My sql:
SELECT * FROM ex_pair
LEFT JOIN ex_currency as client
ON client_curr = currency_id
LEFT JOIN ex_currency as company
ON co_curr = currency_id
I need to get data for two currency_id but I have an error
ambiguous column name: 'currency_id'
Is there any way to do it right or i need to use two queries?
You need to include your alias in your join, like this:
SELECT *
FROM ex_pair
LEFT JOIN ex_currency AS client
ON client_curr = client.currency_id
LEFT JOIN ex_currency as company
ON co_curr = company.currency_id
You may also want to do something other than select * as you will have two tables with the same columns - something like
SELECT pair.*, company.currency_id AS company_currency_id, client.currency_id as client_currency_id, [...]
FROM ex_pair AS pair
[...]
This way when you explicitly declare the columns you intend to use from ex_currency with an alias, you can know on the other end more easily which are client and which are company. You will need to do this for each column in the currency table that you want in your result, though that can be done if you have your table structure in your code easily enough by looping over the list of columns and appending the alias.
$array = [
1=> "currency_id",
2=> "currency_name"
];
$columns = ""
foreach($array as $column){
$columns.= "company.".$column." AS company_".$column;
$columns.= ",client.".$column." AS client_".$column.",";
}
$columns = rtrim($columns,',');
Gives you
company.currency_id AS company_currency_id,client.currency_id AS client_currency_id,company.currency_name AS company_currency_name,client.currency_name AS client_currency_name
Add that after your SELECT pair.* and you get your columns from the currency table, aliased so you know which is which.
you can use the alias that you give to the tables:
SELECT client.currency_id as client_currency, company.currency_id as company_currency
FROM ex_pair
LEFT JOIN ex_currency as client ON client_curr = client.currency_id
LEFT JOIN ex_currency as company ON co_curr = company.currency_id
Related
$sql = 'SELECT *
FROM table_all ta
INNER JOIN table11 ta11
ON ta11.column1 = ta.column1
INNER JOIN table12 ta12
ON ta12.column2 = ta.column2
INNER JOIN table13 ta13
ON ta13.column3 = ta.column3';
This is a sql statement of a PHP-programm that I am currently working on. It works fine actually, but I am unsatisfied with the outcome of this statement. It would be nice to have
only the content of the table_all and then
only the three columns of those other three tables (table11, table12, table13).
The asterisk creates some problems in this regard.
The length of table_all is not known. It is able to change in size.
I tried Union and multiple selects, but only received errors. How would one deal with such a problem?
You can try specifying which columns do you want to get.
As you can see asterisk returns all columns.
You should use something like:
$sql = 'SELECT ta11.column1, taa12.column2, ta13.column13
FROM table_all ta
INNER JOIN table11 ta11
ON ta11.column1 = ta.column1
INNER JOIN table12 ta12
ON ta12.column2 = ta.column2
INNER JOIN table13 ta13
ON ta13.column3 = ta.column3';
I don't see a point in getting ta11.column1, taa12.column2, ta13.column13 because these fields are already in table_all (you use these columns in Join). But you can select any columns you want that way.
Let's say I have this query:
<?
$qi = $db->prepare('SELECT one.id, one.Value, two.Name, three.nfid, temp.Name AS Alias
FROM one
INNER JOIN two ON one.fid = two.id
LEFT OUTER JOIN three ON two.fid = three.fid
LEFT OUTER JOIN (SELECT id,Name FROM two) AS temp ON three.nfid = temp.id
WHERE one.rid = ?
ORDER BY one.id ASC');
$qi->execute( array( $id ) );
?>
Connections between the tables are:
Table one contains a number of rows with the fields one.Value, one.rid and one.fid.
fid is a connection to table two which contains the two.Name of the items (one.fid = two.id).
But sometimes the item is an alias for another item, which is why table three exists. It contains the fields three.fid and three.newfid where three.newfid = two.id (but for another item with another two.Name)
The query is supposed to fetch all rows from one with a certain one.rid and get one.Value, two.Name and if there is an three.fid for this one.fid, get two.Name for three.newfid and call it Alias.
Is there a way to improve this query or solve the problem in another way? Perhaps reshape the layout of the database? It is currently quite slow. The example here have been simplified to make it more general.
Thank you.
The subquery in parentheses forces MYSQL to ignore its indexes, which makes it take a long time. Better to directly join two as temp. As long as you always put two.[field] and temp.[field], it will tell them apart just fine.
SELECT one.id, one.Value, two.Name, three.nfid, temp.Name AS Alias
FROM one
INNER JOIN two ON one.fid = two.id
LEFT OUTER JOIN three ON two.fid = three.fid
LEFT OUTER JOIN two AS temp ON three.nfid = temp.id
WHERE one.rid = ?
ORDER BY one.id ASC
I have 5 mysql tables as described below.
clinics table
id
name
d_location_subscription table
id
clinic_id
t_id //t_id will contain a foreign key of d_cities, d_states or d_countries table
type "country" "state" "city"
d_countries table
id
name
code
d_states table
id
d_country_id
name
code
d_city table
id
d_state_id
name
code
d_location_subscription table is used to record clinic's subscription for a location(it may be a city, state or country). I'm expecting to get all subscribed cities for a specific
clinic using d_location_subscription table.
For example, if clinic A is subscribed to Texas state, I should be able to get all city ids for clinic A.
