I have 2 tables A & B
Table A
ID NAME
1 John
2 Jack
3 Mark
Table B
ID phone UserID
s1 4586 1
s2 6996 1
s3 9654 2
they are one to many relation (John has 2 phone on Table 2)
my sql query
$sql = 'SELECT *
FROM
A
Join
B
ON
B.USER_ID = A.ID
WHERE
A.ID=:ID';
my PHP
foreach($vars['GROUPS'] as $row) {
<tr><th>Name</th><td><?=$row['Name']?></td></tr>
<tr><th>phone</th><td><?=$row['phone']?></td></tr>
}
I want to show the phones number for this user John name then show all his details from table 2 . as it now loop for me
You have 2 options:
Use group_concat() function in sql to concatenate all telephone numbers a user has into a single string and use pretty much the same loop in php as you use now.
select a.id, a.name, group_concat(b.phone) as phone
from a inner join b on a.id=b.user_id
group by a.id, a.name
Leave your current sql query intact, but change the php loop displaying the table. In this case only print out a name with all the corresponding phone numbers after looping through all the records returned from the query. Just concatenate all phone numbers in the loop.
I do not know if I understand your question right. From your query you get two rows for the user John, one is "1-John-s1-4586-1" and the other is "1-John-s2-6996-1", right? And you want just one row for that user containing both his phone numbers? Then you could use GROUP_CONCAT:
SELECT A.*, GROUP_CONCAT(b.phone) FROM
A INNER JOIN B ON A.id = B.UserID
WHERE A.ID=:ID
GROUP BY A.id
See the MySQL documentation for more options of the GROUP_CONCAT function: http://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html#function_group-concat
For example, you could use ordering or a custom separator.
In PHP you could use explode() if you want to iterate over the phone numbers.
Related
How would I write a query that would select the name of a person (a column in the row) given that they have enough rows to meet all conditions?
For example, I have a database set up like so:
name permission_id
Bob 1
Bob 2
Jerry 3
Jerry 1
Jose 2
Billy 1
Billy 2
How would I only select the people that have permission id 1 and 2? In other words, I would like a query that checks every person by name to see if they have all the permissions requested.
In this example if I was to check for all users to who have permission 1 and 2 I should get Bob and Billy as a return value.
Here is my current query:
$this->db->select('center_user_permissions.id, center_users.first_name, center_users.last_name');
$this->db->from('center_user_permissions');
$this->db->where_in('permission_id', $permission_ids);
$this->db->join('center_users', 'center_users.center_id = center_user_permissions.center_id');
Currently this query returns anybody who has either permission id 1 or 2. I need it to be 1 AND 2. But I know I can't simply make two wheres because one particular row can't have both permission ids, but the query must check all rows for the specified ids.
I believe I would need a SELECT statement inside of my where? Can anybody tell me if I'm thinking correctly? Thanks.
You can use a in clause an an having for check that the user has both the permission
select name
from center_user_permissions
where permissions_id in (1,2)
group by name
having count(*) = 2
I'm not sure how to build this query in CodeIgniter, but you could INNER JOIN for each permission ID you want the user to have:
SELECT center_users.center_id, center_users.first_name, center_users.last_name
FROM center_users
INNER JOIN center_user_permissions AS p1 ON p1.center_id=center_users.center_id AND p1.permission_id=1
INNER JOIN center_user_permissions AS p2 ON p2.center_id=center_users.center_id AND p2.permission_id=2
You could check for more permissions by adding a INNER JOIN for each additional permission you wanted to require.
MySQL's GROUP BY and HAVING
Not user what kind of DB interface you're using in $this->db, but it may make things a little tricky. If I start with a raw SQL query:
SELECT
center_user_permissions.id,
center_users.first_name,
center_users.last_name
FROM center_user_permissions
LEFT JOIN center_users
ON center_users.center_id = center_user_permissions.center_id
WHERE center_user_permissions.permission_id in (1,2)
Group by name, where count of permission_id is > 1
This will group rows by first_name (so you'll only get one row for each unique name). Doing do allows you to run aggregate functions (SUM(), MAX(), COUNT()) against the rows that were "grouped" into a single row.
SELECT
center_user_permissions.id,
center_users.first_name,
center_users.last_name
FROM center_user_permissions
LEFT JOIN center_users
ON center_users.center_id = center_user_permissions.center_id
GROUP BY center_users.first_name
WHERE center_user_permissions.permission_id in (1,2)
HAVING COUNT(center_user_permissions.permission_id)>1
select distinct(name),.. as name from 'center_user_permissions',center_users where
center_users.center_id = center_user_permissions.center_id and permissions_id in (1,2)
substitute .. with your other fields and put in distinct the value that you want to be unique
That title is really not useful, but its a complex question (in my head, maybe) ... anywho...
