NOTE: This is the simple version of my previous question that SHOULD have been written.
I have two tables in the same SQL Server database, TestTable and TestTable2. Neither has a primary key. Each have two columns,
TestInt (int)
TestString (varchar(50))
There is data in TestTable2, while TestTable is empty. I want to copy the contents of one into the other, via C#. (I know this can be done in SQL, but humor me here.)
Here is the code I've written to do the job, using a SqlDataAdapter object...
// Data in TestTable2, nothing in TestTable.
private static void Main(string[] args)
{
SqlConnection conn = /* CONNECTION CREATION CODE */
string sqlQuery = "SELECT * FROM TestTable2";
DataTable payload = /* SIMPLE QUERY CODE USING sqlQuery */
// CODE CHECKPOINT #1
sqlQuery = "SELECT * FROM TestTable";
SqlCommand sCmd = new SqlCommand(sqlQuery, conn);
SqlDataAdapter sDA = new SqlDataAdapter(sCmd);
DataSet dataSet = new DataSet();
conn.Open();
sDA.Fill(dataSet);
conn.Close();
for (int i = 0; i < payload.Rows.Count; i++)
{
dataSet.Tables[0].ImportRow(payload.Rows[i]);
}
// CODE CHECKPOINT #2
SqlCommandBuilder cb = new SqlCommandBuilder(sDA);
conn.Open();
sDA.Update(dataSet);
conn.Close();
}
The problem is that this code is not working. If I were to check the contents of DataTable 'payload' at Checkpoint #1, I see 4 rows, while there are 0 rows in dataSet.Tables[0]. If I then check the contents of 'dataSet' at Checkpoint #2, I see 4 rows in dataSet.Tables[0]! However, at the end of the program, none of the rows from TestTable2 have made it into TestTable.
In other words, C# is moving the data between the DataTables, but it is having no affect on the tables themselves.
I've found that adding newly created rows
DataRow row = DataSet.DataTable.NewRow(...);
...
dataSet.Tables[i].Rows.Add(row);
into the destination DataSet works with SqlDataAdapter.Update, but that's not appropriate in this case, as you cannot use DataTable.Rows.Add on a row held by a separate DataTable. Hence, my problem, as this has rendered me incapable of transfering data from one table to another, especially in cases where large numbers of column are involved, rendering explicit SQL commands very clunky.
Is there something I'm missing in this code that I'm not seeing? If so, what is it?
Thanks.
Try DataSet.AcceptChanges() before updating data to the DB. Also, check, what the DataSet.GetChanges() method returns. It should not be an empty DataSet.
Finally, I have found the solution here:
importrow --> update fails
The ultimate answer is a translation of the link provided by platon. However, I'm including the explicit code here for easier future reference.
Basically, ImportRow doesn't always set the dirty bit for the added rows. As a result, SqlDataAdapter.Update won't necessarily move the changes to SQL since it doesn't recognize the new rows as changed data. To insure that the dirty bit is set, you need to call DataTable.Rows.Add, but as mentioned this cannot be called using the row of another table as a parameter.
What to do? Don't use the row as a parameter to Add(). Instead, use the object[] ItemArray...
for(int i = 0 ; i < srcTable.Rows.Count ; i++)
{
destTable.Rows.Add(srcTable.Rows[i].ItemArray);
}
...
SqlCommandBuilder sCB = new SqlCommandBuilder(adapter);
adapter.Update(dataSet);
Related
I have been trying to use OleDbDataAdapter to update a DataTable but got confused about the commands.
Since I sometimes get info from diffrent tables I can't use a CommandBuilder.
So I have tried to create the commands on my on but found it hard with the parameters.
DataTable.GetChanges returns rows that needs to use an INSERT or an UPDATE command - I guess I can't distinct between them.
I need you to complete the following:
DataTable dt = new DataTable();
OleDbDataAdapter da = new OleDbDataAdapter();
// Here I create the SELECT command and pass the connection.
da.Fill(dt);
// Here I make changes (INSERT/UPDATE) to the DataTable (by a DataGridView).
da.UpdateCommand = new OleDbCommand("UPDATE TABLE_NAME SET (COL1, COL2, ...) VALUES (#newVal1, #newVal2, ...) WHERE id=#id"); // How can I use the values of the current row (that the da is updating) as the parameters (#newVal1, #newVal2, id....)?
Thank you very much!
