I have two tables, one for students and one for subjects, and I want to join these two tables, so that each student list will contain all subjects belonging to them.
Can this be done in single select query alone?
Or should I query for each table and play with array results?
Table example:
You can use group_concat to get the first option of the desired output:
SELECT student_id, name, GROUP_CONCAT(subject SEPARATOR ' ')
FROM table1
JOIN table2 ON table1.student_id = table2.student_no
GROUP BY student_id, name
Related
I have two tables
Table promos - which has contract table id like ["11,"12"]
Table contract - which has id reference name.
I am trying to get the name from contract table with below sql query but showing error in query
SELECT * FROM promos INNER JOIN contract ON promos.contracts_id=contract.id
Expected Result
Please suggest, how to get this type of ID with query without change IN TABLE.
You can use next query (match records using JSON_CONTAINS and after this group them using JSON_ARRAYAGG:
SELECT contracts_ids, JSON_ARRAYAGG(name)
FROM promos
LEFT JOIN contract ON JSON_CONTAINS(contracts_ids, CONCAT('"', contract.id, '"'))
GROUP BY promos.id, contracts_ids;
Online SQL editor
I have two tables:
procedures
countries
Table procedures has two columns
destination_country_iso
origin_country_iso
Table countries
iso
name
Im trying to join up the two tables in order to get both destination an origin country name from countries table.
SELECT *
FROM draft_procedures AS drp
LEFT JOIN countries AS c1 ON drp.destination_country_iso = c1.iso
LEFT JOIN countries AS c2 ON drp.origin_country_iso = c2.iso
The SQL result display proper result, but I now have two duplicate columns "name" and Im unable to retrieve them with the php code:
$destination_country=$row['c1.name'];
access it like this
SELECT drp.*,c1.name as c1name,c2.name as c2name
then
$row['c1name'] $row['c2name']
I'm creating a website where the user can add some information about multiple computers into a database.
In the mysql database I have 3 tables. TypeOfMachine, Software and Hardware. The only common thing they have is the NumberOfMachine.
I must create a page where the user can run reports showing devices that have a specific piece of software installed (user specified) or specific hardware (user specified) after he submitted the computer's info.
Any ideas how I can do this?
And how I can connect all 3 tables into one?
I thought about this code but i dont know what to put in WHERE. I have 10 variables. and I have to show all the computers with what the user has asked and their info as well!
$search1 = "
SELECT
TypeOfMachine.NumberOfMachine, TypeOfMachine.TypeOfMachine, TypeOfMachine.OS, Software.Software1, Software.Software2, Software.Software3, Hardware.SSD, Hardware.Harddisk, Hardware.MonitorSize, Hardware.Ram, Hardware.Rom, Hardware.Processor
FROM TypeOfMachine, Software, Hardware
WHERE
but i
You want to use a join. This example is based on the fact that you've said the NumberOfMachine field is present in all tables and is a common link between them:
SELECT
TypeOfMachine.NumberOfMachine,
TypeOfMachine.TypeOfMachine,
TypeOfMachine.OS,
Software.Software1,
Software.Software2,
Software.Software3,
Hardware.SSD,
Hardware.Harddisk,
Hardware.MonitorSize,
Hardware.Ram,
Hardware.Rom,
Hardware.Processor
FROM TypeOfMachine
LEFT JOIN Software
ON Software.NumberOfMachine = TypeOfMachine.NumberOfMachine
LEFT JOIN Hardware
ON Hardware.NumberOfMachine = TypeOfMachine.NumberOfMachine
WHERE
...
It's general question, I don't know which tables contains a spesific columns as indicator for all tables. It's about inner and outer join:
The two common types of joins are an inner join and an outer join. The difference between an inner and outer join is in the number of rows included in the results table.
Inner join: The results table produced by an inner join contains only rows that existed in both tables.
Outer join: The combined table produced by an outer join contains all rows that existed in one table with blanks in the columns for the rows that did not exist in the second table.
For instance, if table1 contains a row for Joe and a row for Sally, and table2 contains only a row for Sally, an inner join would contain only one row: the row for Sally. However, an outer join would contain two rows — a row for Joe and a row for Sally — even though the row for Joe would have a blank field for weight.
The results table for the outer join contains all the rows for one table. If any of the rows for that table don’t exist in the second table, the columns for the second table are empty. Clearly, the contents of the results table are determined by which table contributes all its rows, requiring the second table to match it.
Two kinds of outer joins control which table sets the rows and which must match: a LEFT JOIN and a RIGHT JOIN.
You use different SELECT queries for an inner join and the two types of outer joins. The following query is an inner join:
SELECT columnnamelist FROM table1,table2
WHERE table1.col2 = table2.col2
And these queries are outer joins:
SELECT columnnamelist FROM table1 LEFT JOIN table2
ON table1.col1=table2.col2
SELECT columnnamelist FROM table1 RIGHT JOIN table2
ON table1.col1=table2.col2
In all three queries, table1 and table2 are the tables to be joined. You can join more than two tables. In both queries, col1 and col2 are the names of the columns being matched to join the tables. The tables are matched based on the data in these columns. These two columns can have the same name or different names, but they must contain the same type of data.
For general concept you can use #Scrowler suggestion, or this one:
http://stackoverflow.com/questions/1204217/mysql-select-join-3-tables
I would to select some data from mysql. However, some of the data stored in the table I am querying from are in codes and to get the text description I need to reference that data to another table.
TABLE: persons
SELECT id, first_name, last_name, address_code, customer_type_code
FROM persons
WHERE id = 1001
TABLE: ref_address
SELECT address_name FROM ref_address
WHERE address_code = 123
TABLE: ref_customer_type_code
SELECT customer_type_name FROM ref_customer_type_code
WHERE customer_type_code = 456
How can I combine all three queries together to return id, first_name, last_name, address_name, customer_type_name in one query instead of querying them 3 times like this?
Please read the reference manual for join.
In short, you need to define a relation between your tables (I use aliases just to make things a bit "cheaper" to write):
select p.id, p.first_name, p.last_name, p.address_code, p.customer_type_code
, ra.address_name
, rctc.customer_type_name
from persons as p
-- Join the persons table with the ref_address table,
-- using the address_code column of each table
inner join ref_adress as ra
on p.address_code = ra.address_code
-- Join the persons table with the ref_customer_type_code table
-- using the customer_type_code column of each table
inner join ref_customer_type_code as rctc
on p.customer_type_code = rctc.customer_type_code
where p.id = 1001
Notice that when you use multiple tables in a query it may be useful to define aliases to avoid having to write again and again the full name of the table. Also, it may be a good idea to explicitly specify each field's source table (by alias, if you are using it)
What you're looking for is a JOIN.
In a JOIN, you specify two tables and how they are related to one another. In a single SELECT statement, you can have multiple JOIN clauses.
SELECT
p.id, p.first_name, p.last_name, p.address_code, p.customer_type_code,
a.address_name,
t.customer_type_name
FROM
persons p
JOIN ref_address a
ON p.address_code = a.address_code
JOIN ref_customer_type_code t
ON p.customer_type_code = t.customer_type_code
WHERE
p.id = 1001
This query says that the table persons and ref_address should be linked, or "joined", by the related columns address_code which are available in each table. Same goes with the tables persons and ref_customer_type_code being linked by the columns customer_type_code.
I have four tables in a database now asking how can I search the four tables using a single search parameter with PHPMYSQL and display the result in a single page?
thanks alot friends.
Select *
From table1 inner join table2 on table1.col=table2.col
inner join table3 on table#.col=table3.col ..........
where Col=?
you can replace on ?=? with "using (column)" if both tables have the same column name.