I keep coming across this DELETE FROM FROM syntax in SQL Server, and having to remind myself what it does.
DELETE FROM tbl
FROM #tbl
INNER JOIN tbl ON fk = pk AND DATEDIFF(day, #tbl.date, tbl.Date) = 0
EDIT: To make most of the comments and suggested answers make sense, the original question had this query:
DELETE FROM tbl
FROM tbl2
As far as I understand, you would use a structure like this where you are restricting which rows to delete from the first table based on the results of the from query. But to do that you need to have a correlation between the two.
In your example there is no correlation, which will effectively be a type of cross join which means "for every row in tbl2, delete every row in tbl1". In other words it will delete every row in the first table.
Here is an example:
declare #t1 table(A int, B int)
insert #t1 values (15, 9)
,(30, 10)
,(60, 11)
,(70, 12)
,(80, 13)
,(90, 15)
declare #t2 table(A int, B int)
insert #t2 values (15, 9)
,(30, 10)
,(60, 11)
delete from #t1 from #t2
The result is an empty #t1.
On the other hand this would delete just the matching rows:
delete from #t1 from #t2 t2 join #t1 t1 on t1.A=t2.A
I haven't seen this anywhere before. The documentation of DELETE tells us:
FROM table_source Specifies an additional FROM clause. This
Transact-SQL extension to DELETE allows specifying data from
and deleting the corresponding rows from the table in
the first FROM clause.
This extension, specifying a join, can be used instead of a subquery
in the WHERE clause to identify rows to be removed.
Later in the same document we find
D. Using joins and subqueries to data in one table to delete rows in
another table The following examples show two ways to delete rows in
one table based on data in another table. In both examples, rows from
the SalesPersonQuotaHistory table in the AdventureWorks2012 database
are deleted based on the year-to-date sales stored in the SalesPerson
table. The first DELETE statement shows the ISO-compatible subquery
solution, and the second DELETE statement shows the Transact-SQL FROM
extension to join the two tables.
With these examples to demonstrate the difference
-- SQL-2003 Standard subquery
DELETE FROM Sales.SalesPersonQuotaHistory
WHERE BusinessEntityID IN
(SELECT BusinessEntityID
FROM Sales.SalesPerson
WHERE SalesYTD > 2500000.00);
-- Transact-SQL extension
DELETE FROM Sales.SalesPersonQuotaHistory
FROM Sales.SalesPersonQuotaHistory AS spqh
INNER JOIN Sales.SalesPerson AS sp
ON spqh.BusinessEntityID = sp.BusinessEntityID
WHERE sp.SalesYTD > 2500000.00;
The second FROM mentions the same table in this case. This is a weird way to get something similar to an updatable cte or a derived table
In the third sample in section D the documentation states clearly
-- No need to mention target table more than once.
DELETE spqh
FROM
Sales.SalesPersonQuotaHistory AS spqh
INNER JOIN Sales.SalesPerson AS sp
ON spqh.BusinessEntityID = sp.BusinessEntityID
WHERE sp.SalesYTD > 2500000.00;
So I get the impression, the sole reason for this was to use the real table's name as the DELETE's target instead of an alias.
Related
I have been trying to do something in SQL and I cannot quite find the right answer on Stack Overflow. I have a table (called RMBS_STANDARDIZED) already created and it has a column LOAN_PERC_ISSUER. The table is the union of several other tables where I standardized naming convention.
What I want to do after loading the table is to update it with this inner query (noting when I run this it returns the correct values are returned but obviously as a single column). Therefore, I want to store the returned query in the table.
SELECT
ISSUER_SERIES,
SUM(COALESCE(LOAN_BALANCE, 0)) AS TOTAL_BALANCE
FROM
RMBS_STANDARDIZED
GROUP BY
ISSUER_SERIES
The insert query I am trying to use is
INSERT INTO RMBS_STANDARDIZED (LOAN_PERC_ISSUER)
SELECT
COALESCE(T1.LOAN_BALANCE, 0) / T2.TOTAL_BALANCE
FROM
RMBS_STANDARDIZED T1
LEFT JOIN
(SELECT
ISSUER_SERIES,
SUM(COALESCE(LOAN_BALANCE, 0)) AS TOTAL_BALANCE
FROM
RMBS_STANDARDIZED
GROUP BY
ISSUER_SERIES) T2 ON T1.ISSUER_SERIES = T2.ISSUER_SERIES
But I get the following error
Cannot insert the value NULL into column 'ISSUER'
If I adjust the ISSUER column to allow NULLs, then the column does not update or remains NULL.
