I have a stored procedure that I cannot modify, but I need to add a where clause to filter it even more. What would be the best way to do this without inserting data from stored procedure to a temptable then doing a where on that temptable. Is there another way?
The store procedure is executable but filtering happens inside the select statement so you should bring the result in a table to select it.
There is no way except temp tables.
Table valued Udf also has table like temp tables.
Related
I am using Redshift. I want a query to delete selected rows from a redshift table if the table exists otherwise just ignore the statement.
Redshift's SQL dialect doesn't contain control-of-flow statements like IF.. THEN so you are not going to be able to do this in a single SQL statement.
Your application or process will need to first query the Redshift table metadata to determine if a table exists e.g.
select 1 from pg_tables where schemaname = 'myschema' and tablename = 'myschema';
If data is returned (i.e. the table exists) then the application or process will execute the delete statement, if no data is returned the application or process does nothing. Basically you need to handle the "if this then do this" logic externally to Redshift.
I recommend #Nathan's answer. I would use python/psycopg2 to set up this logic. The first query would check for the table's existence in pg_tables (eg SELECT count(1) FROM pg_tables WHERE tablename='foo'), and store the result in a variable. Then you'd check the results of that variable to decide whether to kick off a second query (your delete).
But, maybe you don't want to do it in Python. You're just all about Redshift (it's pretty sweet). You could just run the DELETE query in Redshift. If the table is not present, the query fails and nothing happens. If the table is, you delete your data. There's no harm in generating an error here.
I know that in plpgsql if one would want to refer to the new inserted row, you can use "NEW".
How can I do this in T-SQL (transact sql)?
The following is the trigger I am trying to create:
CREATE Trigger setAlertId on rules_table
FOR INSERT AS
DECLARE #max_id integer
SELECT #max_id = (select max(AlertId) from rules_table)
NEW.AlertId = #max_id+1
END
GO
I get the error message:
Incorrect syntax near 'NEW'
Thanks.
inserted and deleted pseudo tables:
DML trigger statements use two special tables: the deleted table and the inserted tables. SQL Server automatically creates and manages these tables. You can use these temporary, memory-resident tables to test the effects of certain data modifications and to set conditions for DML trigger actions. You cannot directly modify the data in the tables
In your case why dont you use an identity on the alertid field that increments itself?
If you want to do it in your trigger you will need to select your primary key from inserted and then do an update on rules tables.
I have been trying to figure this out the ENTIRE DAY :( ...
I have several stored procedures (in the same database as well as different databases) that do the same thing.
Creates temp table with name X.
Does processing with X.
Drops X.
The problem is that these stored procedures are creating temp tables with the same name. How do I know which temp table to drop once I'm done with the processing if they all have the name and I can't really DROP using "LIKE" because a temp table might be being used by a different stored procedure?
Here's a scenario.
SP1 starts -
Create temp table.
...and before it goes on, this happens:
SP2 is about finish
Drop temp table.
If the above happens, SP1 runs into issues. Such as "temp table does not exist"
How do I bypass this issue?
When I go to drop a temp table, I need to make sure I'm dropping the table related to the stored procedure that created it. Is this even possible?
You are trying to solve a problem you don't have. Just drop the table. If you look in SSMS you will really have unique tables. The SP knows which one to drop.
If SP1 and SP2 were using the same table you would have more problems than just drop.
IF OBJECT_ID(N'tempdb..#Temp', N'U') IS NOT NULL DROP TABLE #Temp
CREATE TABLE #Temp (sID INT PRIMARY KEY CLUSTERED);
-- look in SSMS and you will see #temp appended
-- use #temp
IF OBJECT_ID(N'tempdb..#Temp', N'U') IS NOT NULL DROP TABLE #Temp
In SP not sure you even need to drop. I think it will be dropped automatically.
But if you run the first two lines and look in SSMS you will see that you have your own #TEMP - not a shared #TEMP. Run the last line and you will see it go away.
I'm working on an application that imports data from Access to SQL Server 2008. Currently, I'm using a stored procedure to import the data individually by record. I can't go with a bulk insert or anything like that because the data is inserted into two related tables...I have a bunch of fields that go into the Account table (first name, last name, etc.) and three fields that will each have a record in an Insurance table, linked back to the Account table by the auto-incrementing AccountID that's selected with SCOPE_IDENTITY in the stored procedure.
Performance isn't very good due to the number of round trips to the database from the application. For this and some other reasons I'm planning to instead use a staging table and import the data from there. Reading up on my options for approaching this, a cursor that executes the same insert stored procedure on the data in the staging table would make sense. However it appears that cursors are evil incarnate and should be avoided.
Is there any way to insert data into one table, retrieve the auto-generated IDs, then insert data for the same records into another table using the corresponding ID, in a set-based operation? Or is a cursor my only option here?
Look at the OUTPUT clause. You should be able to add it to your INSERT statement to do what you want.
BTW, if you need to output columns into the second table that weren't inserted into the first one, then use MERGE instead of INSERT (as suggested in the comment to the original question) as its OUTPUT clause supports referencing other columns from the source table(s). Otherwise, keeping it with an INSERT is more straightforward, and it does give you access to the inserted identity column.
I'm having experiment to worked out in inserting multiple record into related table using databinding. So, try this!
Hopefully this is very helpful. Follow this link How to insert record into related tables. for more information.
I am wondering what the best / most efficient / common way is to add a row to an SQL Server table using C# and ADO.NET. I know of course that I can just create an SQL statement for that, but first, the destination table schema might vary, so I want to keep this flexible, and second, there are so much columns that I do not want to code and maintain this manually. So I currently use a SqlCommandBuilder that is automatically creating the proper insert statement for me, together with an SQLDataAdapter, like this:
var dataAdapter = new SqlDataAdapter("select * from sometable", _databaseConnection);
new SqlCommandBuilder(dataAdapter);
dataAdapter.Fill(dataTable);
// ... add row to dataTable, fill fields from some external file that
// ... includes column names as well,
//.... add some more field values not from the file, etc. ...
dataAdapter.Update(dataTable);
This seems pretty inefficient though to first grab all the records from the table even though I do not need them for anything (especially considering that there might even already be a million records in there). Using some select statement like select * from sometable where 1=2 would work, but it does not seem like a very clean approach. I imagine there is some different solution for this that I am just not aware of.
Thanks,
Timo
I think the best way to insert rows is by using Stored Procedures through the ADO.NET command object.
If you are inserting massive amounts of data and are using SQL Server 2008 you can pass DataTable objects to a stored procedure by using a User-Defined Table Types.
In SQL:
CREATE TYPE SAMPLE_TABLE_TYPE --
AS
field1 VARCHAR(255)
field2 VARCHAR(255)
CREATE STORED PROCEDURE insert_data
AS
#data Sample_TABLE_TYPE
BEGIN
INSERT INTO table1 (field1, field1)
SELECT username, password FROM #data;
In .NET:
DataTable myTable = new DataTable();
myTable.Columns.Add(new DataColumn("field1", typeof(string));
myTable.Columns.Add(new DataColumn("field1", typeof(string));
SqlCommand command = new SqlCommand(conn, CommandType.StoredProcedure);
command.Parameters.Add("#data", myTable);
command.ExecuteNonQuery();
If you data also contains updates you can use the new MERGE function used in SQL Server 2008 to efficiently perform both inserts and updates in the same procedure.
However, if creating User-Defined Table Types and creating stored procedures is too much work, and you need a complete dynamic solution I would stick with what you have, with the recommendation of using the
Where 1 = 0
appended to your SQL text.
You also can use "SELECT TOP(0) * FROM SOMETABLE;" query.