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I am working in SQL Server 2008. I have 2 tables Table1 & Table2.
Table1 has columns
SchoolCode, District, Type, SchoolName
and Table2 has columns
SchoolCode1, District1, Type1, SchoolName1
SchoolCode columns in both tables have the same codes like "1234"; code is the same in both schoolcode columns.
Now I want to copy the District, Type and SchoolName column values from Table1 to Table2 if SchoolCode in both tables is same.
I think the query will use join but I don't know how it works. Any help on how I can do this task?
Maybe use an update statement in join if by copying over you mean updating rows
update t2
set
District1= District,
Type1= Type,
SchoolName1= SchoolName
from Table1 t1
join
Table2 t2
on t1.SchoolCode=t2.SchoolCode1
I could give you a little bit of idea. here is it:
Insert into table2 (District1, Type1, SchoolName1)
SELECT District, Type, SchoolName
FROM table1
where table1.Schoolcode=table2.Schoolcode1
You have to use Inner join to update data from table 1 to table 2, Inner join will join values that are equal. . To learn more about joins, I highly recommend you to read the below article
SQLServer Joins Explained - W3Schools
Please refer the below code, for the convenience I have used the temporary tables..
DECLARE #Table1 TABLE
(
SchoolCode INT,
District VARCHAR(MAX),
Type VARCHAR(MAX),
SchoolName VARCHAR(MAX)
)
DECLARE #Table2 TABLE
(
SchoolCode1 INT,
District1 VARCHAR(MAX),
Type1 VARCHAR(MAX),
SchoolName1 VARCHAR(MAX)
)
INSERT INTO #Table1
( SchoolCode ,District , Type , SchoolName
)
VALUES ( 1 ,'DIS1' ,'X' ,'A'),
( 2 ,'DIS2' ,'Y' ,'B'),
( 3 ,'DIS3' ,'Z' ,'C'),
( 4 ,'DIS4' ,'D' ,'D'),
( 5 ,'DIS5' ,'K' ,'E')
INSERT INTO #Table2
( SchoolCode1 ,District1 , Type1 , SchoolName1
)
VALUES ( 1 ,'DIS1' ,'X' ,'A'),
( 2 ,NULL ,'Z' ,NULL),
( 3 ,'DIS3' ,'Z' ,'C'),
( 4 ,NULL ,'Z' ,'S'),
( 5 ,'DIS5' ,'K' ,'E')
--BEFORE
SELECT * FROM #Table1
SELECT * FROM #Table2
--Logic UPDATE Table 2
UPDATE t2 SET t2.District1 = t1.District,
t2.Type1 = t1.Type,
t2.SchoolName1 = t1.SchoolName
FROM #Table1 t1
INNER JOIN #Table2 t2 ON t1.SchoolCode = t2.SchoolCode1
-- End Logic UPDATE Table 2
--AFTER
SELECT * FROM #Table1
SELECT * FROM #Table2
You can join tables in an UPDATE statement.
Note, I have aliased the tables, table1 and table2 as t1 and t2 respectively.
This is what I did:
create table Table1
(SchoolCode varchar(50),
District varchar(50),[Type] varchar(50),SchoolName varchar(50))
go
create table Table2
(SchoolCode1 varchar(50), District1 varchar(50),[Type1] varchar(50),SchoolName1 varchar(50))
go
insert into table1 values ('1234','District1','High','Cool School')
insert into table1 values ('2222','District2','Lower','Leafy School')
insert into table2 (SchoolCode1) values ('1234')
go
update t2
set District1 = District,
Type1 = [Type],
SchoolName1 = SchoolName
from table1 t1
join table2 t2
on t2.SchoolCode1 = t1.SchoolCode
go
select * from table2
go
From doing a bit of research it seems it’s not possible to do an insert with a where clause?
I have a table I want to import into another table where specific record criteria doesn’t already exist. How would I go about this ?
E.g pseudo code -
insert into table b (select * from table a) where not exists tableb.column1 = tablea.column1 and tableb.column2 = tablea.column2
Could this potentially be done with a Join ?
You can insert using INSERT INTO.. SELECT with NOT EXISTS.
