I'm not sure if I'm using the correct terminology.
SELECT movies.*, actors.`First Name`, actors.`Last Name`
From movies
Inner Join actors on movies.`actor1` Where movies.`actor1` = actors.`indexActors`;
#Inner Join actors on movies.`actor2` Where movies.`actor2` = actors.`indexActors`;
I have the 2nd line commented out, each one works individually, and I'm wondering how to combine them.
2ndly, when I execute the query, I get the results:
ID Title Runtime Rating Actor1 Actor2 First Name Last Name
1 Se7en 127 R 1 2 Morgan Freeman
2 Bruce Almighty 101 PG-13 1 3 Morgan Freeman
3 Mr. Popper's Penguins 94 PG 3 4 Jim Carrey
4 Superbad 113 R 4 5 Emma Stone
5 Crazy, Stupid, Love. 118 PG-13 4 Null Emma Stone
Is there a way to add the results from the 2nd join to the rightmost columns?
Also, is it possible to combine the strings/VARCHARs from First Name and Last Name, and then have that value show up under the corresponding Actor Field?
(aka the field under Actor 1 for row 1 would be "Morgan Freeman" instead of "1")
Thanks.
Your sql is not valid, but you can achieve your goal by joining to the same table twice, with different aliases. This sort of thing
select blah blah blah
from table1 t1 join table2 t2 on t1.field1 = t2.field1
join table2 t2_again on t1.field1 = t2_again.field2
etc
As far as joining first and last names in a single field, most databases have a way to concatenate strings, but they are not all the same. You'll have to specify your db engine.
Related
I've reviewed multiple Q&A involving TOP 1 and CROSS APPLY (including the very informative 2043259), but I still can't figure out how to solve my issue. If I had a single join I'd be fine, but fitting TOP 1 into the middle of a chain of joins has stumped me.
I have four tables and one of the tables contains multiple matches when joining due to a previous bug (since fixed) that created new records in the table instead of updating existing records. In all cases, where there are multiple records, it is the top-most record that I want to use in one of my joins. I don't have access to the table to clean up the extraneous data, so I just have to deal with it.
The purpose of my query is to return a list of all "Buildings" managed by a particular person (user choses a person's name and they get back a list of all buildings managed by that person). My tables are:
Building (a list of all buildings):
BuildingId BuildingName
1 Oak Tree Lane
2 Lighthoue Court
3 Fairview Lane
4 Starview Heights
WebBuildingMapping (mapping of BuidingId from Building table, that is part of an old system, and corresponding WebBuildingId in another piece of software):
BuildingId WebBuildingId
1 201
2 202
3 203
4 204
WebBuildingContacts (list of ContactID for the building manager of each building). This is the table with duplicate values - where I want to choose the TOP 1. In sample data below, there are two references to WebBuidingId = 203 (row 3 & row 5) - I only want to use row 3 data in my join.
Id WebBuildingId ContactId
1 201 1301
2 202 1301
3 203 1303
4 204 1302
5 203 1302
Contacts (list of ContactIds and corresponding property manager Names)
ContactId FullName
1301 John
1302 Mike
1303 Judy
As noted, in the example above, the table WebBuildingContact has two entries for the building with a WebBuidingId = 203 (row 3 and row 5). In my query, I want to select the top one (row 3).
My original query for a list of buildings managed by 'Mike' is:
SELECT BuildingName
FROM Building bu
JOIN WebBuildingMapping wbm ON wbm.BuildingId = bu.BuildingId
JOIN WebBuildingContact wbc ON wbc.WebBuildingId = wbm.WebBuildingId
JOIN Contacts co ON co.ContactId = wbc.ContactId
WHERE co.FullName = 'Mike'
This returns 'Fairview Lane' and 'Starview Heights'; however, Judy manages 'Fairview Lane' (she's the top entry in the WebBuildingContacts table). To modify the query and eliminate row 5 in WebBuildingContacts from the join, I did the following:
SELECT BuildingName
FROM Building bu
JOIN WebBuildingMapping wbm ON wbm.BuildingId = bu.BuildingId
JOIN WebBuildingContact wbc ON wbc.WebBuildingId =
(
SELECT TOP 1 WebBuildingId
FROM WebBuildingContact
WHERE WebBuildingContact.WebBuildingId = wbm.WebBuildingId
)
JOIN Contacts co ON co.ContactId = wbc.ContactId
WHERE co.FullName = 'Mike'
When I try this; however, I get the same result set (ie it returns 'Mike' as manager for 2 buildings). I've also made various attempts to use CROSS APPLY but I just end up with 'The multi-part identifier could not be bound', which is a whole other rabbit hole to go down.
