I have a table table1 with fields id(int), name(nchar), grade(real).
The following code isn't working. There are no errors or warnings. The code executes well but the number of affected rows = 0.
MsSql Server
sqlConnection1.Open();
SqlCommand cmd = new SqlCommand("Delete from [table1] where [id] = 1", sqlConnection1);
int c = cmd.ExecuteNonQuery();
sqlConnection1.Close();
All other queries are working well.
A slight expansion of what others have already asked. Are you certain that there are records to be deleted in your target table? Moreover, are you certain you are getting the table from the right database? It's possible the default is tempdb, for instance, and that just happens to have a table with the target name and with an id column.
First do a select from the SQL prompt to insure there are items of the type you are looking for:
SELECT TOP 10 * FROM [database].[schema].[table1] WHERE [id] = 1
If that provides results, try changing your command to explicitly state the database and schema as well:
DELETE FROM [database].[schema].[table1] WHERE [id] = 1
Thoughts:
is there a row with [id] 1
do you have a trigger that is firing?
my guess would be the second... the number is after triggers have been taken into account, and is the number of rows from the last operation.
I know this might sound silly, but is there data in the call with an ID of 1? Can you see it executing via SQL Profiler? What happens if you execute it via SSMS?
Does the query work when you run it in Sql Management studio?
Apart from Marc Gravell's comment about triggers you should also check, if there are foreign key constraints with ON DELETE RESTRICT` in place (and the error message somehow disappears before getting to you ...)
Related
I have found a strange phenomena on MSSQL server.
Let say we have a table:
CREATE TABLE [testTable]
(
[ID] [numeric](11, 0) NOT NULL,
[Updated] [datetime] NULL,
PRIMARY KEY (ID)
);
I do a simple select based on Updated field:
SELECT TOP 10000 ID, Updated
FROM testTable
WHERE Updated>='2013-05-22 08:55:12.152'
ORDER BY Updated
And now comes the fun part: how can I have in result set double records - I mean same ID in 2 records with different Updated value.
For me it seems to be, that the Updated datetime value was changed and it was included one more time in result set. But is it possible?
UPDATE:
Source code I using for downloading data from SQL server:
using (SqlCommand cmd = new SqlCommand(sql, Connection) { CommandTimeout = commandTimeout })
{
using (System.Data.SqlClient.SqlDataAdapter adapter = new System.Data.SqlClient.SqlDataAdapter(cmd))
{
DataTable retVal = new DataTable();
adapter.Fill(retVal);
return retVal;
}
}
Connection = SqlConnection
sql = "SELECT TOP 10000 ...."
Your question seems to lack some details but here's my ideas.
The first case I'd think of would be that you are somehow selecting those IDs twice (could be a join, group by, ...). Please manually check inside your table (in MSSQL Server rather than inside a function or method) to see if there is dupplicated IDs. If there is, the issue is that your Primary Key hasn't been set correctly. Otherwise, you will need to provide all the relevant code that is used to select the data in order to get more help.
Another case might be that someone or something altered the primary key so it is on both ID and Updated, allowing the same ID to be inserted twice as long as the Updated field doesn't match too.
You may also try this query to see if it gets dupplicated IDs inside your context:
SELECT ID
from testTable
ORDER BY ID
I hope this helps.
I'm trying to insert records using a high performance table parameter method ( http://www.altdevblogaday.com/2012/05/16/sql-server-high-performance-inserts/ ), and I'm curious if it's possible to retrieve back the identity values for each record I insert.
At the moment, the answer appears to be no - I insert the data, then retrieve back the identity values, and they don't match. Specifically, they don't match about 75% of the time, and they don't match in unpredictable ways. Here's some code that replicates this issue:
// Create a datatable with 100k rows
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("item_id", typeof(int)));
dt.Columns.Add(new DataColumn("comment", typeof(string)));
for (int i = 0; i < 100000; i++) {
dt.Rows.Add(new object[] { 0, i.ToString() });
}
// Insert these records and retrieve back the identity
using (SqlConnection conn = new SqlConnection("Data Source=localhost;Initial Catalog=testdb;Integrated Security=True")) {
conn.Open();
using (SqlCommand cmd = new SqlCommand("proc_bulk_insert_test", conn)) {
cmd.CommandType = CommandType.StoredProcedure;
// Adding a "structured" parameter allows you to insert tons of data with low overhead
SqlParameter param = new SqlParameter("#mytable", SqlDbType.Structured);
param.Value = dt;
cmd.Parameters.Add(param);
SqlDataReader dr = cmd.ExecuteReader();
// Set all the records' identity values
int i = 0;
while (dr.Read()) {
dt.Rows[i].ItemArray = new object[] { dr.GetInt32(0), dt.Rows[i].ItemArray[1] };
i++;
}
dr.Close();
}
// Do all the records' ID numbers match what I received back from the database?
