I want to select all records from a table T1 where the values in columns A and B has no matching tuple for the columns C and D in table T2.
In mysql “Where not in” using two columns I can read how to accomplish that using the form select A,B from T1 where (A,B) not in (SELECT C,D from T2), but that fails in T-SQL for me resulting in "Incorrect syntax near ','.".
So how do I do this?
Use a correlated sub-query:
...
WHERE
NOT EXISTS (
SELECT * FROM SecondaryTable WHERE c = FirstTable.a AND d = FirstTable.b
)
Make sure there's a composite index on SecondaryTable over (c, d), unless that table does not contain many rows.
You can't do this using a WHERE IN type statement.
Instead you could LEFT JOIN to the target table (T2) and select where T2.ID is NULL.
For example
SELECT
T1.*
FROM
T1 LEFT OUTER JOIN T2
ON T1.A = T2.C AND T1.B = T2.D
WHERE
T2.PrimaryKey IS NULL
will only return rows from T1 that don't have a corresponding row in T2.
I Used it in Mysql because in Mysql there isn't "EXCLUDE" statement.
This code:
Concates fields C and D of table T2 into one new field to make it easier to compare the columns.
Concates the fields A and B of table T1 into one new field to make it easier to compare the columns.
Selects all records where the value of the new field of T1 is not equal to the value of the new field of T2.
SQL-Statement:
SELECT T1.* FROM T1
WHERE CONCAT(T1.A,'Seperator', T1.B) NOT IN
(SELECT CONCAT(T2.C,'Seperator', T2.D) FROM T2)
Here is an example of the answer that worked for me:
SELECT Count(1)
FROM LCSource as s
JOIN FileTransaction as t
ON s.TrackingNumber = t.TrackingNumber
WHERE NOT EXISTS (
SELECT * FROM LCSourceFileTransaction
WHERE [LCSourceID] = s.[LCSourceID] AND [FileTransactionID] = t.[FileTransactionID]
)
You see both columns exist in LCSourceFileTransaction, but one occurs in LCSource and one occurs in FileTransaction and LCSourceFileTransaction is a mapping table. I want to find all records where the combination of the two columns is not in the mapping table. This works great. Hope this helps someone.
Related
table1 (id, name)
table2 (id, name)
Query:
SELECT name
FROM table2
-- that are not in table1 already
SELECT t1.name
FROM table1 t1
LEFT JOIN table2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Q: What is happening here?
A: Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 with the same value for the name column. If there is no such row, we just leave the table2 portion of our result empty for that row. Then we constrain our selection by picking only those rows in the result where the matching row does not exist. Finally, We ignore all fields from our result except for the name column (the one we are sure that exists, from table1).
While it may not be the most performant method possible in all cases, it should work in basically every database engine ever that attempts to implement ANSI 92 SQL
You can either do
SELECT name
FROM table2
WHERE name NOT IN
(SELECT name
FROM table1)
or
SELECT name
FROM table2
WHERE NOT EXISTS
(SELECT *
FROM table1
WHERE table1.name = table2.name)
See this question for 3 techniques to accomplish this
I don't have enough rep points to vote up froadie's answer. But I have to disagree with the comments on Kris's answer. The following answer:
SELECT name
FROM table2
WHERE name NOT IN
(SELECT name
FROM table1)
Is FAR more efficient in practice. I don't know why, but I'm running it against 800k+ records and the difference is tremendous with the advantage given to the 2nd answer posted above. Just my $0.02.
SELECT <column_list>
FROM TABLEA a
LEFTJOIN TABLEB b
ON a.Key = b.Key
WHERE b.Key IS NULL;
https://www.cloudways.com/blog/how-to-join-two-tables-mysql/
This is pure set theory which you can achieve with the minus operation.
select id, name from table1
minus
select id, name from table2
Here's what worked best for me.
SELECT *
FROM #T1
EXCEPT
SELECT a.*
FROM #T1 a
JOIN #T2 b ON a.ID = b.ID
This was more than twice as fast as any other method I tried.
Watch out for pitfalls. If the field Name in Table1 contain Nulls you are in for surprises.
Better is:
SELECT name
FROM table2
WHERE name NOT IN
(SELECT ISNULL(name ,'')
FROM table1)
You can use EXCEPT in mssql or MINUS in oracle, they are identical according to :
http://blog.sqlauthority.com/2008/08/07/sql-server-except-clause-in-sql-server-is-similar-to-minus-clause-in-oracle/
That work sharp for me
SELECT *
FROM [dbo].[table1] t1
LEFT JOIN [dbo].[table2] t2 ON t1.[t1_ID] = t2.[t2_ID]
WHERE t2.[t2_ID] IS NULL
You can use following query structure :
SELECT t1.name FROM table1 t1 JOIN table2 t2 ON t2.fk_id != t1.id;
table1 :
id
name
1
Amit
2
Sagar
table2 :
id
fk_id
email
1
1
amit#ma.com
Output:
name
Sagar
All the above queries are incredibly slow on big tables. A change of strategy is needed. Here there is the code I used for a DB of mine, you can transliterate changing the fields and table names.
