Is it possible to have an "IN" statement within a left join clause?
I have two tables with two columns:
Table 1: Table 2:
Column1: Column2:
192192, 192192
119202 119202
810395 810395
975643, 975643
908574,, 908574
As you can see, tbl1.col1 has entries can have entries with commas trailing or have none at all. I need to join the two tables where column 1 contains column 2 or where they are equal. It made sense to be to join where column1 includes column 2. Maybe there's a better way to accomplish the join?
I need to join the two to access data in table 2. So the columns just need to align while allowing for a potential comma or two in column 1. Any suggestions?
If this is just some sort of one-time deal or a staging table and not your real prod table:
(this one works no matter where inteh number the commas are)
select <column list>
from table1 t1
join table2 t2 on replace(t1.col1, ',','') = t2.col2
or
select <column list>
from table1 t1
join table2 t2 on cast(t2.col2 as varchar (10)) like t1.col1+'%'
(you may or may not need the cast depending onthe data types of the tow columns, I was assuming one was varchar and the other was integer)
or
(this only works if the value will always be the same length
select <column list>
from table1 t1
join table2 t2 on left(t1.col1,6) = t2.col2
If this is a real prod table, then you could have performance issues joining on a function, so fix the data instead.
I think rtrim() is perfect for this:
SELECT *
FROM table1 t1
JOIN table2 t2 ON trim(t1.col1, ',') = t2.col2;
Also you may just want to substr function to trim the first table column and use the left outer join as:
using substr:
select t1.col1, t2.col2
from table1 t1 left join table2 t2
on substr(t1.col1, 0, length(t1.col1)-1) = t2.col2;
using replace:
select t1.col1, t2.col2
from table1 t1 left join table2 t2
on replace(t1.col1, ',' , '')= t2.col2;
Both the above queries should work in MySQL and Oracle.
Related
I used this code in SQL Server to join two tables on unique values i made with concat.
My intention was to create unique values with concat function in both tables so I can join them on matching values.
Problem is that query written in this way never never executes (like some sort of infinite loop)
[Table inputs and result]
select t1.AAA, t1.BBB, t1.XXX, t2.YYY
from Table1 t1
inner join Table2 t2
on concat(t1.AAA, t1.BBB)= CONCAT(t2.AAA, t2.BBB)
why concat , this way you lose benefit of optimizer & index ,
you can join on two condition :
select select t1.AAA, t1.BBB, t1.XXX, t2.YYY
from Table1 t1
inner join Table2 t2
on t1.AAA= t2.AAA
and t1.BBB = t2.BBB
The query that you want is:
select t1.AAA, t1.BBB, t1.XXX, t2.YYY
from Table1 t1 inner join
Table2 t2
on t1.AAA = t2.AAA and t1.BBB = t2.BBB;
Then, if performance is a concern, you want an index on Table1(AAA, BBB) or Table2(AAA, BBB) or both. The columns can also be reversed in the indexes.
I want to join two tables in Access based on different wildcards for different rows.
The first, table1, contains rows with different wildcards and table2 contains the column that should be matched with the wildcards in table1.
I imagine the SQL code to look like:
SELECT *
FROM table2
LEFT JOIN table1
ON table2.subject LIKE table1.wildcard
The tables look like this: https://imgur.com/a/O9OPAL6
The third pictures shows the result that I want.
How do I execute the join or is there an alternative?
I don't think MySQL support non-equality conditions for JOINs. So, you can do this as:
SELECT * -- first get the matches
FROM table2 as t2, -- ugg, why doesn't it support CROSS JOIN
table1 as t1
WHERE t2.subject LIKE t1.wildcard
UNION ALL
SELECT * -- then get the non-matches
FROM table2 as t2 LEFT JOIN
table1 as t1
ON 1 = 0 -- always false but gets the same columns
WHERE NOT EXISTS (SELECT 1
FROM table1 as t1
WHERE t2.subject LIKE t1.wildcard
);
I have a query that I'm trying to rework that has over 1,000 columns when I select * FROM several tables. I want to know if there is a way in SQL to tag the column alias with the table alias so i can know from which table the columns are from. It looks like the following:
SELECT *
FROM table1 t1
join table2 t2
join table3 t3
join table4 t4
Current column output:
id, id, id, id, name, name, name, name, order, order, order, order
Desired Column output:
t1.id, t1.name, t1.order, t2.id, t2.name, t2.order,t3.id, t3.name, t3.order, t4.id, t4.name, t4.order
this is a very simple example but you can imagine trying to fish out the column you need of a sea of 1,000 columns trying to figure out what table it came from! Any ideas??
I'm not aware of a way to prefix each column with the column alias. However I do know how you could easily break the columns into groups that would allow you to figure out which table each column comes from.
SELECT 'T1' as [Table1]
, t1.*
, 'T2' as [Table2]
, t2.*
, 'T3' as [Table3]
, t3.*
, t4.* as [Table4]
, t4.*
, 'T5' as [Table5]
, t5.*
FROM table1 t1
join table2 t2
join table3 t3
join table4 t4
This would break out the columns into groups by table and it would break a little bookmark before and after each group to help you understand where they're coming.