You could try this:
SELECT bu2.BuildingName
FROM building bu2
WHERE bu2.BuildingId IN
(SELECT MAX(bu.BuildingId)
FROM Building bu
JOIN WebBuildingMapping wbm ON wbm.BuildingId = bu.BuildingId
JOIN WebBuildingContact wbc ON wbc.WebBuildingId = wbm.WebBuildingId
JOIN Contacts co ON co.ContactId = wbc.ContactId
WHERE co.FullName = 'Mike'
);
I have two tables in MS Access that have the same Name_ID column, the only problem is that they differ slightly. Name_ID in table 1 looks like this:
Name_ID
Newton, Kate Little
River, Jane Armen
Barker, Bob Jep
Jake, Lee
And in table 2 it looks like this:
Name_ID
NEWTON, KATE L MD
RIVER, JANE A DO MS
BARKER, BOB J. (MD)
JAKE, LEE I.
I'm struggling with how to join the tables. I tried doing a join using like, based on Access/SQL Server 2008 Join using Like not working, but it's not working:
Select table1.*, table2.col from table1
left join
table2
on table1.Name_ID like '*' & table2.Name_ID & '*';
I also tried:
Select table1.*, table2.col from table1
left join
table2
on instr(table1.Name_ID, table2.Name_ID) > 0;
Both queries execute, but return blank columns. Any idea why it's not working, or a better way?
Both queries are looking for a full name string within another full name string. How would you expect Newton, Kate Little to match to *NEWTON, KATE L MD*? And for the second query, NEWTON, KATE L MD is not within Newton, Kate Little.
Probably best can do is extract last name part and match on that. Assumes names are not repeated and not multiple people with same last name and always last name followed by a comma.
SELECT Table1.Name_ID, Table2.Name_ID
FROM Table1 LEFT JOIN Table2
ON Table1.Name_ID LIKE Left(Table2.Name_ID, InStr(Table2.Name_ID,",")) & "*";
I have a counselling appointment website. Currently I list clients in one table, but also have couples listed by id in a second table for when they book a couples session. ie:
client
id_no first last
564 John Smith
983 Mary Jones
999 Mark Fields
882 Joan Hancock
couple
id_no client1 client2
623 564 983
555 999 882
I would like to write a single select statement, using aliases, which will list out couples on a single line. Up until now, I have been doing a simple join then cleaning up the result using php after running the query, but would like to clean this up in sql so that I get a result like the following
id_no first_1 last_1 first_2 last_2
623 John Smith Mary Jones
555 Mark Fields Joan Hancock
I suspect that sub queries might be involved, but can't for the life of me wrangle them to get this result.
Update
I just tried the following:
SELECT id_no,first_1,last_1,first_2,last_2
FROM ( SELECT a.id_no AS id_no, b.first AS first_1,b.last AS last_1
FROM couple AS a, client AS b WHERE a.client1=b.id_no ) c1
JOIN ( SELECT a.id_no AS id_no, b.first AS first_2,b.last AS last_2
FROM couple AS a, client AS b WHERE a.client2=b.id_no ) c2 ON
(c1.id_no=c2.id_no)
And am getting a message that "Column 'id_no' in field list is ambiguous". Not sure if I am on the right track
You are getting the exception because you did not specified the table alias to id_no as this column belongs to both tables, so SQL is not sure which column to return, so it will throw ambiguous column error.