Alternatively, I have tried the following
ALTER TABLE RMBS_STANDARDIZED
ADD New_Column AS (SELECT
COALESCE(T1.LOAN_BALANCE, 0) / T2.TOTAL_BALANCE
FROM
RMBS_STANDARDIZED T1
LEFT JOIN
(SELECT
ISSUER_SERIES,
SUM(COALESCE(LOAN_BALANCE, 0)) AS TOTAL_BALANCE
FROM
RMBS_STANDARDIZED GROUP BY ISSUER_SERIES) T2
ON T1.ISSUER_SERIES = T2.ISSUER_SERIES)
But get the following error
Subqueries are not allowed in this context. Only scalar expressions are allowed.
Any ideas would be helpful. I am better off using a CTE or creating a temp/hash table before creating the final table? I am using SQL Server and SQL Server Management Studio.
Your first query fail because LOAN_PERC_ISSUER has a NOT NULL constraint. Rewrite your query as :
SELECT COALESCE(T1.LOAN_BALANCE / T2.TOTAL_BALANCE, 0)
FROM RMBS_STANDARDIZED AS T1
LEFT OUTER JOIN (SELECT ISSUER_SERIES,
SUM(COALESCE(LOAN_BALANCE, 0)) AS TOTAL_BALANCE
FROM RMBS_STANDARDIZED
GROUP BY ISSUER_SERIES) AS T2
ON T1.ISSUER_SERIES = T2.ISSUER_SERIES;
A computed column cannot have subquery of anykind and must use only data comming from the row's values. There is a possibility to put the query into an UDF and use the UDF for the computed column, but it is not well recommended...
A much proper way is to use a trigger
I have an insert Query and inserting data using SELECT query and certain joins between tables.
While running that query, it is giving error "String or binary data would be truncated".
There are thousands of rows and multiple columns I am trying to insert in that table.
So it is not possible to visualize all data and see what data is throwing this error.
Is there any specific way to identify which column is throwing this error? or any specific record not getting inserted properly and resulted into this error?
I found one article on this:
RareSQL
But this is when we insert data using some values and that insert is one by one.
I am inserting multiple rows at the same time using SELECT statements.
E.g.,
INSERT INTO TABLE1 VALUES (COLUMN1, COLUMN2,..) SELECT COLUMN1, COLUMN2,.., FROM TABLE2 JOIN TABLE3
Also, in my case, I am having multiple inserts and update statements and even not sure which statement is throwing this error.
You can do a selection like this:
select TABLE2.ID, TABLE3.ID TABLE1.COLUMN1, TABLE1.COLUMN2, ...
FROM TABLE2
JOIN TABLE3
ON TABLE2.JOINCOLUMN1 = TABLE3.JOINCOLUMN2
LEFT JOIN TABLE1
ON TABLE1.COLUMN1 = TABLE2.COLUMN1 and TABLE1.COLUMN2 = TABLE2.COLUMN2, ...
WHERE TABLE1.ID = NULL
The first join reproduces the selection you have been using for the insert and the second join is a left join, which will yield null values for TABLE1 if a row having the exact column values you wanted to insert does not exist. You can apply this logic to your other queries, which were not given in the question.
You might just have to do it the hard way. To make it a little simpler, you can do this
Temporarily remove the insert command from the query, so you are getting a result set out of it. You might need to give some of the columns aliases if they don't come with one. Then wrap that select query as a subquery, and test likely columns (nvarchars, etc) like this
Select top 5 len(Col1), *
from (Select col1, col2, ... your query (without insert) here) A
Order by 1 desc
This will sort the rows with the largest values in the specified column first and just return the rows with the top 5 values - enough to see if you've got a big problem or just one or two rows with an issue. You can quickly change which column you're checking simply by changing the column name in the len(Col1) part of the first line.
If the subquery takes a long time to run, create a temp table with the same columns but with the string sizes large (like varchar(max) or something) so there are no errors, and then you can do the insert just once to that table, and run your tests on that table instead of running the subquery a lot
From this answer,
you can use temp table and compare with target table.
for example this
Insert into dbo.MyTable (columns)
Select columns
from MyDataSource ;
Become this
Select columns
into #T
from MyDataSource;
select *
from tempdb.sys.columns as TempCols
full outer join MyDb.sys.columns as RealCols
on TempCols.name = RealCols.name
and TempCols.object_id = Object_ID(N'tempdb..#T')
and RealCols.object_id = Object_ID(N'MyDb.dbo.MyTable)
where TempCols.name is null -- no match for real target name
or RealCols.name is null -- no match for temp target name
or RealCols.system_type_id != TempCols.system_type_id
or RealCols.max_length < TempCols.max_length ;
I'm trying to update a column in one table (#TEMPTABLE) using data in another table (#PEOPLE) by using the REPLACE() function.
#TEMPTABLE has a column called "NameString' that is a long string with a user's name and ID.
#PEOPLE has a column for ID, and IDnumber.