using (SqlCommand cmd = new SqlCommand("SELECT * FROM bulk_insert_test WHERE item_id >= #base_identity ORDER BY item_id ASC", conn)) {
cmd.Parameters.AddWithValue("#base_identity", (int)dt.Rows[0].ItemArray[0]);
SqlDataReader dr = cmd.ExecuteReader();
DataTable dtresult = new DataTable();
dtresult.Load(dr);
}
}
The database is defined using this SQL server script:
CREATE TABLE bulk_insert_test (
item_id int IDENTITY (1, 1) NOT NULL PRIMARY KEY,
comment varchar(20)
)
GO
CREATE TYPE bulk_insert_table_type AS TABLE ( item_id int, comment varchar(20) )
GO
CREATE PROCEDURE proc_bulk_insert_test
#mytable bulk_insert_table_type READONLY
AS
DECLARE #TableOfIdentities TABLE (IdentValue INT)
INSERT INTO bulk_insert_test (comment)
OUTPUT Inserted.item_id INTO #TableOfIdentities(IdentValue)
SELECT comment FROM #mytable
SELECT * FROM #TableOfIdentities
Here's the problem: the values returned from proc_bulk_insert_test are not in the same order as the original records were inserted. Therefore, I can't programmatically assign each record the item_id value I received back from the OUTPUT statement.
It seems like the only valid solution is to SELECT back the entire list of records I just inserted, but frankly I'd prefer any solution that would reduce the amount of data piped across my SQL Server's network card. Does anyone have better solutions for large inserts while still retrieving identity values?
EDIT: Let me try clarifying the question a bit more. The problem is that I would like my C# program to learn what identity values SQL Server assigned to the data that I just inserted. The order isn't essential; but I would like to be able to take an arbitrary set of records within C#, insert them using the fast table parameter method, and then assign their auto-generated ID numbers in C# without having to requery the entire table back into memory.
Given that this is an artificial test set, I attempted to condense it into as small of a readable bit of code as possible. Let me describe what methods I have used to resolve this issue:
In my original code, in the application this example came from, I would insert about 15 million rows using 15 million individual insert statements, retrieving back the identity value after each insert. This worked but was slow.
I revised the code using high performance table parameters for insertion. I would then dispose of all of the objects in C#, and read back from the database the entire objects. However, the original records had dozens of columns with lots of varchar and decimal values, so this method was very network traffic intensive, although it was fast and it worked.
I now began research to figure out whether it was possible to use the table parameter insert, while asking SQL Server to just report back the identity values. I tried scope_identity() and OUTPUT but haven't been successful so far on either.
Basically, this problem would be solved if SQL Server would always insert the records in exactly the order I provided them. Is it possible to make SQL server insert records in exactly the order they are provided in a table value parameter insert?
EDIT2: This approach seems very similar to what Cade Roux cites below:
http://www.sqlteam.com/article/using-the-output-clause-to-capture-identity-values-on-multi-row-inserts
However, in the article, the author uses a magic unique value, "ProductNumber", to connect the inserted information from the "output" value to the original table value parameter. I'm trying to figure out how to do this if my table doesn't have a magic unique value.
Your TVP is an unordered set, just like a regular table. It only has order when you specify as such. Not only do you not have any way to indicate actual order here, you're also just doing a SELECT * at the end with no ORDER BY. What order do you expect here? You've told SQL Server, effectively, that you don't care. That said, I implemented your code and had no problems getting the rows back in the right order. I modified the procedure slightly so that you can actually tell which identity value belongs to which comment:
DECLARE #TableOfIdentities TABLE (IdentValue INT, comment varchar(20))
INSERT INTO bulk_insert_test (comment)
OUTPUT Inserted.item_id, Inserted.comment
INTO #TableOfIdentities(IdentValue, comment)
SELECT comment FROM #mytable
SELECT * FROM #TableOfIdentities
Then I called it using this code (we don't need all the C# for this):
DECLARE #t bulk_insert_table_type;
INSERT #t VALUES(5,'foo'),(2,'bar'),(3,'zzz');
SELECT * FROM #t;
EXEC dbo.proc_bulk_insert_test #t;
Results:
1 foo
2 bar
3 zzz
If you want to make sure the output is in the order of identity assignment (which isn't necessarily the same "order" that your unordered TVP has), you can add ORDER BY item_id to the last select in your procedure.