The data adapter can work in conjunction with the datatable. As such, I've actually wrapped mine together into a class and works quite well. Aside from the complexities of my stuff, here's a snippet that might help you along. When adding a parameter, you can identify the column source that the data is coming from FROM the DataTable. This way, when a record is internally identified as "Added" or "Updated" (or "Deleted"), when you build your SQL Insert/Update/Delete commands, it will pull the data from the columns from the respective rows.
For example. Say I have a DataTable, primary Key is "MyID" and has columns "ColX, ColY, ColZ". I create my DataAdapter and build out my select, update, delete commands something like... (? is a place-holder for the parameters)
DataAdapter myAdapter = new DataAdapter()
myAdapter.SelectCommand = new OleDbCommand();
myAdapter.InsertCommand = new OleDbCommand();
myAdapter.UpdateCommand = new OleDbCommand();
myAdapter.DeleteCommand = new OleDbCommand();
myAdapter.SelectCommand.CommandText = "select * from MyTable where MyID = ?";
myAdapter.InsertCommand.CommandText = "insert into MyTable ( ColX, ColY, ColZ ) values ( ?, ?, ? )";
myAdapter.UpdateCommand.CommandText = "update MyTable set ColX = ?, ColY = ?, ColZ = ? where MyID = ?";
myAdapter.DeleteCommand.CommandText = "delete from MyTable where MyID = ?";
Now, each has to have their respective "Parameters". The parameters have to be addded in the same sequence as their corresponding "?" place-holders.
// Although I'm putting in bogus values for preparing the parameters, its just for
// data type purposes. It does get changed through the data adapter when it applies the changes
OleDbParameter oParm = new OleDbParameter( "myID", -1 );
oParm.DbType = DbType.Int32;
oParm.SourceColumn = "myID"; // <- this is where it looks back to source table's column
oParm.ParameterName = "myID"; // just for consistency / readability reference
myAdapter.SelectCommand.Parameters.Add( oParm );
do similar for rest of parameters based on their types... char, int, double, whatever
Again, I have like a wrapper class that handles managment on a per-table basis... in brief
public myClassWrapper
{
protected DataTable myTable;
protected DataAdapter myAdapter;
... more ...
protected void SaveChanges()
{
}
}
Its more complex than just this, but during the "SaveChanges", The datatable and dataAdapter are in synch for their own purposes. Now, flushing the data. I check for the status of the table and then you can pass the entire table to the dataAdapter for update and it will cycle through all changed records and push respective changes. You'll have to trap for whatever possible data errors though.
myAdapter.Update( this.MyTable );
As it finds each "changed" record, it pulls the values from the Column Source as identified by the parameter that is found in the table being passed to the adapter for processing.
Hopefully this has given you a huge jump on what you are running into.
---- COMMENT PER FEEDBACK ----
I would put your update within a try/catch, and step into the program to see what the exception is. The message adn/or inner exception of the error might give more info. However, try to simplify your UPDATE to only include a FEW fields with the WHERE "Key" element.
Additionally, and I oopsed, missed this from first part answer. You might have to identify the datatable's "PrimaryKey" column. To do so, its a property of the DataTable that expects and array of columns that represent the primary key for the table. What I did was...
// set the primary key column of the table
DataColumn[] oCols = { myDataTbl.Columns["myID"] };
myDataTbl.PrimaryKey = oCols;
I would comment out your full update string and all its parameters for your UPDATE. Then, build it with just as simple as my sample of only setting 2-3 columns and the where clause
myAdapter.UpdateCommand.CommandText = "update MyTable set ColX = ?, ColY = ? where MyID=?";
Add Parameter object for "X"
Add Parameter object for "Y"
Add Parameter object for "MyID"
Pick fields like int or char so they have the least probability of problems for data type conversions, then, once that works, try adding all your "int" and "character" columns... then add any others. Also, which database are you going against. SOME databases don't use "?" as placeholder in the command but use "named" parameters, some using
"actualColumn = #namedCol"
or even
"actualColumn = :namedCol"
Hope this gets you over the hump...
