I'm a total SQL newcomer, I've been working with Access until now and it's time to expand.
I've got two tables I'm working with, Aircraft and Flights.
Aircraft is keyed so that every unique aircraft has an AircraftID and that table contains all the info about that aircraft.
Flights is a list of each individual flight, including AircraftID. I want to have that table (or a new table) listing the same info but with data from the column type in table Aircraft displayed next to the AircraftID.
I can't figure out the lookup to so I can match the AircraftID to the record in the Aircraft table... I'm sure there's an easy way but I just can't make heads or tails of the commands.
SELECT Flights.AircraftID, type --add here all the columns you want to keep from Flights
FROM Flights JOIN Aircraft ON Aircraft.AircraftID = Flights.AircraftID
How to join your tables
You need to use one of the join commands.
There are many type of join, but the two most commonly used are INNER JOIN and LEFT OUTER JOIN.
Since it's a direct mapping, use the INNER JOIN (the default in Microsoft SQL server).
SELECT * FROM Aircraft INNER JOIN Flights ON Aircraft.AircraftID = Flights.AircraftID
Note: * returns every column from the result-set. Return specific columns by comma seperated reference
Example
SELECT Aircraft.Name [Aircraft Name], Flights.Name AS [Flight Name] FROM Aircraft INNER JOIN Flights ON Aircraft.AircraftID = Flights.AircraftID
Related
I am trying to get two tables that aren't related to pull a column of data each.
I have one table called AlphaData and one called TLAuth. Each includes a column that is labelled invoice and I need to pull both columns so I can at least start a comparison. TLAuth will include some of the invoice numbers from AlphaData, but not all of them.
Right now I am using the following code:
SELECT Alphadata.Invoice, TLAuth.Invoice
FROM Alphadata
INNER JOIN TlAuth
ON TLauth.TLAUthID = Alphadata.TLAUthID;
But every time I run this it comes up totally blank. There is definitely data in there, I can pull one column of data from each, but not both at the same time. I have even setup a relationship (1 to Many from TL Auth to Alphadata) and it doesn't seem to work so any help would be grand.
If the tables could not match you should use left join
SELECT Alphadata.Invoice, TLAuth.Invoice
From Alphadata
LEFT JOIN TlAuth ON TLauth.TLAUthID=Alphadata.TLAUthID;
I have an UltraGrid displaying customer information in it. The way the database is set up, there are 2 tables. Customers and Customer_Addresses. I need to be able to display all of the columns from Customers as well as Town and Region from Customer_Addresses, but I'm under the impression that I'd need Town and Region columns in the Customer table to be able to do this? I've never used an INNER JOIN before so I'm not sure if this is true or not, so can anybody give me pointers on how to do this, or if I need the matching columns or not?
Does it even require an INNER JOIN, or is there an alternative way to do this?
Below are the design views of both of the tables - Is it possible to display Add4 and Add5 from Customer_Addresses with all of Customers?
As long as you have another key column you can use to link the tables (ex. ID_Column), it is better that you use LEFT JOIN.
Example:
SELECT c.col1, ... , c.colN, a.town, a.region FROM Customers c
LEFT JOIN Customer_Addresses a ON a.ID_Column = c.ID_Column
In order to clarify how JOIN types work, look at this picture:
In our case, using a LEFT JOIN will take all information from the Customers table, along with any found matching (on ID) information from Customer_Addresses table.
First of all you need some column in common in two tables, all what you have to do is:
CREATE TABLE all_things
AS
SELECT * (or columns that you want to have in the new table)
FROM Costumers AS a1
INNER JOIN Customer_Addresses AS a2 ON a1.column_in_common = a2.column_in_common
The point is what kind of join do you want.
If you can continue the process without having information in table Costumers or in table Customer_Addresses maybe you need OUTER JOIN or other kind of JOIN.
I have the following sample query
select a.name,c.company
from employee a, company c
where a.comp_id = c.comp_id
and a.active='Y'
Now I have two new tables
company_profile, (Profile values for each company. Each company may or may not have data in this table)
profile_defaults (contains default profile values for each profile item independent of company)
Now I need to refer to column "show_data" in company_profile for a specific company. If there is no row for that company then i need to take the value from the profile_defaults table. How do I integrate this logic in the first query which I mentioned above in the best possible way.