If you want to insert into the destination table so that your identity values are in an order that is important to you, then you have a couple of options:
add a column to your TVP and insert the order into that column, then use a cursor to iterate over the rows in that order, and insert one at a time. Still more efficient than calling the entire procedure for each row, IMHO.
add a column to your TVP that indicates order, and use an ORDER BY on the insert. This isn't guaranteed, but is relatively reliable, particularly if you eliminate parallelism issues using MAXDOP 1.
In any case, you seem to be placing a lot of relevance on ORDER. What does your order actually mean? If you want to place some meaning on order, you shouldn't be doing so using an IDENTITY column.
You specify no ORDER BY on this: SELECT * FROM #TableOfIdentities so there's no guarantee of order. If you want them in the same order they were sent, do an INNER JOIN in that to the data that was inserted with an ORDER BY which matches the order the rows were sent in.
I am fairly new to C# and SQL, so this may be a very easy question to answer.
I am trying to add a row to a table (EventList) through C# code. I have opened my SqlConnection without any issues, and I know I am connected to the correct database as some earlier code is querying for rows in one of the tables and it's returning the correct keys.
The SQL query to insert the row into the table is like this:
sqlCmd.CommandText =
"insert into EventList values ('" +
eventListIdentifier + "','" +
eventId.ToString() + "')";
sqlCmd.ExecuteNonQuery();
I am using SQL Server Management Studio Express to view the tables in my database. After running the above query, I right-click on the EventList table and click Open Table.
I am not seeing the new row added based on the above call. Any ideas what I may be doing wrong?
Update 1
The data types I'm inserting are:
eventListIdentifier (varchar(100), null)
eventId (varchar(8000), null)
I manually created the same query in SSMS like this:
insert into EventList(eventListIdentifier, eventId ) values('test', 'blah')
and says the following:
(1 row(s) affected)
However no row has been added to the table when I right-click on it and open it.
Update 2
Output of System.Console.WriteLine(sqlCmd.CommandText); as requested by #billinkc:
insert into EventList(eventListIdentifier, eventId) values ('7/09/2011 10:43:55 AM','7')
Any errors? What happens if you output the SQL statement instead of executing it and copy/paste it into SSMS?
Try specifying the columns in the insert:
insert into EventList(col1, col2) values (...)
Also, use parameters instead of string concatenation. The reasons for doing so are well documented in about 200000 questions here already. Just search for SQL injection.
Don't use Open Table due to the cache/refresh bug I pointed out in my comment. Just re-run the same query in a query window:
SELECT * FROM dbo.EventList
-- WHERE EventId = <EventId>
;
You haven't really provided enough detail to help. At the least, it would be helpful to know:
Are there any errors?
Is the code snippet you posted in a try/catch block?
What datatypes are the variables you are inserting?
Are you using a Transaction that wasn't committed?
Finally, how is the table sorted? Are there any indexes, including a primary key?
If you run a SELECT in Management Studio based on the value in eventId, do you see the record?
I'm stuck on a little problem concerning database.
Once a month I get a XML file with customer information (Name, address, city,etc.). My primary key is a customer number which is provided in the XML file.
I have no trouble inserting the information in the database;
var cmd = new SqlCommand("insert into [customer_info]
(customer_nr, firstname, lastname, address_1, address_2, address_3.......)");
//some code
cmd.ExecuteNonQuery();
Now, I would like to update my table or just fill it with new information. How can I achieve this?
I've tried using TableAdapter but it does not work.
And I'm only permitted to add one XML because I can only have one customer_nr as primary key.
So basically how do I update or fill my table with new information?
Thanks.