You could use the String.Format Method to replace the #newVal1, #newVal2, ... in your code, like this da.UpdateCommand = new OleDbCommand(String.Format("UPDATE TABLE_NAME SET (COL1, COL2, ...) VALUES ({0}, {1}, ...) WHERE id=#id",OBJECT_ARRAY_CONTAINING_VALUES_FROM_THEDG));
[Eidt per comment]
To handle the row[0], row[1] you need a loop like:
for(i=0; i<rows.Count; i++)
{
da.UpdateCommand = new OleDbCommand(String.Format("UPDATE...",row[i]);
da.Update(dt);
}
This code snippet is throwing an error:
Update unable to find TableMapping['Table'] or DataTable 'Table'.) on adapter.Update(ds); line
Why it is throwing this type of error?
SqlConnection con = new SqlConnection();
con.ConnectionString = connectionString();
DataSet ds = new DataSet();
string strQuery = "SELECT * FROM Cars";
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand(strQuery, con);
SqlCommandBuilder builder = new SqlCommandBuilder(adapter);
adapter.Fill(ds, "Cars");
//Code to modify data in the DataSet
ds.Tables["Cars"].Rows[0]["Brand"] = "NewBrand";
adapter.UpdateCommand = builder.GetUpdateCommand();
adapter.Update(ds);
Use
adapter.Update(ds, "Cars");
instead.
I have tested it. I got the same error without and it works if i specify the tablename. However, i must admit that i yet don't know why the DataAdapter needs to know the table-name since it has all informations it needs. If i useds.GetChanges i get one row with the correct table-name.
Update I have found nothing on MSDN but finally found it in the source(ILSpy). Here is the implementation of DBDataAdapter.Update(DataSet):
public override int Update(DataSet dataSet)
{
return this.Update(dataSet, "Table");
}
So if you don't specify a table, the table-name "Table" is used and if you've specified a table-name other than that you'll get this error, that's really strange!
I assume that the reason for this is that the DataAdapter cannot call GetChanges to determine the table to update for two reasons:
It would be inefficient since it needs to loop all tables and all of their rows to find rows with a RowState != Unchanged
It's possible that multiple tables needs to be updated since they contain changed rows. That is not supported via DataAdapter. Hence DataAdapter.Update(DataSet) assumes the default name "Table" as table-name.
Edit: However, maybe someone can explain me why the DataAdapter doesn't use DataSet.Tables[0].TableName instead.
So in general it seems to be best practise to specify the name of the table you want to update.
It's because .NET cannot assume that the table name in the DataSet/DataTable is identical to the database table. Thus .NET warns you about it.
To solve it you need to add a mapping to the DataAdapter:
da.TableMappings.Add("TableNameInDb", "TableNameInTheDataSet");
However, even if you have specified a name in the DataSet or the DataSource it still doesn't work, since the adapter seems to forget the name.
I only got it working by using:
da.TableMappings.Add("Table", "TableNameInDb");
I agree with jgauffin and I will only explain it with more text.
First, I must explain how TableMapping works. If we don't specify TableMappings with SqlDataAdapter (SqlDataAdapter that will fill our DataSet) then by default the first table will be named "Table", the second will be named "Table1", the third will be named "Table2" etc.
So, when we want to name DataTable in DataSet, we use it like this:
System.Data.DataSet myDataSet = new System.Data.DataSet();
using (System.Data.SqlClient.SqlDataAdapter dbAdapter = new System.Data.SqlClient.SqlDataAdapter(dbCommand))
{
dbAdapter.TableMappings.Add("Table", "Cars");
dbAdapter.TableMappings.Add("Table1", "Trucks");
//...
dbAdapter.Fill(myDataSet);
}
And only then we can modify it like this:
myDataSet.Tables["Cars"].Rows[0]["Brand"] = "Toyota";
myDataSet.Tables["Trucks"].Rows[0]["Brand"] = "MAN";
I am trying to use MySqlDatAdapter to update a MySql table. But, the table never updates!!! I did this before but with SQL server. Is there anything else that is specific to MySql that I am missing in my code?
DataTable myTable = new DataTable("testtable");
MySqlConnection mySqlCon = new MySqlConnection(ConfigurationManager.ConnectionStrings["DBConStr"].ConnectionString);
MySqlCommand mySqlCmd = new MySqlCommand("SELECT * FROM testtable WHERE Name = 'Tom'");
mySqlCmd.Connection = mySqlCon;
MySqlDataAdapter adapter = new MySqlDataAdapter(mySqlCmd);
MySqlCommandBuilder myCB = new MySqlCommandBuilder(adapter);
adapter.UpdateCommand = myCB.GetUpdateCommand();
mySqlCon.Open();
adapter.Fill(myTable);
myTable.Rows[0]["Name"] = "Was Tom";
myTable.AcceptChanges();
adapter.Update(myTable);
mySqlCon.Close();
Thanks
Remove myTable.AcceptChanges() before the update. Othwerwise that will set all rows RowState to Unchanged, hence the DataAdapter will not know that something was changed.
adapter.Update(myTable) will call AcceptChanges itself after the update is finished.
