I want an SQL code which should perform the task of data scrubbing.
I have two tables both contain some names I want to compare them and list out only those name which are in table 2 but not in table 1.
Example:
Table 1 = A ,B,C
Table 2 = C,D,E
The result must have D and E?
SELECT t2.name
FROM 2 t2
LEFT JOIN
1 t1 ON t1.name=t2.name
WHERE t1.name IS NULL
select T2.Name
from Table2 as T2
where not exists (select * from Table1 as T1 where T1.Name = T2.Name)
See this article about performance of different implementations of anti-join (for SQL Server).
select t2.name
from t2,t1
where t2.name<>t1.name -- ( or t2.name!=t1.name)
If the DBMS supports it:
select name from table2
minus
select name from table1
A more portable solution could also be:
select name from table2
where name not in (select name from table1)
Related
So, I have a table with the following structure:
id
columnA
columnB
1
Yes
1
No
I want to combine the row into a single row, so it ends up like this:
id
columnA
columnB
1
Yes
No
I believe a self join here would work like this:
SELECT t1.columnA , t2.columnB
FROM table1 t1, table1 t2
where t1.id = t2.id
But is there a way to do this without specifying the columns? I have a table that has 100 columns and I'm trying to see if I can accomplish this without listing out all the columns.
Use the below query to get the column name with aggregation (Query created using information schema to get the column names). Write a select using the result and run the query.
select
case when column_name='Id' then column_name
else concat(',Max(', column_name,')') end as Name
from information_schema.columns
where table_name = 'Table1';
You will get something like below as output, where A and B are the column names.
Id
,Max(A)
,Max(B)
Add convert the result to query
Select
Id
,Max(A)
,Max(B)
from Table1 Group by Id
is there a way to do this without specifying the columns?
You can use using to answer your question.
SELECT t1.columnA , t2.columnB
FROM table1 t1 JOIN
table1 t2
USING (id);
To get the data you want, use aggregation:
SELECT id, MAX(t1.columnA), MAX(t2.columnB)
FROM table1 t1
GROUP BY id;
Use your JOIN only change the colums for *
SELECT t1.*, t2.*
FROM table1 t1, table1 t2
where t1.id = t2.id
I have two tables and I need to fetch if any one ID is not present in the table 2. I tried the query but its not giving the correct result. Kindly suggest.
TABLE 1
TABLE 2
Output Should be: Because Release ID and purchase ID is not present in both the columns.
QUERY Tried :
SELECT T1_ID
FROM T1 LEFT OUTER JOIN T2
ON t1.RELEASEID=t2.RELEASEID
LEFT OUTER JOIN T2 t3
ON t1.PURCHASEID=t3.PURCHASEID
WHERE IFNULL(T2.RELEASEID,'') ='' OR IFNULL(T3.PURCHASEID,'')=''
You can use NOT EXISTS as follows:
select * from t1
where not exists (select 1 from t2
where t1.releaseid =t2.releaseid or t1.purchaseid =t2.purchaseid)
You can also use LEFT JOIN as follows:
select t1.*
from t1 left join t2
on t1.releaseid =t2.releaseid or t1.purchaseid =t2.purchaseid
where t2.t2_id is null
One method is not exists:
select t1.*
from t1
where not exists (select 1
from t2
where t2.releaseid = t1.releaseid
) and
not exists (select 1
from t2
where t2.purchaseid = t1.purchaseid
);
This should work regardless of whether ? is really a string or is supposed to represent NULL.
Note: This can take advantage of indexes on t2(releaseid) and t2(purchaseid), which can be a big boost to performance on larger data.
I think you want:
select t1.*
from table1 t1
where
(t1.release_id = '?' and t2.purchase_id = '?')
or not exists (
select 1
from table2 t2
where t1.release_id in ('?', t2.release_id)
and t1.purchase_id in ('?', t2.purchase_id)
)
If the question mark is supposed to represent null values, you can just replace all instances of = '?' with is null.
Please try this and let me know if it works.
SELECT * FROM TABLE1 WHERE NOT EXISTS (SELECT '1' FROM TABLE2 WHERE TABLE1 .RELEASEID=TABLE2.RELEASEID OR TABLE1 .PURCHASEID=TABLE2.PURCHASEID);
I have two tables:
Table 1 with columns Number and TEXT
Table 2 with columns Number and TEXT
Now Table 1 has Nr = 12345AB and Table 2 Nr = 00012345AB
How can I find all columns from Table 1 that are not in Table 2?