Say I have a MySQL table of Countries (A-Z all countries in the world) with id & name
Then I have a table where I am tracking which countries a user has been to: Like so:
Country Table
id name
1 india
2 luxembourg
3 usa
Visited Table
id user_id country_id
1 1 1
2 1 3
Now here's what I want to do, when I present the form to add to the list of visited countries I want country.id 1 & 3 to be excluded from the query result.
I know I can filter this using PHP ... which is something I have done in the past ... but surely there must be a way to structure a query in such a way that 1 & 3 are excluded from the returned results, like:
SELECT *
FROM `countries`
WHERE `id`!= "SELECT `country_id`
FROM `visited`
WHERE `user_id`='1'"
I suspect it has something to do with JOIN statements but I can't quite figure it out.
Bonus gratitude if someone can point me in the right direction with Laravel.
Thanks you all :)
Is this what you want?
select c.*
from countries c left join
visited v
on c.id = v.country_id and v.user_id = 1
where v.country_id is null;
You can also express this as a not in or not exists, but the left join method typically has pretty good performance.
The left outer join keeps all records in the first table regardless of whether or not the on clause evaluates to true. If there are no matches in the second table, then the columns are populated with NULL values. The where clause simply chooses these records -- the ones that do not match.
Here is another way of expressing this that you might find easier to follow:
select c.*
from countries c
where not exists (select 1 from visited where c.id = v.country_id and v.user_id = 1)
You can use your query like this.
SELECT *
FROM `countries` c LEFT JOIN `visited` v on c.id = v.country_id
WHERE v.`country_id` is null
AND v.`user_id` = 1
This is a operation of a LEFT JOIN. What is means is that I'm selecting all registries from the table countries that may or may not is on the table visited based on the ID of the country.
So it will bring you this group
from country from visited
1 1
2 no registry
3 3
So on the where condition (v.country_id is null) I'm saying: I only want the ones that on this left join operation is only on the country table but it is not on visited table so it brings me the id 2. Plus the condition that says that those registries on visited must be from the user_id=1
SELECT * FROM COUNTRIES LEFT JOIN
VISITED ON
countries.id = visited.country_id and visited.country_id NOT IN ( SELECT country_id FROM visited )
if i understand right maybe you need something like this ?
I need to report the number of records that match each of several criteria. For example, how many customers live in each state. I know I can accomplish this through a series of MySQL SELECT statements, but that seems cumbersome and produces a ton of (unnecessary?) MySQL calls.
Can you tell me a better method to use? Can I query the database with one SELECT statement and then use PHP to filter the results to variables?
I'd suggest creating a view for this task just to hide the complexity of the query. Also, in the event that your table schema changes, it is likely that you are still going to want to retrieve this same information from the database. You'd be able to change the view in one place, instead of having to change the queries in, possibly, multiple places to satisfy your schema changes.
I'll just show you the queries, though, since you'd need to know how to do that to create a view anyways.
Sticking with your example of customers living in each state, let's pretend you also want statistics on how many customers share the same last name.
I've setup a mock structure of what your database might be like at this SqlFiddle.
Customers with Same LastName
The following query might be used to get the number of customers with the same last name:
SELECT
LastName AS "Value",
COUNT(*) AS "Count"
FROM Customers
GROUP BY
LastName;
Customers in Same State
Similarly, the customers in the same state might be retrieved with a query as follows:
SELECT
S.Name AS "Value",
COUNT(*) AS "Count"
FROM Customers AS C
INNER JOIN CustomerAddresses AS CA ON C.Id = CA.CustomerId
INNER JOIN Addresses AS A ON CA.AddressId = A.Id
INNER JOIN States AS S ON A.State = S.Id
GROUP BY
A.State;
Getting Your Desired Format
The format that you want is an aggregation of these two queries. You want both returned as a single result set. So, let's workout a schema for the returned table:
ResultType - This will hold a value that corresponds to the type of result. i.e. "State"
Value - This will hold the value of the aggregated column. i.e. "Florida"
Count - This will hold the total number of records that match the aggregated column.
So, now that we have a format, let's create a query that uses our two queries from above, and puts them into this format.