I created following sql query, it looks ugly but generate a close result what i want to achieve.
select
`d`.`id` AS `clinic_id`,
if((`dct`.`id` is not null),`dct`.`id`,if((`dct1`.`id` is not null),`dct1`.`id`,`dct2`.`id`)) AS `d_city_id`
from ((((((((
`d_location_subscriptions` `dls`
join `clinics` `d`
on((`d`.`id` = `dls`.`clinic_id`)))
left join `d_countries` `dc`
on(((`dc`.`id` = `dls`.`t_id`) and (`dls`.`type` = 'country'))))
left join `d_states` `ds`
on((`ds`.`d_country_id` = `dc`.`id`)))
left join `d_cities` `dct2`
on((`dct2`.`d_state_id` = `ds`.`id`)))
left join `d_states` `ds1`
on(((`ds1`.`id` = `dls`.`t_id`) and (`dls`.`type` = 'state'))))
left join `d_cities` `dct`
on((`dct`.`d_state_id` = `ds1`.`id`)))
left join `d_cities` `dct1`
on(((`dct1`.`id` = `dls`.`t_id`) and (`dls`.`type` = 'city'))))
)
when there is record with type "country" in d_location_subscription table, I receive following result. total number of records returned are equal to the number of d_states table records.
How should I get rid of those Null values by changing above query?
And please advice me if this is the correct way to acheive similar functionality. Thanks in advance :)
The quickest, dirtiest way to achieve what you want is just to append this where condition to your query:
WHERE d_city_id is not null
but you might prefer to rework your query and decide where you really need LEFT joins and not INNER joins
the IF() computed column is in essence what STT LCU was trying to offer, but you can't use that directly in the where for some reason.
I've rewritten your query, but with different aliases to better follow the origination of the tables / relationships to get the data. In the end, I've added a where to test for ANY ONE of the "ID" values as NOT NULL. If they are ALL Null, the record should be excluded..
select
d.id AS clinic_id,
if(CityViaState.id is not null, CityViaState.id,
if( ByCity.id is not null, ByCity.id, CityViaCountry.id )) AS d_city_id
from
d_location_subscriptions dls
join clinics d
ON dls.clinic_id = d.id
left join d_countries ByCountry
ON dls.t_id = ByCountry.id
and dls.type = 'country'
left join d_states StateViaCountry
ON ByCountry.id = StateViaCountry.d_country_id
left join d_cities CityViaCountry
ON StateViaCountry.id = CityViaCountry.d_state_id
left join d_states ByState
ON dls.t_id = ByState.id
and dls.type = 'state'
left join d_cities CityViaState
ON ByState.id = CityViaState.d_state_id
left join d_cities ByCity
ON dls.t_id = ByCity.id
and dls.type = 'city'
where
CityViaState.id is not null
OR ByCity.id is not null
OR CityViaCountry.id is not null
I have two tables and joined them to one different table
1 table named 'rec_dept'
id_dept
id_divisi
nama_dept
2 table named 'rec_divisi'
id_divisi
nama_div
3 joined table named 'rec_divdep'
id_divdep
id_divisi
id_dept
How to get nama_dept where in the same id_divisi?
Maybe you're looking for this:
SELECT `nama_dept` FROM `rec_dept` WHERE `id_divisi` IN (SELECT `id_divisi` FROM `rec_divdep`);
Hope that helps
you can do a SELECT query with a LEFT JOIN function to get data
SELECT a.`nama_dept` FROM `rec_dept` a
LEFT JOIN `rec_divisi` b
ON a.`id_divisi` = b.`id_divisi`
ORDER BY a.`id_divisi` ASC
SELECT documentation
LEFT JOIN documentation
select a.id_dept, a.id_divisi, a.nama_dept, b.id_divisi, b.nama_div, c.id_divdep, c.id_divisi from rec_divdep as c left join rec_divisi as b on (c.id_divisi = b.id_divisi) left join rec_dept as a on (c.id_divisi = a.id_divisi)
what database do you use. I code mine as mysql, basically I condition the three tables that has same id_divisi. I did not test it but I am pretty sure of the logic based on what I understand.
So a user selects from a drop down list a value. I take this value, put it into a variable, then select from the database the ID value of that table A holding the selected value also.
So now I'm trying to use that ID value to get to a many-to-many relationship table that has the selected value from table A to a different table B. The many-to-many relationship table has both IDs. How can I compare this using PHP?
So it would be like:
$A = $_POST['a'];
$sql = "SELECT a, aID from TABLEA WHERE a = $A";
What do I do then to compare the aID with the many-to-many relationships table, then get the other ID in that table and then take that ID to get values from table B?
You can do this with a join in your SQL:
SELECT table_b.* FROM ab_association
LEFT JOIN table_b ON table_b.id = ab_association.b_id
WHERE ab_association.a_id = $specified_id;
That assumes that your many-to-many join table is called ab_association and has two columns, one called a_id that corresponds to table_a.id, and b_id that corresponds to table_b.id.
Update: I removed the table name aliases since they seem to be confusing you.
Another Update: In PHP, here's how you would do that (sans business logic):
<?
// connect to db here
$a_id = mysql_real_escape_string($_POST['a_id']);
$result = mysql_query("SELECT table_b.* FROM ab_association LEFT JOIN table_b ON table_b.id = ab_association.b_id WHERE ab_association.a_id = $a_id;");
// in your view/template
while(false !== (mysql_fetch_object($result))) {
// build your output for each row
}
?>
SELECT *
FROM table_a
LEFT JOIN ab_association ON table_a.aID = ab_association.aID
LEFT JOIN table_b ON table_b.bID = ab_association.bID
WHERE table_a.a = $A
Notes:
I used some underscores in tablenames, so table_a instead of TABLEA (just like Coreyward did) to distinguish between sql and names
You should specify the columns you need instead of 'SELECT *' if many columns aren't needed
You can use JOIN instead of LEFT JOIN if you want get an empty recordset when no match in the many-to-many is found. (Using a LEFT JOIN has the advantage you still have access to the columns in table_A)
it is never wise to use $_POST-vars directly in your queries, this is a serious security risk (SQL injection.)