Also you don't have to use sub queries, you just need to join client table twice with couple table, one for client1 and other one for client2 like below
Select cp.id_no,
cl1.first as first_1,
cl1.last as last_1,
cl2.first as first_2,
cl2.last as last_2
From couple cp
inner join client cl1 on cl1.id_no = cp.client1
inner join client cl2 on cl2.id_no = cp.client2
My problem is Play! Framework / JPA specific. But I think it's applicable to general SQL syntax.
Here is a sample query with a simple JOIN:
return Post.find(
"select distinct p from Post p join p.tags as t where t.name = ?", tag
).fetch();
It's simple and works well.
My question is: What if I want to JOIN on more values in the same table?
Example (Doesn't work. It's a pseudo-syntax I created):
return Post.find(
"select distinct p from Post p join p.tags1 as t, p.tags2 as u, p.tags3 as v where t.name = ?, u.name = ?, v.name = ?", tag1, tag2, tag3,
).fetch();
Your programming logic seems okay, but the SQL statement needs some work. Seems you're new to SQL, and as you pointed out, you don't seem to understand what a JOIN is.
You're trying to select data from 4 tables named POST, TAG1, TAG2, and TAG3.
I don't know what's in these tables, and it's hard to give sample SQL statements without that information. So, I'm going to make something up, just for the purposes of discussion. Let's say that table POST has 6 columns, and there's 8 rows of data in it.
P Fname Lname Country Color Headgear
- ----- ----- ------- ----- --------
1 Alex Andrews 1 1 0
2 Bob Barker 2 3 0
3 Chuck Conners 1 5 0
4 Don Duck 3 6 1
5 Ed Edwards 2 4 2
6 Frank Farkle 4 2 1
7 Geoff Good 1 1 0
8 Hank Howard 1 3 0
We'll say that TAG1, TAG2, and TAG3 are lookup tables, with only 2 columns each. Table TAG1 has 4 country codes:
C Name
- -------
1 USA
2 France
3 Germany
4 Spain
Table TAG2 has 6 Color codes:
C Name
- ------
1 Red
2 Orange
3 Yellow
4 Green
5 Blue
6 Violet
Table TAG3 has 4 Headgear codes:
C Name
- -------
0 None
1 Glasses
2 Hat
3 Monacle
Now, when you select data from these 4 tables, for P=6, you're trying to get something like this:
Fname Lname Country Color Headgear
----- ------ ------- ------ -------
Frank Farkle Spain Orange None
First thing, let's look at your WHERE clause:
where t.name = ?, u.name = ?, v.name = ?
Sorry, but using commas like this is a syntax error. Normally you only want to find data where all 3 conditions are true; you do this by using AND:
where t.name=? AND u.name=? AND v.name=?
Second, why are you joining tables together? Because you need more information. Table POST says that Frank's COUNTRY value is 4; table TAG1 says that 4 means Spain. So we need to "join" these tables together.
The ancient (before 1980, I think) way to join tables is to list more than one table name in the FROM clause, separated by commas. This gives us:
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P, TAG1 T, TAG2 U, TAG3 V
The trouble with this query is that you're not telling it WHICH rows you want, or how they relate to each other. So the database generates something called a "Cartesian Product". It's extremely rare that you want a Cartesian Product - normally this is a HUGE MISTAKE. Even though your database only has 22 rows in it, this SELECT statement is going to return 768 rows of data:
Alex Andrews USA Red None
Alex Andrews USA Red Glasses
Alex Andrews USA Red Hat
Alex Andrews USA Red Monacle
Alex Andrews USA Orange None
Alex Andrews USA Orange Glasses
...
Hank Howard Spain Violet Monacle
That's right, it returns every possible combination of data from the 4 tables. Imagine for a second that the POST table eventually grows to 20000 rows, and the three TAG tables have 100 rows each. The whole database would be less than a megabyte, but the Cartesian Product would have 20,000,000,000 rows of data -- probably about 120 GB of data. Any database engine would choke on that.
So if you want to use the Ancient way of specifying tables, it is VERY IMPORTANT to make sure that your WHERE clause shows the relationship between every table you're querying. This makes a lot more sense:
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P, TAG1 T, TAG2 U, TAG3 V
WHERE P.Country=T.C AND P.Color=U.C AND P.Headgear=V.C
This only returns 8 rows of data.