UPDATE #TEMPTABLE
SET NAMEString = REPLACE(NAMEString, a.[ID], a.[IDNumber]) FROM #PEOPLE a
I'm trying to replace all the ID's in the NameString Column with the IDnumbers coming from #People table.
You need to give it a join criterion. For example:
update #TEMPTABLE
set NAMEString = replace(a.NAMEString, a.ID, b.IDNumber)
from #TEMPTABLE a
left join #PEOPLE b
on a.id = b.ID
Also, make sure to reference the right table when you use the IDNumber column - your original query doesn't actually use the table containing IDNumber at all, as far as I can tell from your description of your tables.
Note that my example assumes there's an ID field in #TempTable, or something else to join on - otherwise, you may need to extract it from the NameString column first.
I want to join 2 tables using an Inner Join on 2 columns, both are of (nvarchar, null) type. The 2 columns have the same data in them, but the join condition is failing. I think it is due to the spaces contained in the column values.
I have tried LTRIM, RTRIM also
My query:
select
T1.Name1, T2.Name2
from
Table1 T1
Inner Join
Table2 on T1.Name1 = T2.Name2
I have also tried like this:
on LTRIM(RTRIM(T1.Name1)) = LTRIM(RTRIM(T2.Name2))
My data:
Table1 Table2
------ ------
Name1(Column) Name2(Column)
----- ------
Employee Data Employee Data
Customer Data Customer Data
When I check My data in 2 tables with
select T1.Name1,len(T1.Name1)as Length1,Datalength(T1.Name1)as DataLenght1 from Table1 T1
select T2.Name2,len(T2.Name2)as Length2,Datalength(T2.Name2)as DataLenght2 from Table2 T2
The result is different Length and DataLength Values for the 2 tables,They are not same for 2 tables.
I can't change the original data in the 2 tables. How can I fix this issue.
Thank You
Joins do not have special rules for equality. The equality operator always works the same way. So if a = b then the join on a = b would work. Therefore, a <> b.
Check the contents of those fields. They will not be the same although you think they are:
select convert(varbinary(max), myCol) from T
Unicode has invisible characters (that only ever seem to cause trouble).
declare #t table (name varchar(20))
insert into #t(name)values ('Employee Data'),('Customer Data')
declare #tt table (name varchar(20))
insert into #tt(name)values ('EmployeeData'),('CustomerData')
select t.name,tt.name from #t t
INNER JOIN #tt tt
ON RTRIM(LTRIM(REPLACE(t.name,' ',''))) = RTRIM(LTRIM(REPLACE(tt.name,' ','')))
I would follow the following schema
Create a new table to store all the possible names
Add needed keys and indexes
Populate with existing names
Add columns to your existing tables to store the index of the name
Create relative foreign keys
Populate the new columns with correct indexes
Create procedure to perform an insert in new tables names only in case the value is not existing
Perform the join using the new indexes
I'm trying to build a mapping table to associate the IDs of new rows in a table with those that they're copied from. The OUTPUT INTO clause seems perfect for that, but it doesn't seem to behave according to the documentation.
My code:
DECLARE #Missing TABLE (SrcContentID INT PRIMARY KEY )
INSERT INTO #Missing
( SrcContentID )
SELECT cshadow.ContentID
FROM Private.Content AS cshadow
LEFT JOIN Private.Content AS cglobal ON cshadow.Tag = cglobal.Tag
WHERE cglobal.ContentID IS NULL
PRINT 'Adding new content headers'
DECLARE #Inserted TABLE (SrcContentID INT PRIMARY KEY, TgtContentID INT )
INSERT INTO Private.Content
( Tag, Description, ContentDate, DateActivate, DateDeactivate, SortOrder, CreatedOn, IsDeleted, ContentClassCode, ContentGroupID, OrgUnitID )
OUTPUT cglobal.ContentID, INSERTED.ContentID INTO #Inserted (SrcContentID, TgtContentID)
SELECT Tag, Description, ContentDate, DateActivate, DateDeactivate, SortOrder, CreatedOn, IsDeleted, ContentClassCode, ContentGroupID, NULL
FROM Private.Content AS cglobal
INNER JOIN #Missing AS m ON cglobal.ContentID = m.SrcContentID
Results in the error message:
Msg 207, Level 16, State 1, Line 34
Invalid column name 'SrcContentID'.
(line 34 being the one with the OUTPUT INTO)
Experimentation suggests that only rows that are actually present in the target of the INSERT can be selected in the OUTPUT INTO. But this contradicts the docs in the books online. The article on OUTPUT Clause has example E that describes a similar usage:
The OUTPUT INTO clause returns values
from the table being updated
(WorkOrder) and also from the Product
table. The Product table is used in
the FROM clause to specify the rows to
update.