Query
insert into [TableB]
select * from [TableA] as [t1] -- [TableA] and [TableB] structure should be same.
where not exists(
select 1 from [TableB] as [t2]
where [t1].[column1] = [t2].[column1]
and [t1].[column2] = [t2].[column2]
);
Or, if the table structure is not same and need to same few columns, then
Query
insert into [TableB]([column1], [column2], ..., [columnN])
select [column1], [column2], ..., [columnN]
from [TableA] as [t1]
where not exists(
select 1 from [TableB] as [t2]
where [t1].[column1] = [t2].[column1]
and [t1].[column2] = [t2].[column2]
);
You can also use LEFT JOIN with IS NULL as below:
INSERT INTO tableb
SELECT a.*
FROM tablea a
LEFT JOIN tableb b ON b.column1 = a.column1
AND b.column2 = a.column2
WHERE b.column1 IS NULL
Referencing table name from INSERT statement in SELECT part will not work, because INSERT is not a query itself, but nothing prevents to query destination table in SELECT, which produces the data set to be inserted.
INSERT INTO tableb (column1, column2)
SELECT column1, column2 FROM tablea
WHERE NOT EXISTS (SELECT * FROM tableb
WHERE tableb.column1 = tablea.column1
AND tabled.column2 = tablea.column2)
Try this :
Via Insert with Select statement with Not Exists
Declare #table1 table(Id int , EmpName varchar(100) )
Declare #table2 table(Id int , EmpName varchar(100) )
Insert into #table1 values (1,'Ajay'), (2, 'Tarak') , (3,'Nirav')
Insert into #table2 values (1,'Ajay')
--Insert into table b (select * from table a) where not exists tableb.column1 = tablea.column1 and tabled.column2 = tablea.column2
INSERT INTO #table2 (id, empname)
select id, empname from #table1
EXCEPT
SELECT id, empname from #table2
Select * from #table1
Select * from #table2
Via merge
Insert into #table2 values (4,'Prakash')
Select * from #table1
Select * from #table2
Declare #Id int , #EmpName varchar(100)
;with data as (select #id as id, #empname as empname from #table1)
merge #table2 t
using data s
on s.id = t.id
and s.empname = t.empname
when not matched by target
then insert (id, empname) values (s.id, s.empname);
Select * from #table1
Select * from #table2
I want to delete from t2 if same value of itemid,storeid,MSRTime does not exist on t1 and Same value of itemid,storeid,MSRTime exist on t3 and status is D. In below example i should be able to delete second row on t2 but not 1st row.
Table 1: t1
itemid |storeid|MSRTime
x y z
Table 2: t2
itemid |storeid|MSRTime
x y z
a b c
Table 3: t3
itemid |storeid|MSRTime|status
x y z D
a b c D
I tried doing this using join but i could not reach the desired result. Please help.
Thank You.
You can write the query almost exactly as you've described it:
declare #t1 table(itemid varchar(7),storeid varchar(9),MSRTime varchar(3))
insert into #t1(itemid,storeid,MSRTime) values
('x','y','z')
declare #t2 table(itemid varchar(7),storeid varchar(9),MSRTime varchar(3))
insert into #t2(itemid,storeid,MSRTime) values
('x','y','z'),
('a','b','c')
declare #t3 table(itemid varchar(7),storeid varchar(9),MSRTime varchar(3),status varchar(4))
insert into #t3(itemid,storeid,MSRTime,status) values
('x','y','z','D'),
('a','b','c','D')
delete from t2
from #t2 t2
inner join
#t3 t3
on
t2.itemid = t3.itemid and
t2.storeid = t3.storeid and
t2.MSRTime = t3.MSRTime and
t3.status = 'D'
where
not exists (
select *
from #t1 t1
where t1.itemid = t2.itemid and
t1.storeid = t2.storeid and
t1.MSRTime = t2.MSRTime
)
select * from #t2
Result:
itemid storeid MSRTime
------- --------- -------
x y z
Should be something like this
-- delete t2
select *
from table2 t2
JOIN table3 t3 on t2.itemid = t3.itemid and
t2.storeid = t3.storeid and
t2.MSRTime = t3.MSRTime
LEFT JOIN table1 t1 on t2.itemid = t1.itemid and
t2.storeid = t1.storeid and
t2.MSRTime = t1.MSRTime
where t1.itemID IS NULL
Run the select first, if it gives you back right row, just un-comment delete and you are good to go
I have created the whole script for your reference. Please use the last DELETE query for your scenario. That will do the trick.