I know not exactly what you asked for but I believe it would help you a lot in figuring out what's from what tables.
Your other option is as others have said and specifiying the prefix on every column which it sounds like you don't want to do. However it can be a lot quicker to do this if you drag the columns from the Object Explorer - and use ALT-SHIFT to add the prefix to each column.
Here's an article about copying columns from object explorer - https://www.qumio.com/Blog/Lists/Posts/Post.aspx?ID=56
Her's an article about adjusting code using ALT+SHIFT - https://blogs.msdn.microsoft.com/sql_pfe_blog/2017/04/11/quick-tip-shiftalt-for-multiple-line-edits/
The first method would take less than a method, the 2nd method I could see taking less than 10 minutes even for 1,000 columns.
You have to assign non-default column aliases manually:
select t1.id as t1_id, t1.name as t1_name, t1.order as t1_order,
t2.id as t2_id, t2.name as t2_name, t2.order as t2_order,
. . .
You might find that a spreadsheet or query can help, if you have a lot of columns.
Some products may have exceptions, but generally no, you can't do that. You either have to use wildcards (SELECT *) or specify the columns you wish returned by full and complete name.
If you specify columns, you can "alias" them, set the column name to something other than the source name. For example (psuedo-code, leaving out the "ON" clause):
SELECT
T1.Id as T1_Id
,T2.Id as T2_Id
from table1 T1
join table2 T2
Note that you can combine table aliases with wildcards. For example:
SELECT
T2.*
from table1 T1
join table2 T2
join table3 T3
join table4 T5
will return all the columns from table2, and only from table2. This might help in revising your query by getting a list of the available columns in each table.
I am trying to write an SQL query that will return Table1, which has 10 columns. This table consists of a primary key id, 4 foreign key Id columns, and 5 other columns that I want to return but not change. The goal is to do a join to replace the foreign key Ids with their descriptions that are held in other tables.
Here is one attempt with the first FK Id:
Select * from Table1 t1
left join Table2 t2
on t1.BranchId = t2.BranchId;
This left join returns the description from table2, but does not replace it.
Here is another with the first FK Id:
Select t2.BranchName from Table1 t1
left join Table2 t2
on t1.BranchId = t2.BranchId;
This returns the name I want, but does not return table1 fully.
For the sake of an example you could pretend that OtherName3, OtherName4, OtherName5 are in tables Table3, Table4, Table5, respectively.
This may seem trivial for experienced SQL devs, but I am having a hard time figuring out the syntax.
Thanks!
I'm not sure what you mean by replace it.
I think you just need to list out all the columns you want:
Select t1.col1, t1.col2, t1.col3, . . .,
t2.name
from Table1 t1 left join
Table2 t2
on t1.BranchId = t2.BranchId;
I don't know what you mean by 'replace' but you just need to qualify what columns from which table you want. That goes for all tables you are joined to, especially if they have the same column name in multiple tables. I put junk columns in since I don't know your tables but you should get the general idea.
Select t2.BranchName, t1.BranchId, t1.Name, t1.Amount, t2.BranchLocation from Table1 t1
left join Table2 t2
on t1.BranchId = t2.BranchId;
I think this is what you are looking for:
select t1.*, t2.BranchName from Table1 t1
left join Table2 t2
on t1.BranchId = t2.BranchId;
Return Table1 fully (all columns) and only the description (BranchName) from Table2.
If using SQL Server, see all syntax options for the SELECT clause here:
https://msdn.microsoft.com/en-us/library/ms176104.aspx
I am a little confused as to how to approach this SQL query.
I have two tables (equal number of records), and I would like to return a column with which is the division between the two.
In other words, here is my not-working-correctly query:
SELECT( (SELECT v FROM Table1) / (SELECT DotProduct FROM Table2) );
How would I do this? All I want it a column where each row equals the same row in Table1 divided by the same row in Table2. The resulting table should have the same number of rows, but I am getting something with a lot more rows than the original two tables.
I am at a complete loss. Any advice?
It sounds like you have some kind of key between the two tables. You need an Inner Join:
select t1.v / t2.DotProduct
from Table1 as t1
inner join Table2 as t2
on t1.ForeignKey = t2.PrimaryKey
Should work. Just make sure you watch out for division by zero errors.
You didn't specify the full table structure so I will assume a common ID column to link rows in the tables.
SELECT table1.v/table2.DotProduct
FROM Table1 INNER JOIN Table2
ON (Table1.ID=Table2.ID)
You need to do a JOIN on the tables and divide the columns you want.
SELECT (Table1.v / Table2.DotProduct) FROM Table1 JOIN Table2 ON something
You need to substitue something to tell SQL how to match up the rows:
Something like: Table1.id = Table2.id
In case your fileds are both integers you need to do this to avoid integer math:
select t1.v / (t2.DotProduct*1.00)
from Table1 as t1
inner join Table2 as t2
on t1.ForeignKey = t2.PrimaryKey
If you have multiple values in table2 relating to values in table1 you need to specify which to use -here I chose the largest one.
select t1.v / (max(t2.DotProduct)*1.00)
from Table1 as t1
inner join Table2 as t2
on t1.ForeignKey = t2.PrimaryKey
Group By t1.v