Has anyone worked with this feature?
(In the meantime I've rewritten my code to do the job using a cursor loop, but that's ugly and I'm still curious)
You can do this with a MERGE in Sql Server 2008. Example code below:
--drop table A
create table A (a int primary key identity(1, 1))
insert into A default values
insert into A default values
delete from A where a>=3
-- insert two values into A and get the new primary keys
MERGE a USING (SELECT a FROM A) AS B(a)
ON (1 = 0) -- ignore the values, NOT MATCHED will always be true
WHEN NOT MATCHED THEN INSERT DEFAULT VALUES -- always insert here for this example
OUTPUT $action, inserted.*, deleted.*, B.a; -- show the new primary key and source data
Result is
INSERT, 3, NULL, 1
INSERT, 4, NULL, 2
i.e. for each row the new primary key (3, 4) and the old one (1, 2). Creating a table called e.g. #OUTPUT and adding " INTO #OUTPUT;" at the end of the OUTPUT clause would save the records.
I've verified that the problem is that you can only use INSERTED columns. The documentation seems to indicate that you can use from_table_name, but I can't seem to get it to work (The multi-part identifier "m.ContentID" could not be bound.):
TRUNCATE TABLE main
SELECT *
FROM incoming
SELECT *
FROM main
DECLARE #Missing TABLE (ContentID INT PRIMARY KEY)
INSERT INTO #Missing(ContentID)
SELECT incoming.ContentID
FROM incoming
LEFT JOIN main
ON main.ContentID = incoming.ContentID
WHERE main.ContentID IS NULL
SELECT *
FROM #Missing
DECLARE #Inserted TABLE (ContentID INT PRIMARY KEY, [Content] varchar(50))
INSERT INTO main(ContentID, [Content])
OUTPUT INSERTED.ContentID /* incoming doesn't work, m doesn't work */, INSERTED.[Content] INTO #Inserted (ContentID, [Content])
SELECT incoming.ContentID, incoming.[Content]
FROM incoming
INNER JOIN #Missing AS m
ON m.ContentID = incoming.ContentID
SELECT *
FROM #Inserted
SELECT *
FROM incoming
SELECT *
FROM main
Apparently the from_table_name prefix is only allowed on DELETE or UPDATE (or MERGE in 2008) - I'm not sure why:
from_table_name
Is a column prefix that specifies a table included in the FROM clause of a DELETE or UPDATE statement that is used to specify the rows to update or delete.
If the table being modified is also specified in the FROM clause, any reference to columns in that table must be qualified with the INSERTED or DELETED prefix.
I'm running into EXACTLY the same problem as you are, I feel your pain...
As far as I've been able to find out there's no way to use the from_table_name prefix with an INSERT statement.
I'm sure there's a viable technical reason for this, and I'd love to know exactly what it is.
Ok, found it, here's a forum post on why it doesn't work:
MSDN forums
I think I found a solution to this problem, it sadly involves a temporary table, but at least it'll prevent the creation of a dreaded cursor :)
What you need to do is add an extra column to the table you're duplicating records from and give it a 'uniqueidentifer' type.
then declare a temporary table:
DECLARE #tmptable TABLE (uniqueid uniqueidentifier, original_id int, new_id int)
insert the the data into your temp table like this:
insert into #tmptable
(uniqueid,original_id,new_id)
select NewId(),id,0 from OriginalTable
the go ahead and do the real insert into the original table:
insert into OriginalTable
(uniqueid)
select uniqueid from #tmptable
Now to add the newly created identity values to your temp table:
update #tmptable
set new_id = o.id
from OriginalTable o inner join #tmptable tmp on tmp.uniqueid = o.uniqueid
Now you have a lookup table that holds the new id and original id in one record, for your using pleasure :)
I hope this helps somebody...
(MS) If the table being modified is also specified in the FROM clause, any reference to columns in that table must be qualified with the INSERTED or DELETED prefix.
In your example, you can't use cglobal table in the OUTPUT unless it's INSERTED.column_name or DELETED.column_name:
INSERT INTO Private.Content
(Tag)
OUTPUT cglobal.ContentID, INSERTED.ContentID
INTO #Inserted (SrcContentID, TgtContentID)
SELECT Tag
FROM Private.Content AS cglobal
INNER JOIN #Missing AS m ON cglobal.ContentID = m.SrcContentID
What worked for me was a simple alias table, like this:
INSERT INTO con1
(Tag)
OUTPUT **con2**.ContentID, INSERTED.ContentID
INTO #Inserted (SrcContentID, TgtContentID)
SELECT Tag
FROM Private.Content con1
**INNER JOIN Private.Content con2 ON con1.id=con2.id**
INNER JOIN #Missing AS m ON con1.ContentID = m.SrcContentID