Try this select:
select
*
from
table1 t1
left join table2 t2 on t1.number=t2.number
where
t2.number is null
Try exists:
select t1.*
from Table1 t1
where not exists (select 1
from Table2 t2
where t2.Number = t1.Number)
I think he is looking for a fuzzy match. In which case =, LIKE, CONTAINS will not work. You will need to roll your own similar to this solution.
This is also a method but its too lengthy :-)
SELECT table1.*
FROM table2
WHERE (number NOT IN
(SELECT number
FROM table2)) AND (text NOT IN
(SELECT text
FROM table2))
I have two tables with the same structure:
id name
1 Merry
2 Mike
and
id name
1 Mike
2 Alis
I need to union second table to first with keeping unique names, so that result is:
id name
1 Merry
2 Mike
3 Alis
Is it possible to do this with MySQL query, without using php script?
This is not a join (set multiplication), this is a union (set addition).
SELECT #r := #r + 1 AS id, name
FROM (
SELECT #r := 0
) vars,
(
SELECT name
FROM table1
UNION
SELECT name
FROM table2
) q
This will select all names from table1 and combine those with all the names from table2 which are not in table1.
(
select *
from table1
)
union
(
select *
from table2 t2
left join table1 t1 on t2.name = t1.name
where t1.id is null
)
Use:
SELECT a.id,
a.name
FROM TABLE_A a
UNION
SELECT b.id,
b.name
FROM TABLE_B b
UNION will remove duplicates.
As commented, it all depends on what your 'id' means, cause in the example, it means nothing.
SELECT DISTINCT(name) FROM t1 JOIN t2 ON something
if you only want the names
SELECT SUM(something), name FROM t1 JOIN t2 ON something GROUP BY name
if you want to do some group by
SELECT DISTINCT(name) FROM t1 JOIN t2 ON t1.id = t2.id
if the id's are the same
SELECT DISTINCT COALESCE(t1.name,t2.name) FROM
mytable t1 LEFT JOIN mytable t2 ON (t1.name=t2.name);
will get you a list of unique names from the 2 tables. If you want them to get new ids (like Alis does in your desired results), that's something else and requires the answers to a couple of questions:
do any of the names need to maintain their previous id. And if they do, which table's id should be preferred?
why do you have 2 tables with the same structure? ie what are you trying to accomplish when you generate the unique name list?
hi i am using SQL Server 2008, want to create a view to list the different between two tables.
for example
t1
id name
---- ------
1 John
2 peter
3 mary
4 joe
5 sun
t2
id name
--- ----
1 john
2 joe
how to create a view to list all the name in t1 but not in t2.
i tried to do that, and always get
"Conversion failed when converting from a character string to uniqueidentifier."
error
and also, i don`t want to use
select something not in {something}, this is slow
so is there any way can use join??
NOT IN
SELECT t1.name
FROM TABLE_1 t1
WHERE t1.name NOT IN (SELECT t2.name
FROM TABLE_2 t2)
NOT EXISTS
SELECT t1.name
FROM TABLE_1 t1
WHERE NOT EXISTS (SELECT NULL
FROM TABLE_2 t2
WHERE t2.name = t1.name)
LEFT JOIN/IS NULL:
SELECT t1.name
FROM TABLE_1 t1
LEFT JOIN TABLE_2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Summary
Contrary to your belief, NOT IN will perform equivalent to NOT EXISTS. LEFT JOIN/IS NULL is the least efficient of the three options.
Here's a trick I use:
SELECT MAX(TABLE_NAME) AS TABLE_NAME
,[id]
,[name]
FROM (
SELECT 'T1' AS TABLE_NAME
,[id]
,[name]
FROM T1
UNION ALL
SELECT 'T2' AS TABLE_NAME
,[id]
,[name]
FROM T2
) AS X
GROUP BY [id]
,[name]
HAVING COUNT(*) = 1
ORDER BY [id]
,[name]
I actually have a universal proc I use which takes two tables and a bunch of parameters and does table compares generating dynamic SQL (the SQL above is actually cleaned up code-generated output of it), it uses either this UNION ALL trick or a combination of the three joins in OMG Ponies' answer depending on whether key columns/ignore columns/comare columns are specified.
SELECT name FROM TABLE_1
EXCEPT
SELECT name FROM TABLE_2