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 fairly new to SQL and have been trying to figure this one out for a while.
I have tableA with Club_Name, Image_Path,... and then I have tableB with Club_Name, Article,...
I am exporting tableB to a JSON array and need to include Image_Path, how can I best do this? If I ad an Image_Path column to tableB is there a means to conditionally populate it based on Club_Name and a lookup to tableA?
You need to join the 2 tables together, based on a column value that exists in both tables.. ..in your case: 'Club_Name'
SELECT a.Club_Name, a.Image_Path, b.Article
FROM tableA a
JOIN tableB b USING (Club_Name)
I have written a query to fetch details from table1, which has this condition clause:
IN(number1,number2......
Up to 323 entries so far now. These numbers are the primary key of table1, which has been extracted from table2 and passed into the IN condition clause.
Due to this my query slows down and takes 13 seconds to run. Is there any other way to overcome this? If I give some constant values (like PK id), the query works in usual time.
You can also do it using LEFT JOIN:
For example:
SELECT T1.*
FROM Table1 T1 LEFT JOIN
Table2 T2 ON T1.numberfield = T2.numberfield
WHERE T2.someotherfield IS NOT NULL
This does the exact job of the query with IN.
try below-
select a.* from table1 a join table2 b
on a.parent_id=b.id;
Note: parent_id should be indexed in table 1 and assuming id will be prmary key of table b means already indexed.
I use php and mysql. I have two tables,
table A (Id: auto-increment , idno)
table B (Id:auto-increment, sidno).
Table A contains about 3000 records and Table B contains about 27000 records. I want to search whether each of the records in table A exist in table B, if not print the records that does not exist in table B.
I tried to retrieve the records in table A and checking them against table A, but I could not succeed. And it took a very long time to finished the query.
And I have searched throughout but could not get something like this.
Please can anybody help me.
Thanks!
The following query might return all the idno which are not in table B
SELECT * FROM tableA WHERE `idno` NOT IN (SELECT `sidno` FROM tableB)
SQL Fiddle Demo
Ok. Try this:
SELECT tableB.Id, tableB.sidno
FROM tableA
RIGHT JOIN tableB ON tableA.Id = tableB.ID
WHERE tableA.Id = 'NULL';
This should give you all the records you want.
like this
select * from tableA where Minus select id from where tableA.id=tableB.id;
MINUS
http://www.techonthenet.com/sql/minus.php
Try this
SELECT * FROM table2 t where sid NOT IN (select id from table1) ;
Demo
I have 2 tables table1 and table2, where table1 contains the data collected so far, and table2 contains table1's data along with some updated/additional data. I need to retrieve only this updated/additional data and insert it into table1.
Now I know I can use NOT IN to do this, but I am not sure it will be a very efficient solution in case of a huge number of records. Any suggestion on what the best approach would be in terms of execution speed?
This can be done with simple join both tables
something like below:
select t1.* from table1 as t1 join table2 as t2 on t1.id=t2.id where ...[]
I'm not sure if i've understand your question correctly but let me give it a try. Suppose you have a design like this:
TableA : {colA, colB, colC, colD, colE}
TableB : {colA, colB, RecC, RecD, RecE}
where Tables (tableA, tableB) is joined on ColA. I Assumed that TableA's columns (colC, ColD, colE) will be updated and the records are based on TableB's columns (recC, recD, recE).
In your statement: I need to retrieve only this updated/additional data and insert it into table1.. I think you want to update TableA's records based on TableB
UPDATE TableA a INNER JOIN TableB b ON a.ColA = b.ColA
SET a.ColC = b.RecC,
a.ColD = b.RecD,
a.ColE = b.RecE
-- WHERE (Condition) -- if you want to have a condition.
so the statement above updates all the records in tableA if colA also exist in tableB since I've used INNER JOIN. You could also use LEFT JOIN.