This is the strategy: you create two implicit temporary tables and make a union of them.
The first temporary table comes from a selection of all the rows of the first original table the fields of which you wanna control that are NOT present in the second original table.
The second implicit temporary table contains all the rows of the two original tables that have a match on identical values of the column/field you wanna control.
The result of the union is a table that has more than one row with the same control field value in case there is a match for that value on the two original tables (one coming from the first select, the second coming from the second select) and just one row with the control column value in case of the value of the first original table not matching any value of the second original table.
You group and count. When the count is 1 there is not match and, finally, you select just the rows with the count equal to 1.
Seems not elegant, but it is orders of magnitude faster than all the above solutions.
IMPORTANT NOTE: enable the INDEX on the columns to be checked.
SELECT name, source, id
FROM
(
SELECT name, "active_ingredients" as source, active_ingredients.id as id
FROM active_ingredients
UNION ALL
SELECT active_ingredients.name as name, "UNII_database" as source, temp_active_ingredients_aliases.id as id
FROM active_ingredients
INNER JOIN temp_active_ingredients_aliases ON temp_active_ingredients_aliases.alias_name = active_ingredients.name
) tbl
GROUP BY name
HAVING count(*) = 1
ORDER BY name
See query:
SELECT * FROM Table1 WHERE
id NOT IN (SELECT
e.id
FROM
Table1 e
INNER JOIN
Table2 s ON e.id = s.id);
Conceptually would be: Fetching the matching records in subquery and then in main query fetching the records which are not in subquery.
First define alias of table like t1 and t2.
After that get record of second table.
After that match that record using where condition:
SELECT name FROM table2 as t2
WHERE NOT EXISTS (SELECT * FROM table1 as t1 WHERE t1.name = t2.name)
I'm going to repost (since I'm not cool enough yet to comment) in the correct answer....in case anyone else thought it needed better explaining.
SELECT temp_table_1.name
FROM original_table_1 temp_table_1
LEFT JOIN original_table_2 temp_table_2 ON temp_table_2.name = temp_table_1.name
WHERE temp_table_2.name IS NULL
And I've seen syntax in FROM needing commas between table names in mySQL but in sqlLite it seemed to prefer the space.
The bottom line is when you use bad variable names it leaves questions. My variables should make more sense. And someone should explain why we need a comma or no comma.
I tried all solutions above but they did not work in my case. The following query worked for me.
SELECT NAME
FROM table_1
WHERE NAME NOT IN
(SELECT a.NAME
FROM table_1 AS a
LEFT JOIN table_2 AS b
ON a.NAME = b.NAME
WHERE any further condition);
I'm working in Access 2007 and know nothing about SQL and very, very little VBA. I am trying to do a union query to join two tables, and delete the duplicates.
BUT, a lot of my duplicates have info in one entry that's not in the other. It's not a 100% exact duplicate.
Example,
Row 1: A, B, BLANK
Row 2: A, BLANK, C
I want it to MERGE both of these to end up as one row of A, B, C.
I found a similar question on here but I don't understand the answer at all. Any help would be greatly appreciated.
I would suggest a query like this:
select
coalesce(t1.a, t2.a) as a,
coalesce(t1.b, t2.b) as b,
coalesce(t1.c, t2.c) as c
from
table1 t1
inner join table2 t2 on t1.key = t2.key
Here, I have used the keyword coalesce. This will take the first non null value in a list of values. Also note that I have used key to indicate the column that is the same between the two rows. From your example it looks like A but I cannot be sure.
If your first table has all the key values, then you can do:
select t1.a, nz(t1.b, t2.b), nz(t1.c, t2.c) as c
from table1 as t1 left join
table2 as t2
on t1.a = t2.a;
If this isn't the case, you can use this rather arcane looking construct:
select t1.a, nz(t1.b, t2.b), nz(t1.c, t2.c) as c
from table1 as t1 left join
table2 as t2
on t1.a = t2.a
union all
select t2.a, t2.b, t2.c
from table2 as t2
where not exists (select 1 from table1 as t1 where t1.key = t2.key)
The first part of the union gets the rows where there is a key value in the first table. The second gets the rows where the key value is in the second but not the first.
Note this is much harder in Access than in other (dare I say "real") databases. MS Access doesn't support common table expressions (CTEs), unions in subqueries, or full outer join -- all of which would help simplify the query.
I'm a newbie here and hoping someone can help with this sql. I've created two tables, one of which holds EVERY record, another which contains the records that I DON'T want in my table.
I tried joining them in the way I researched that is supposed to work, to include only records where they ARE NOT In the second table, but I'm getting an error.