Using the Ancient way, it's easy to accidentally create Cartesian Products, which are almost always bad. So they revised SQL to make it harder to do. That's the JOIN keyword. Now, when you specify additional tables you can specify how they relate at the same time. The New Way is:
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P
INNER JOIN TAG1 T ON P.Country=T.C
INNER JOIN TAG2 U ON P.Color=U.C
INNER JOIN TAG3 V ON P.Headgear=V.C
You can still use a WHERE clause, too.
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P
INNER JOIN TAG1 T ON P.Country=T.C
INNER JOIN TAG2 U ON P.Color=U.C
INNER JOIN TAG3 V ON P.Headgear=V.C
WHERE P.P=?
If you call this and pass in the value 6, you get only one row back:
Fname Lname Country Color Headgear
----- ------ ------- ------ --------
Frank Farkle Spain Orange None
As was mentioned in the comments, you are looking for an ON clause.
SELECT * FROM TEST1
INNER JOIN TEST2 ON TEST1.A = TEST2.A AND TEST1.B = TEST2.B ...
See example usage of join here:
http://en.wikibooks.org/wiki/Java_Persistence/Relationships#Join_Fetching
I am using a MS SQL db and I have 3 tables: 'base_info', 'messages', 'config'
bases:
ID Name NameNum
====================================
1 Home 101
2 Castle 102
3 Car 103
messages:
ID Signal RecBy HQ
============================
111 120 Home 1
111 110 Castle 1
111 125 Car 1
222 120 Home 2
222 125 Castle 2
222 130 Car 2
333 100 Home 1
333 110 Car 2
config:
ID SignalRec SignalOut RecBy HQ
====================================
111 60 45 101 1
111 40 60 102 1
222 50 60 102 2
222 30 90 101 2
333 80 10 103 1
Ok so now I have a subquery in which I select the 'SignalRec' and 'SignalOut' from the config table and match it on the messages table by ID and Date(not included above), the problem is that I need it to match where messages.RecBy = config.RecBy but config.RecBy is a string but it's equivalent Name is in the bases table. So I almost need to do a subquery inside a subquery or some type of join and compare the returned value.
Here is what I have so far:
(SELECT TOP 1 config.SignalRec from config WHERE config.ID = messages.ID AND ||I need th other comparison here||...Order By...) As cfgSignalRec,
(SELECT TOP 1 config.SignalOut from config WHERE config.ID = messages.ID AND ||I need th other comparison here||...Order By...) As cfgSignalOut
I tried to make this as clear as possible but if you need more info let me know.
I would normalize out RecBy in your messages table to reference the bases table. Why would you insert the string content there if it's also referenced in bases?
This is exactly why normalization exists: reduce redundancy, reduce ambiguity, and enforce referential integrity.
To make this more clear, RecBy in the messages table should be a foreign key to Bases.
I think this could do the trick (although I have not tried it...)
SELECT
c.SignalRec
FROM config c
INNER JOIN bases b
ON c.RecBy = b.NameNum
INNER JOIN messages m
ON b.Name = m.RecBy
WHERE c.ID = m.ID
However, as Anthony pointed out, you probably want to normalize out the strings in the RecBy column in the messages table, as you have the same data in the bases table.
From your description, it just sounds like you need two JOINS
SELECT TOP 1
c.SignalRec
FROM
config c
INNER JOIN
bases b
ON c.RecBy = b.NameNum
INNER JOIN
messages m
ON b.Name = m.RecBy
I think I might have not been clear enough what I wanted to do, sorry about that.
The data is actually different in the 2 tables, although the correlations are the same. It's kind of confusing to explain without going into detail about how the system works.
I actually found a very fast way of doing this.
Inside my sub-query I do this:
(SELECT TOP 1 config.Signal FROM config,bases
WHERE config.ID = messages.ID AND bases.Name = messages.RecBy AND bases.NameNum =
config.RecBy Order By...)
So this essentially compares the 2 RecBy's of different tables even though one is an integer and the other is a string. It reminds me of a match and look up in Excel.