT OUTER JOIN corporate_data b
ON (a.company_id = b.id) AND a.company_type = 0
LEFT OUTER JOIN individual_data c
ON (a.company_id = c.id) AND a.company_type = 1
WHERE
a.user_id = 3
This is just the code for a test, I'll expand it soon.
As you see, I've got result with extra fields like %field_name%1, %another_field_name%1 and so on. Of course it is not the mysql error - what I've asked that I've got - but I want to remove this fields? It's possible or I must convert this output on the application side?
thos %field_name%1, %another_field_name%1 , are visible since you are selecting them in your query:
b.full_name,
b.tax_number,
b.address,
b.statement_date,
b.psrn,
c.full_name,
c.tax_number,
c.address,
c.statement_date,
c.psrn
When you use fields with the same name in distinct tables, then the result column name come with this identifier field1, field2, fieldn... in order to distinguish from which table does the field come from.
If you want to avoid this names, you can use aliases as follows:
[...]
b.full_name as corporate_full_name,
[...]
Probably, if every common fields are coincident, you won´t need to show them all, so just remove them from the select.
Hope being usefull for you.
Br.
I am having 3 tables (c19 , c19b2, g26) in a database
I want to write a SQL Query to search and display all fields of the matched record.
I am using following query:
$query = "SELECT * FROM c19,c19b2,g26 WHERE armyno LIKE '%$searchTerm%'";
But it only works for table c19,
Data from the other 2 tables is not fetched.Each table has a field armyno
Please help me with this
Thank you.
Alright, you are not looking for a JOIN, but a UNION.
SELECT * FROM c19 WHERE armyno LIKE '%$searchTerm%'
UNION
SELECT * FROM c19b2 WHERE armyno LIKE '%$searchTerm%'
UNION
SELECT * FROM g26 WHERE armyno LIKE '%$searchTerm%'
That will let you query all three tables at the same time.
Which DB are you using? This would have worked in SQL Server. However, notice you are doing a cross join of every record to every record... usually you only want to match some records by restriction of a matching key, for example:
select
*
from a
left join b on b.somekey = a.somekey
left join c on c.someotherkey = b.someotherkey
In SQL server you can just say *, but I'm taking it that in your DB engine that didn't work, so try specifying which table. This may in some environments require aliasing as well:
select
a.*,
b.*,
c.*
from tableA as a
left join tableB as b on b.somekey = a.somekey
left join tableC as c on c.someotherkey = b.someotherkey
Generally, you should see the columns from the first table, followed by the columns from the second table, followed by columns from the third table for a given row. If you wanted to get all columns from all tables, but separately, then that would be 3 separate selects.
Lastly, if all 3 tables have "armyno" then I'd expect it to throw an ambiguous field error. In such case you'd want to specify which table's "armyno" field to filter on.
I have a database with 22 tables most tables have a few column fields with identical names. When I use INNER JOIN on the tables with the duplicate column names it will ignore them in the last table. Right now I am only joining 3 tables
SELECT * FROM company C
INNER JOIN typeofdealer PI ON C.CompanyID = PI.CompanyID
INNER JOIN typeofservices TS ON PI.CompanyID = TS.CompanyID
So in this example typeofdealer and typeofservices both contain column names Other and OtherText When I get this query back I only see one Other and one OtherText.
I just discovered as I was writing this that if I do the query in "phpmyadmin" that I get it back exactly as intended. I am doing this query using prepared statements in php and outputting the results using:
echo "<PRE>";
print_r($results);
echo "</PRE>";
I believe the problem is that php arrays cannot contain duplicate fields so is there a way to circumvent the issue I am having?
The workaround you can do for this is to use an alias AS to make a distinction between columns with the same names. Something like:
SELECT PI.Other AS Other1, PI.OtherText AS OtherText2, TS.Other AS Other2, TS.OtherText AS OtherText2 FROM company C
INNER JOIN typeofdealer PI ON C.CompanyID = PI.CompanyID
INNER JOIN typeofservices TS ON PI.CompanyID = TS.CompanyID
Actually it will work the same way if you omit the AS keyword say SELECT PI.Other Other1, PI.OtherText OtherText2
The problem is, as you rightfully suggested, that PHP won't allow multiple entries into an array with the same key name.
The simplest way around this, is to alias the fields in the column selection section of the query, like so:
SELECT *, typeofservices.Other as ServicesOther, typeofservices.OtherText as ServicesOtherText FROM company C
INNER JOIN typeofdealer PI ON C.CompanyID = PI.CompanyID
INNER JOIN typeofservices TS ON PI.CompanyID = TS.CompanyID
It's not pretty but it's simple.
$sql = mysql_query("SELECT totals.*, sum(totals.payments) as total_payments
FROM totals
INNER JOIN users
GROUP BY totals.idseller;");
When i add the INNER JOIN the sum value is changed. Why?
In my SQL table i have one record in totals width this value: 8943.09 but when i do the some the result is giving me this value: 44715.45
What i am doing wrong?
$sql = mysql_query("SELECT totals.*, sum(totals.payments) as total_payments FROM totals
INNER JOIN users ON totals.idseller = users.idseller
GROUP BY users.UserName;");
Use this Hope this will help you.
When you INNER JOIN to another table, the returned data set is modified to only include rows that exist in both tables. In this case it is likely that there are rows in 'totals' that do not have a matching row in users - either the totals.idseller field might accept null values, or data has become orphaned when matching users have been deleted or edited.
If you want all data in 'totals' regardless of matching user you would user a LEFT JOIN instead in ms-sql, I suspect a similar approach will work in my-sql
You should give an "on" based on the ids. Such as like
inner join users on users.id = totals.idseller
Otherways the sql server will combine all possible rows in the tables, which is most cases not what you wish.
Because when you are adding inner join in your SQL Query, it means you are selecting the data which is common in both the tables.
EX:
SELECT * FROM TABLE_A
INNER JOIN TABLE_B
ON TABLE_A.ID = TABLE_B.ID
If you are joining users table which contains 5 records. By joining table, as there is no any column mapping, this sum-up 5 times and this is reason for showing different values.
Please let me know something wrong in it.
Thanks,
Umehs