CREATE TABLE #T1
(itemid VARCHAR(10)
,storeid VARCHAR(10)
,MSRTime VARCHAR(10))
INSERT INTO #T1 VALUES ('x','y','z')
SELECT * FROM #T1
GO
CREATE TABLE #T2
(itemid VARCHAR(10)
,storeid VARCHAR(10)
,MSRTime VARCHAR(10))
INSERT INTO #T2 VALUES ('x','y','z'),('a','b','c')
SELECT * FROM #T2
GO
CREATE TABLE #T3
(itemid VARCHAR(10)
,storeid VARCHAR(10)
,MSRTime VARCHAR(10)
,status VARCHAR(10))
INSERT INTO #T3 VALUES ('x','y','z','D'),('a','b','c','D')
SELECT * FROM #T3
GO
DELETE M
FROM #T2 AS M INNER JOIN
(SELECT itemid,storeid,MSRTime FROM
(SELECT itemid,storeid,MSRTime FROM #T3 WHERE status='D') T1
INTERSECT
(SELECT itemid,storeid,MSRTime FROM
(SELECT * FROM #T2
EXCEPT
SELECT * FROM #T1) T2)) X
ON X.itemid = M.itemid AND X.storeid = M.storeid AND X.MSRTime = M.MSRTime
GO
Not sure if this matches your environment, but programmatically it may be beneficial to limit the results you are comparing with the joins to only those that have a value of D in status. I would also try making a compound key using Coalese so that you are not having to match on three separate joins.
For example -
itemid |storeid|MSRTime|Key
x y z xyz
a b c abc
I am trying to resolve t-sql exercise
I need to update first table with values from second by joining by id. If I can not join then use value from default ID (default iD is the Id that is null)
please run it to see it
declare #t as table (
[id] INT
,val int
)
insert into #t values (null, null)
insert into #t values (2, null)
insert into #t values (3, null)
insert into #t values (4, null)
declare #t2 as table (
[id] INT
,val int
)
insert into #t2 values (null, 11)
insert into #t2 values (2, 22)
insert into #t2 values (3, 33)
select * from #t
select * from #t2
update t
set t.val = t2.val
from #t as t join #t2 as t2
on t.id = t2.id
or
(
(t.id is null or t.id not in (select id from #t2))
and t2.id is null
)
select * from #t
here is result
--#t
id val
---------------
NULL NULL
2 NULL
3 NULL
4 NULL
--#t2
id val
---------------
NULL 11
2 22
3 33
--#t after update
id val
---------------
NULL 11
2 22
3 33
4 NULL
how to make val in last row equal 11?
4 11
This solution left joins to t2 twice and then does a coalesce.
The ON on the second join matches on records that failed on the join and then looks for the "Default" case.
UPDATE t
set t.val = COALESCE(t2.val,t3.val)
from #t as t
LEFT join #t2 as t2
on t.id = t2.id
LEFT JOIN #t2 t3
ON t2.id is null and t3.id is null
See it working here
try this for the update...
update t
set t.val = t2.val
from #t as t join #t2 as t2
on t.id = t2.id
or
(
(t.id is null or not exists (select * from #t2 where id = t.id))
and t2.id is null
)
Problem is with not in operator and null values. This would also work...
update t
set t.val = t2.val
from #t as t join #t2 as t2
on t.id = t2.id
or
(
(t.id is null or t.id not in (select id from #t2 where id is not null))
and t2.id is null
)
Here's a technique that may help.
Start with the kind of simple code you want to be writing:
MERGE INTO #t AS target
USING source
ON target.id = source.id
WHEN MATCHED THEN
UPDATE
SET val = source.val;
Then write a table expression (source) that satisfies the requirements.
Requirement 1: "joining by id"
-- simple existential quantification e.g.
SELECT id, val
FROM #t2 AS T2
WHERE id IN ( SELECT id FROM #t )
Requirement 2: "If I can not join then use value from default ID (default iD is the Id that is null)"
-- first find the id values in the target that do not exist in the source:
SELECT id
FROM #t
EXCEPT
SELECT id
FROM #t2
then cross join the result with the row from the source where Id is null:
SELECT DT1.id, T2.val
FROM ( SELECT id
FROM #t
EXCEPT
SELECT id
FROM #t2 ) AS DT1,
#t2 AS T2
WHERE T2.id IS NULL
At this point you will want to query some test data to ensure each query satisfies its respective requirement.