Table
Employee
|Name|Comp_id|active|
Company
|Comp_id|Name|
Company_Profile
|comp_profile_id|profile_id|comp_id|profile_name|profile_value|
Profile_Defaults
|profile_id|profile_name|profile_value|
There are many other tables used. But I shortened it for four tables alone for this case now.
Try using this query:
SELECT a.name, c.company, NVL(cp.profile_value, pd.profile_value)
FROM employee a INNER JOIN company c
ON a.comp_id = c.comp_id
LEFT JOIN company_profile cp
ON c.comp_id = cp.comp_id
LEFT JOIN profile_defaults pd
ON cp.profile_id = pd.profile_id
This solution assumes that you have columns comp_id in both the company_profile and default profile_defaults tables to which you can join a record for a given company. As #PM77-1 mentioned, I use NVL() to first check the company_profile table, and default to profile_defaults if nothing is found in the former.
I have two tables: one called EMP_Names which simply stores ID and Employee_Name and another table called EMP_Main which stores the main data and which refers to EMP_Names via IDs. Amongst other fields EMP_Main has fields called Technician_Name_ID and Leader_Name_ID which is related to EMP_Names. My problem is this: how can i run a query where both Technician_Name_ID and Leader_Name_ID resolve to Names? In other words both ID fields refer to the same EMP_Names.ID but I can only establish one relationship between the two tables.
Don't know if I'm clear because it's difficult to explain ...
You can use join but you need multiple joins.
select em.*, ent.name as technician, enl.name as leader
from (emp_main as em left join
emp_names as ent
on em.technician_name_id = ent.id
) left join
emp_names as enl
on em.leader_name_id = enl.id;
These are left joins in case the fields are not populated for all rows.
I have a database with two tables
One with games
and one with participants
A game is able to have more participants and these are in a different table.
Is there a way to combine these two into one query?
Thanks
You can combine them using the JOIN operator.
Something like
SELECT *
FROM games g
INNER JOIN participants p ON p.gameid = g.gameid
Explanation on JOIN operators
INNER JOIN - Match rows between the two tables specified in the INNER
JOIN statement based on one or more
columns having matching data.
Preferably the join is based on
referential integrity enforcing the
relationship between the tables to
ensure data integrity.
o Just to add a little commentary to the basic definitions
above, in general the INNER JOIN
option is considered to be the most
common join needed in applications
and/or queries. Although that is the
case in some environments, it is
really dependent on the database
design, referential integrity and data
needed for the application. As such,
please take the time to understand the
data being requested then select the
proper join option.
o Although most join logic is based on matching values between
the two columns specified, it is
possible to also include logic using
greater than, less than, not equals,
etc.
LEFT OUTER JOIN - Based on the two tables specified in the join
clause, all data is returned from the
left table. On the right table, the
matching data is returned in addition
to NULL values where a record exists
in the left table, but not in the
right table.
o Another item to keep in mind is that the LEFT and RIGHT OUTER
JOIN logic is opposite of one another.
So you can change either the order of
the tables in the specific join
statement or change the JOIN from left
to right or vice versa and get the
same results.
RIGHT OUTER JOIN - Based on the two tables specified in the join
clause, all data is returned from the
right table. On the left table, the
matching data is returned in addition
to NULL values where a record exists
in the right table but not in the left
table.
Self -Join - In this circumstance, the same table is
specified twice with two different
aliases in order to match the data
within the same table.
CROSS JOIN - Based on the two tables specified in the join clause, a
Cartesian product is created if a
WHERE clause does filter the rows.
The size of the Cartesian product is
based on multiplying the number of
rows from the left table by the number
of rows in the right table. Please
heed caution when using a CROSS JOIN.
FULL JOIN - Based on the two tables specified in the join clause,
all data is returned from both tables
regardless of matching data.
example
table Game has columns (gameName, gameID)
table Participant has columns (participantID, participantName, gameID)
the GameID column is the "link" between the 2 tables. you need a common column you can join between 2 tables.
SELECT gameName, participantName
FROM Game g
JOIN Participat p ON g.gameID = p.gameID
This will return a data set of all games and the participants for those games.
The list of games will be redundant unless you structure it some other way due to multiple participants to that game.
sample data
WOW Bob
WOW Jake
StarCraft2 Neal
Warcraft3 James
Warcraft3 Rich
Diablo Chris