One way would be to bulk insert the data into a new staging table in the database (you could use SqlBulkCopy for this for optimal insert speed). Once it's in there, you could then index the customer_nr field and then run 2 statements:
-- UPDATE existing customers
UPDATE ci
SET ci.firstname = s.firstname,
ci.lastname = s.lastname,
... etc
FROM StagingTable s
INNER JOIN Customer_Info ci ON s.customer_nr = ci.customer_nr
-- INSERT new customers
INSERT Customer_Info (customer_nr, firstname, lastname, ....)
SELECT s.customer_nr, s.firstname, s.lastname, ....
FROM StagingTable s
LEFT JOIN Customer_Info ci ON s.customer_nr = ci.customer_nr
WHERE ci.customer_nr IS NULL
Finally, drop your staging table.
Alternatively, instead of the 2 statements, you could just use the MERGE statement if you are using SQL Server 2008 or later, which allows you to do INSERTs and UPDATEs via a single statement.
If I understand your question correctly - if the customer already exists you want to update their information, and if they don't already exist you want to insert a new row.
I have a lot of problems with hard-coded SQL commands in your code, so I would firstly be very tempted to refactor what you have done. However, to achieve what you want, you will need to execute a SELECT on the primary key, if it returns any results you should execute an UPDATE else you should execute an INSERT.
It would be best to do this in something like a Stored Procedure - you can pass the information to the stored procedure at then it can make a decision on whether to UPDATE or INSERT - this would also reduce the overhead of making several calls for your code to the database (A stored procedure would be much quicker)
AdaTheDev has indeed given the good suggestion.
But in case, you must insert/update from .NET code then you can
Create a stored procedure that will handle insert/update i.e. instead of using a direct insert query as command text, you make a call to stored proc. The SP will check if row exists or not and then update (or insert).
User TableAdapter - but this would be tedious. First you have to setup both insert & update commands. Then you have to query the database to get the existing customer numbers and then update the corresponding rows in the datatable making the Rowstate as Updated. I would rather not go this way.
I am building a hit counter. I have an article directory and tracking unique visitors. When a visitor comes i insert the article id and their IP address in the database. First I check to see if the ip exists for the article id, if the ip does not exist I make the insert. This is two queries -- is there a way to make this one query
Also, I am not using stored procedures I am using regular inline sql
Here are some options:
INSERT IGNORE INTO `yourTable`
SET `yourField` = 'yourValue',
`yourOtherField` = 'yourOtherValue';
from MySQL reference manual: "If you use the IGNORE keyword, errors that occur while executing the INSERT statement are treated as warnings instead. For example, without IGNORE, a row that duplicates an existing UNIQUE index or PRIMARY KEY value in the table causes a duplicate-key error and the statement is aborted.".) If the record doesn't yet exist, it will be created.
Another option would be:
INSERT INTO yourTable (yourfield,yourOtherField) VALUES ('yourValue','yourOtherValue')
ON DUPLICATE KEY UPDATE yourField = yourField;
Doesn't throw error or warning.
Yes, you create a UNIQUE constraint on the columns article_id and ip_address. When you attempt to INSERT a duplicate the INSERT will be refused with an error. Just answered the same question here for SQLite.
IF NOT EXISTS (SELECT * FROM MyTable where IPAddress...)
INSERT...
Not with SQL Server. With T-SQL you have to check for the existence of a row, then use either INSERT or UPDATE as appropriate.
Another option is to try UPDATE first, and then examine the row count to see if there was a record updated. If not, then INSERT. Given a 50/50 chance of a row being there, you have executed a single query 50% of the time.
MySQL has a extension called REPLACE that has the capability that you seek.
The only way I can think of is execute dynamic SQL using the SqlCommand object.
IF EXISTS(SELECT 1 FROM IPTable where IpAddr=<ipaddr>)
--Insert Statement
I agree with Larry about using uniqueness, but I would implement it like this:
IP_ADDRESS, pk
ARTICLE_ID, pk, fk
This ensures that a record is unique hit. Attempts to insert duplicates would get an error from the database.
I would really use procedures! :)
But either way, this will probably work:
Create a UNIQUE index for both the IP and article ID columns, the insert query will fail if they already exist, so technically it'll work! (tested on mysql)
try this (it's a real kludge, but it should work...):
Insert TableName ([column list])
Select Distinct #PK, #valueA, #ValueB, etc. -- list all values to be inserted
From TableName
Where Not Exists
(Select * From TableName
Where PK == #PK)