Union the above two results to form a single table expression:
SELECT id, val
FROM #t2 AS T2
WHERE id IN ( SELECT id
FROM #t )
UNION
SELECT DT1.id, T2.val
FROM ( SELECT id
FROM #t
EXCEPT
SELECT id
FROM #t2 ) AS DT1,
#t2 AS T2
WHERE T2.id IS NULL
Then plug the table expression into the MERGE boilerplate code:
WITH source
AS
(
SELECT id, val
FROM #t2 AS T2
WHERE id IN ( SELECT id
FROM #t )
UNION
SELECT DT1.id, T2.val
FROM ( SELECT id
FROM #t
EXCEPT
SELECT id
FROM #t2 ) AS DT1,
#t2 AS T2
WHERE T2.id IS NULL
)
MERGE INTO #t AS target
USING source
ON target.id = source.id
WHEN MATCHED THEN
UPDATE
SET val = source.val;
Let's say I have three tables:
table1 fields:
memberid | name
table2 fields:
interestId | interestName
table3 (used to make a relation between member and interest) fields:
memberid | interestId
and now I know I can user inner join to select one member's all interests.
But how can I cascade all the interests in a single row???
For example, I can select this result:
memberid name interstId interestName
1 dennis 1 play basketball
1 dennis 2 music
1 dennis 3 moive
but the result i want to get is:
memberid name interests
1 dennis play basketball, music, moive
How can I write the SQL query?
Thanks in advance!
In SQL Server 2005 onwards, You can use XML Path() to concatenate values. It appears to be very performant too.
EDIT : Have tested the following and works
SELECT
t1.memberid,
t1.[name],
ISNULL(STUFF(
(
SELECT
', ' + t2.interestName
FROM
table2 t2
INNER JOIN
table3 t3
ON
t2.interestId = t3.interestId
WHERE
t3.memberid = t1.memberid
FOR XML PATH('')
), 1, 2, ''
), 'None') As interests
FROM
table1 t1
GROUP BY
t1.memberid,
t1.[name]
Example code:
DECLARE #table1 TABLE ( memberid INT IDENTITY(1,1), name VARCHAR(25) )
INSERT INTO #table1 VALUES('dennis');
INSERT INTO #table1 VALUES('mary');
INSERT INTO #table1 VALUES('bill');
DECLARE #table2 TABLE ( interestId INT IDENTITY(1,1), interestName VARCHAR(25) )
INSERT INTO #table2 VALUES('play basketball');
INSERT INTO #table2 VALUES('music');
INSERT INTO #table2 VALUES('movie');
INSERT INTO #table2 VALUES('play hockey');
INSERT INTO #table2 VALUES('wine tasting');
INSERT INTO #table2 VALUES('cheese rolling');
DECLARE #table3 TABLE ( memberid INT, interestId INT )
INSERT INTO #table3 VALUES(1,1);
INSERT INTO #table3 VALUES(1,2);
INSERT INTO #table3 VALUES(1,3);
INSERT INTO #table3 VALUES(2,2);
INSERT INTO #table3 VALUES(2,4);
INSERT INTO #table3 VALUES(2,6);
INSERT INTO #table3 VALUES(3,1);
INSERT INTO #table3 VALUES(3,5);
INSERT INTO #table3 VALUES(3,6);
SELECT
t1.memberid,
t1.[name],
ISNULL(STUFF(
(
SELECT
', ' + t2.interestName
FROM
#table2 t2
INNER JOIN
#table3 t3
ON
t2.interestId = t3.interestId
WHERE
t3.memberid = t1.memberid
FOR XML PATH('')
), 1, 2, ''
), 'None') As interests
FROM
#table1 t1
GROUP BY
t1.memberid,
t1.[name]
Results
memberid name interests
----------- -----------------------------------------------------------------------
1 dennis play basketball, music, movie
2 mary music, play hockey, cheese rolling
3 bill play basketball, wine tasting, cheese rolling
It depends on the DB you are using. Take a look at this question: Show a one to many relationship as 2 columns - 1 unique row (ID & comma separated list)
since you didn't specify your database, I can advice to take a look at left (right) joins.
http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
GROUP_CONCAT
just saw the comment on the dbms system, but it would work with mysql.
SELECT t1.memberid, t1.name,
STUFF(
( SELECT ', ' + interestName
FROM table2 t2
inner join table3 as t3
on t2.interestId = t3.interestId and t3.memberid = t1.memberid
FOR XML PATH('') //use to merge the interests
), 1, 2, ''
) As interests
FROM table1
This works
Depends on particular database. Maybe it will help you (using T-SQL and MS SQL Server) for a known memberid:
declare #result varchar(8000)
set #result = ''
declare #memberid int
set #memberid = 1
select #result = str(#memberid) + ' ' + (select name from table1 where memberid = #memberid) + ' '
select #result = #result + str(interestid) + ' ' + interest
from
(
select table2.interestid, table2.interestname
from table3
inner join table2 on table2.interestid = table3.interestid
where table3.memberid = #memberid
) t1
select left(#result, LEN(#result) - 1)