The SQL is:
Create table t3 as
(Select * from t1
Left Outer join t2
on (t1.ID = t2.Orig_ID and t1.ID_Line = t2.Orig_ID_Line)
Where t2.Orig_ID is null
and t2.Orig_ID_Line is null)
This should be simple. However, i'm getting an error that says "Duplicate column name in Orig_ID"
HELP!
Thanks.
You were very close with your original statement, but forgot to limit the columns to those from t1, so you had twice as many columns as intended. Try:
CREATE TABLE t3 AS
(SELECT t1.* FROM t1 -- Key change * -> t1.*
LEFT OUTER JOIN t2
ON (t1.ID = t2.Orig_ID AND t1.ID_Line = t2.Orig_ID_Line)
WHERE t2.Orig_ID IS NULL
AND t2.Orig_ID_Line IS NULL)
Try this
Create table t3 as
select * from t1 where (t1.ID, t1.ID_Line) not in ( select t2.ID, t2.Orig_ID_Line from t2 where t2.ID is not null and t2.Orig_ID_Line is not null )
You get duplicate column name error, because you join and select both fields in both tables. So same column names return from the query and table can not have same column names. What you need is to select columns only in t1 table
select t1.* ......
But you do not need join operation. What you need is simple. Using "not in" operator is what you need. Have a look at an sql tutorial for in/not in operators.
I have two datasets on two seperate servers. They both pull one column of information each.
I would like to build a report showing the values of the rows that only appear in one of the datasets.
From what I have read, it seems I would like to do this on the SQL side, not the reporting side; I am not sure how to do that.
If someone could shed some light on how that is possible, I would really appreciate it.
You can use the NOT EXISTS clause to get the differences between the two tables.
SELECT
Column
FROM
DatabaseName.SchemaName.Table1
WHERE
NOT EXISTS
(
SELECT
Column
FROM
LinkedServerName.DatabaseName.SchemaName.Table2
WHERE
Table1.Column = Table2.Column --looks at equalities, and doesn't
--include them because of the
--NOT EXISTS clause
)
This will show the rows in Table1 that don't appear in Table2. You can reverse the table names to find the rows in Table2 that don't appear in Table1.
Edit: Made an edit to show what the case would be in the event of linked servers. Also, if you wanted to see all of the rows that are not shared in both tables at the same time, you can try something as in the below.
SELECT
Column, 'Table1' TableName
FROM
DatabaseName.SchemaName.Table1
WHERE
NOT EXISTS
(
SELECT
Column
FROM
LinkedServerName.DatabaseName.SchemaName.Table2
WHERE
Table1.Column = Table2.Column --looks at equalities, and doesn't
--include them because of the
--NOT EXISTS clause
)
UNION
SELECT
Column, 'Table2' TableName
FROM
LinkedServerName.DatabaseName.SchemaName.Table2
WHERE
NOT EXISTS
(
SELECT
Column
FROM
DatabaseName.SchemaName.Table1
WHERE
Table1.Column = Table2.Column
)
You can also use a left join:
select a.* from tableA a
left join tableB b
on a.PrimaryKey = b.ForeignKey
where b.ForeignKey is null
This query will return all records from tableA that do not have corresponding records in tableB.
If you want rows that appear in exactly one data set and you have a matching key on each table, then you can use a full outer join:
select *
from table1 t1 full outer join
table2 t2
on t1.key = t2.key
where t1.key is null and t2.key is not null or
t1.key is not null and t2.key is null
The where condition chooses the rows where exactly one match.
The problem with this query, though, is that you get lots of columns with nulls. One way to fix this is by going through the columns one by one in the SELECT clause.
select coalesce(t1.key, t2.key) as key, . . .
Another way to solve this problem is to use a union with a window function. This version brings together all the rows and counts the number of times that key appears:
select t.*
from (select t.*, count(*) over (partition by key) as keycnt
from ((select 'Table1' as which, t.*
from table1 t
) union all
(select 'Table2' as which, t.*
from table2 t
)
) t
) t
where keycnt = 1
This has the additional column specifying which table the value comes from. It also has an extra column, keycnt, with the value 1. If you have a composite key, you would just replace with the list of columns specifying a match between the two tables.
I want to write the following (pseudo) SQL statement in MS Access:
Select C
from MyTable
where (A, B) IN (select distinct A,B from MyTable);
I tried that but got the complaint "You have written a subquery that can return more than one field without using the EXISTS reserved word in the main query's FROM clause."
I appreciate any feedback.
You can use an inner join as a filter:
select c
from MyTable t1
inner join
(
select distinct
a
, b
from OtherTable
) t2
on t1.a = t2.a
and t1.b = t2.b
(I'm assuming you have two tables because the query doesn't make much sense for one table. Obviously, all combinations of A and B that are in Table1 will "also" be in Table1.)