I have a list of ID's, comma separated stored as string.
123,456,789
I was previously using something like this to pull data for each row in the database where each ID was present:
SELECT id, name FROM line_item WHERE id IN (123,456,789)
However, I want to only determine the ID's where they do not exist in the database. E.g. check the table to return all ID's provided that do not exist in the DB.
I tried NOT IN assuming it would work, but of course, all I got was every ID that did not match my sample, which was massive (thousands of rows, small number of ID's that we typically need to check for).
SELECT id FROM line_item WHERE id NOT IN (123,456,789)
For example:
Table: ID
111
222
333
444
555
777
999
String:
111,222,666,888,999
Query should return:
666,888
Using MySQL, can I find those values not present without using PHP.
You can create additional table populated with desired id values, and use query with LEFT JOIN and WHERE clauses -
CREATE TABLE temp_table(id INT);
INSERT INTO temp_table VALUES(123),(456),(789);
SELECT t1.id FROM temp_table t1
LEFT JOIN line_item t2
ON t1.id = t2.id
WHERE t2.id IS NULL;
Another variant:
SELECT t1.id FROM (SELECT 123 id UNION SELECT 456 UNION SELECT 789) t1
LEFT JOIN line_item t2
ON t1.id = t2.id
WHERE t2.id IS NULL;
NOT IN will take the values in the parentheses and cause the query to, as you said, give you all other ids.
I do not know if there is a way to do this with several numbers simultaneously - but this is how you could do it with one:
SELECT id, name, description
FROM line_item
WHERE 1 NOT IN (SELECT id FROM line_item) // Replace 1 with your numbers in a loop
On Postgresql you can use the generate_series(i,j) function. For example to find the non-existent integers in the id column you can write:
select i from generate_series(
(select min(id) from line_item),(select max(id) from line_item)
) as i
where i not in (select id from line_item);
If you want to use this query to find the first available integer to use as an id, you can use this query:
select min(i) from generate_series(
(select min(id) from line_item),(select max(id) from line_item)+1
) as i
where i not in (select id from line_item);
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 doing some maintenance work on a database application and I've discovered that, joy of joys, even though values from one table are being used in the style of foreign keys, there's no foreign key constraints on the tables.
I'm trying to add FK constraints on these columns, but I'm finding that, because there's already a whole load of bad data in the tables from previous errors which have been naively corrected, I need to find the rows which don't match up to the other table and then delete them.
I've found some examples of this kind of query on the web, but they all seem to provide examples rather than explanations, and I don't understand why they work.
Can someone explain to me how to construct a query which returns all the rows with no matches in another table, and what it's doing, so that I can make these queries myself, rather than coming running to SO for every table in this mess that has no FK constraints?
Here's a simple query:
SELECT t1.ID
FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.ID = t2.ID
WHERE t2.ID IS NULL
The key points are:
LEFT JOIN is used; this will return ALL rows from Table1, regardless of whether or not there is a matching row in Table2.
The WHERE t2.ID IS NULL clause; this will restrict the results returned to only those rows where the ID returned from Table2 is null - in other words there is NO record in Table2 for that particular ID from Table1. Table2.ID will be returned as NULL for all records from Table1 where the ID is not matched in Table2.
I would use EXISTS expression since it is more powerful, you can e.g. more precisely choose rows you would like to join. In the case of LEFT JOIN, you have to take everything that's in the joined table. Its efficiency is probably the same as in the case of LEFT JOIN with null constraint.
SELECT t1.ID
FROM Table1 t1
WHERE NOT EXISTS (SELECT t2.ID FROM Table2 t2 WHERE t1.ID = t2.ID)
SELECT id FROM table1 WHERE foreign_key_id_column NOT IN (SELECT id FROM table2)
Table 1 has a column that you want to add the foreign key constraint to, but the values in the foreign_key_id_column don't all match up with an id in table 2.
The initial select lists the ids from table1. These will be the rows we want to delete.
The NOT IN clause in the where statement limits the query to only rows where the value in the foreign_key_id_column is not in the list of table 2 ids.
The SELECT statement in parenthesis will get a list of all the ids that are in table 2.
Let we have the following 2 tables(salary and employee)
Now i want those records from employee table which are not in salary.
We can do this in 3 ways:
Using inner Join
select * from employee
where id not in(select e.id from employee e inner join salary s on e.id=s.id)
Using Left outer join
select * from employee e
left outer join salary s on e.id=s.id where s.id is null
Using Full Join
select * from employee e
full outer join salary s on e.id=s.id where e.id not in(select id from salary)
Where T2 is the table to which you're adding the constraint:
SELECT *
FROM T2
WHERE constrained_field NOT
IN (
SELECT DISTINCT t.constrained_field
FROM T2
INNER JOIN T1 t
USING ( constrained_field )
)
And delete the results.
From similar question here MySQL Inner Join Query To Get Records Not Present in Other Table I got this to work
SELECT * FROM bigtable
LEFT JOIN smalltable ON bigtable.id = smalltable.id
WHERE smalltable.id IS NULL
smalltable is where you have missing records, bigtable is where you have all the records. The query list all the records that not exist in smalltable but exists on the bigtable. You could replace id by any other matching criteria.
I Dont Knew Which one Is Optimized (compared to #AdaTheDev
) but This one seems to be quicker when I use (atleast for me)
SELECT id FROM table_1 EXCEPT SELECT DISTINCT (table1_id) table1_id FROM table_2
If You want to get any other specific attribute you can use:
SELECT COUNT(*) FROM table_1 where id in (SELECT id FROM table_1 EXCEPT SELECT DISTINCT (table1_id) table1_id FROM table_2);
You could opt for Views as shown below:
CREATE VIEW AuthorizedUserProjectView AS select t1.username as username, t1.email as useremail, p.id as projectid,
(select m.role from userproject m where m.projectid = p.id and m.userid = t1.id) as role
FROM authorizeduser as t1, project as p
and then work on the view for selecting or updating:
select * from AuthorizedUserProjectView where projectid = 49
which yields the result as shown in the picture below i.e. for non-matching column null has been filled in.