First, I add a new field to each of the above queries: ResultType
For example:
"LastName" AS "ResultType"
Now, I combine my queries into a single query using the UNION ALL statement:
SELECT * FROM (
/* LastName query */
SELECT
"LastName" AS "ResultType",
LastName AS "Value",
COUNT(*) AS "Count"
FROM Customers
GROUP BY
LastName
UNION ALL
/* States query */
SELECT
"State" AS "ResultType",
S.Name AS "Value",
COUNT(*) AS "Count"
FROM Customers AS C
INNER JOIN CustomerAddresses AS CA ON C.Id = CA.CustomerId
INNER JOIN Addresses AS A ON CA.AddressId = A.Id
INNER JOIN States AS S ON A.State = S.Id
GROUP BY
A.State
) AS A
In my SqlFiddle above, this produces an output like:
RESULTTYPE VALUE COUNT
=================================
LastName Jetson 1
LastName Johnson 2
LastName Milton 1
State Florida 2
State Georgia 1
State Utah 1
As you can see, this could get quite complex, so you might consider looking into placing this into a view. Then, you'd be able to query your view, as if it was the table above (ResultType, Value, and Count). That would also allow you to filter on it.
create select query make number of aliens of table and make your related columns aliens which is you want to use.
lest see sample example
SELECT a.id AS id
FROM Table1 AS a
WHERE ...
UNION ALL
SELECT b.name AS name
FROM Table2 AS b
WHERE ...
ORDER BY (a or b) ...
I've got a query to my MySQL database returning four fields of information from a MySQL table (information), which I then encode for JSON using PHP's json_encode() function. Two of the fields it returns are "staffMember" and "lineManager", which return integers that relate to the ID of that person in a (separate) users table.
My query returns the following (in table format):
id is 1
staffMember is 14
lineManager is 12
description is this is a description
etc.. for all the rows.
14 (in the case of the above for example) refers to a row in the users table that would be something like:
id is 14
firstname is dave
secondname is jones
My question is therefore, how can I get the JSON part of the query to return "dave jones" instead of 14? As the info isn't held in the same table in MySQL.
Use LEFT JOIN in your database request like
SELECT a.id, CONCAT(b.firstname, ' ', b.secondname) AS staffMember, a.lineManager, a.description
FROM a
LEFT JOIN b ON (a.staffMember = b.id)
where a and b - your table names
As the commenters mentioned, you will definitely want to add the firstname and lastname fields to your SQL result set. You can do this by altering your query to JOIN to the table that houses your firstname and lastname data. The "ON" clause of your join would be the id common to both tables. An example would be:
SELECT * FROM yourdb.table1 T1 LEFT JOIN yourdb.table2 T2 ON T1.staffMember = T2.id;
I have four tables I want to join and get data from. The tables look something like...
Employees (EmployeeID, GroupID[fk], EmployeeName, PhoneNum)
Positions (PositionID, PositionName)
EmployeePositions (EployeePositionID, EmployeeID[fk], PositionID[fk])
EmployeeGroup (GroupID, GroupName)
[fk] = foreign key
I want to create a query that will return all the information about an employee(given by EmployeeID). I want a query that will return the given employees Name, position(s), and group in one row.
I think it needs to involve joins, but I am not sure how to format the queries. MYSQL's manual is technical beyond my comprehension. I would be very grateful for any help.
It seems you have trouble with SQL, in general, rather than with mySQL in particular. The documentation of mySQL provides details about the various SQL expressions, but generally assume some familiarity with SQL. To get a quick start on SQL you may consider this W3schools.com primer.
The query you need is the following.
SELECT EmployeeName, PositionName, GroupName
FROM Employees E
LEFT JOIN EmployeePositions EP ON EP.EmployeeID = E.EmployeeID
LEFT JOIN Positions P ON P.PositionID = EP.PositionId
LEFT JOIN EmployeeGroup EG ON EG.GroupId = E.GroupId
WHERE E.EmployeeId = some_value
A few things to note:
The 'LEFT' in 'LEFT JOIN' will result in producing NULL in lieu of PositionName or GroupName when the corresponding tables do not have a value for the given FK. (Should only happen if the data is broken, say if for example some employees have GroupId 123 but somehow this groupid was deleted from the EmployeeGroup table.
The query returns one line per employee (1). You could use an alternative search criteria, for example WHERE EmployeeName = 'SMITH', and get a listing of all employees with that name. Indeed without a WHERE clause, you'd get a list of all employees found in Employees table.
(1) that is assuming that each employee can only have one position. If somehow some employees have more than one position (i.e. multiple rows in EmployeePositions for a given EmployeeID), you'd get several rows per employee, the Name and Group being repeated and a distinct PostionName.
Edit:
If a given employee can have multiple positions, you can use the query suggested by Tor Valamo, which uses a GROUP BY construct, with GROUP_CONCAT() to pivot all the possible positions in one single field value in the returned row.
SELECT e.EmployeeID, e.EmployeeName, e.PhoneNum,
g.GroupName, GROUP_CONCAT(p.PositionName) AS Positions
FROM Employees e
LEFT JOIN EmployeeGroup g ON g.GroupID = e.GroupID
LEFT JOIN EmployeePositions ep ON ep.EmployeeID = e.EmployeeID
LEFT JOIN Positions p ON p.PositionID = ep.PositionID
WHERE e.EmployeeID = 1
GROUP BY e.EmployeeID
Returns positions in a comma separated string on one row.