[Result of select on the view][1]
You can do something like this
SELECT IFNULL(`price`.`fPrice`,100) as fPrice,product.ProductId,ProductName
FROM `products` left join `price` ON
price.ProductId=product.ProductId AND (GeoFancingId=1 OR GeoFancingId
IS NULL) WHERE Status="Active" AND Delete="No"
SELECT * FROM First_table
MINUS
SELECT * FROM another
How to select rows with no matching entry in Both table?
select * from [dbo].[EmppDetails] e
right join [Employee].[Gender] d on e.Gid=d.Gid
where e.Gid is Null
union
select * from [dbo].[EmppDetails] e
left join [Employee].[Gender] d on e.Gid=d.Gid
where d.Gid is Null
i have two tables in a DB with the following structure:
table 1: 3 rows - category_id, product_id and position
table 2: 3 rows - category_id, product_id and position
i am trying to set table 1 position to table 2 position where category and product id is the same from the tables.
below is the sql i have tried to make this happen but returns MySQL error 1242 - subquery returns more then 1 row
UPDATE table1
SET position = (
SELECT position
FROM table2
WHERE table1.product_id = table2.product_id AND table1.category_id = table2.category_id
)
The solution is very simple and it can be done in two simple steps. The first step is just a preview of what will be changed, to avoid destroying data. It can be skipped if you are confident of your WHERE clause.
Step 1: preview the changes
Join the tables using the fields you want to match, select everything for visual validation of the match.
SELECT t1.*, t2.*
FROM table1 t1
INNER JOIN table2 t2
ON t1.category_id = t2.category_id
AND t1.product_id = t2.product_id
You can also add a WHERE clause if only some of the rows must be modified.
Step2: do the actual update
Replace the SELECT clause and the FROM keyword with UPDATE, add the SET clause where it belongs. Keep the WHERE clause:
UPDATE table1 t1
INNER JOIN table2 t2
ON t1.category_id = t2.category_id
AND t1.product_id = t2.product_id
SET t1.position = t2.position
That's all.
Technical considerations
Indexes on the columns used on the JOIN clause on both tables are a must when the tables have more than several hundred rows. If the query doesn't have WHERE conditions then MySQL will use indexes only for the biggest table. Indexes on the fields used on the WHERE condition will speed up the query. Prepend EXPLAIN to the SELECT query to check the execution plan and decide what indexes do you need.
You can add SORT BY and LIMIT to further reduce the set of changed rows using criteria that cannot be achieved using WHERE (for example, only the most recent/oldest 100 rows etc). Put them on the SELECT query first to validate the outcome then morph the SELECT into an UPDATE as described.
Of course, indexes on the columns used on the SORT BY clause are a must.
You can run this query to see what is happening:
SELECT product_id, category_id, count(*), min(position), max(position)
FROM table2
GROUP BY product_id, category_id
HAVING COUNT(*) > 1;
This will give you the list of product_id, category_id pairs that appear multiple times in table2. Then you can decide what to do. Do you want an arbitrary value of position? Is the value of position always the same? Do you need to fix the table?
It is easy enough to fix the particular problem by using limit 1 or an aggregation function. However, you may really need to fix the data in the table. A fix looks like:
UPDATE table1 t1
SET t1.position = (SELECT t2.position
FROM table2 t2
WHERE t2.product_id = t1.product_id AND t2.category_id = t1.category_id
LIMIT 1
);
i have spent the last 2 days going over this problem trying to work it out.
i have two tables
one is the user_login and it has a row called user_id the other is agedcare and it has a row called id
i have tried to get the 2 to link together
i want to be able to update the agedcare using the id from user_login as the main id
$query = "SELECT id FROM agedcare INNER JOIN user_id ON login_users = login_users.user_id WHERE login_users.user_id = '$id'"
The format is something more like..
SELECT id,name,age
FROM Table1
INNER JOIN Table2
ON Table1.Field=Table2.Field
Another way to simplify the select statement (so that you avoid using the table names throughout) is to "rename" the table right after you name it. For example, the line that has "FROM Table1 T1" - the T1 immediately after the table name is "renaming" the table allowing you to shorten the table name when you need to refer to it. In addition, you can use the t1 and t2 identifiers when selecting the fields.
SELECT t1.id,t1.name,t2.age
FROM Table1 T1
INNER JOIN Table2 T2
ON T1.Field=T2.Field
Check your format of join, it must be like this
SELECT * FROM t1 as a LEFT JOIN t2 as b ON a.id=b.id where user_id = 'id'
I have 2 tables,
Table1: id,int1,int2,int3,int4,int5
Table2: integers (autoincrement),blobdata
The query I want to use is given the id I want to get the blobdata from table2 associated with the 5 integers in table1. I've only ever used one table in mysql so have no idea how to do this properly.
Is it possible?
EDIT: id is username, integers in table2 is just integers. but have not built the tables yet, so can change if need to.
select t1.id, t1.int1, t1.int2 ... t2.blobdata
from table1 t1, table2 t2
where t1.id = t2.id and t1.id = <your input id>
Assuming the auto increment integer column is the id that match the id on table1.
t2.id - or any other name you will call this column of course.
What you need is to set a foreign key in table1, which would contain the id of the blobdata you want to point to.
Take a look here: http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html