So...
myTable.Rows[0]["Name"] = "Was Tom";
//myTable.AcceptChanges();
adapter.Update(myTable);
My some one need to look into the following solution; In other scenario people may need different solution. Even Don't do any manipulation with Datatable when you Debug at Run-time like this,
myTable.GetChanges(); // Return Any of Chnages Made without applying myTable.Accepchanges()
myTable.GetChanges(DataRowState.Added); // Return added rows without applying myTable.Accepchanges()
myTable.GetChanges(DataRowState.Deleted);
myTable.GetChanges(DataRowState.Detached);
myTable.GetChanges(DataRowState.Modified);
myTable.GetChanges(DataRowState.Unchanged);
You may get Data According to the above commands. So better try to debug before you pass the datatable to update or insert or delete command.
If myTable.GetChanges() return null then you can SetAdded() or SetModified() back to your DataTable;
foreach(DataRow row in myTable.Rows)
{
row.SetAdded(); // For Insert Command
row.SetModified(); // For Update Command
}
Could somebody take a quick peek at my ado.net code? I am trying to update the row from a dataset, but it just isn't working. I am missing some elemental piece of the code, and it is just eluding me. I have verified that the DataRow actually has the correct data in it, so the row itself is accurate.
Many thanks in advance.
try
{
//basic ado.net objects
SqlDataAdapter dbAdapter = null;
DataSet returnDS2 = new DataSet();
//a new sql connection
SqlConnection myConn = new SqlConnection();
myConn.ConnectionString = "Server=myserver.mydomain.com;"
+ "Database=mydatabase;"
+ "User ID=myuserid;"
+ "Password=mypassword;"
+ "Trusted_Connection=True;";
//the sqlQuery
string sqlQuery = "select * from AVLUpdateMessages WHERE ID = 21";
//another ado.net object for the command
SqlCommand cmd = new SqlCommand();
cmd.Connection = myConn;
cmd.CommandText = sqlQuery;
//open the connection, execute the SQL statement and then close the connection.
myConn.Open();
//instantiate and fill the sqldataadapter
dbAdapter = new SqlDataAdapter(cmd);
dbAdapter.Fill(returnDS2, #"AVLUpdateMessages");
//loop through all of the rows; I have verified that the rows are correct and returns the correct data from the db
for (int i = 0; i <= returnDS2.Tables[0].Rows.Count - 1; i++)
{
DataRow row = returnDS2.Tables[0].Rows[i];
row.BeginEdit();
row["UpdatedText"] = #"This is a test...";
row.EndEdit();
}
//let's accept the changes
dbAdapter.Update(returnDS2, "AVLUpdateMessages");
returnDS2.AcceptChanges();
myConn.Close();
}
I think you need an update query in your data adapter. I know, this sucks... Alternatively you can use CommandBuilder class to automatically generate queries for CRUD operations.
example at: http://www.programmersheaven.com/2/FAQ-ADONET-CommandBuilder-Prepare-Dataset
You might be able to use SqlCommandBuilder to help out. After the Fill call, add the following statement. That will associate a command builder with the data adapter and (if there is a primary key available) it should generate the update statement for you. Note that there is some expense behind the command builder. It may not be much relative to everything else, but it does involve looking at schema information (to get primary key information, field names, field types, etc.) for the table and generating INSERT, DELETE, and UPDATE statements involving all fields in the table.
SqlCommandBuilder cb = new SqlCommandBuilder(dbAdapter);
Wait, why not something like
update AVLUpdateMessages set UpdatedText = 'This is a test...' where id = 21
If you're picking through all the rows of a table to update one at a time, you're probably doing it wrong. SQL is your friend.
I am attempting to update a simple ms access database. I get an Exception on certain tables that, after searching, I found Microsoft Support - Syntax Error. I believe it means that one of the column names uses a reserved word. This seems to be the case, since all the tables update except the ones with "GUID" as one of the column names, a reserved word. This page also states that I should be using a OleDbAdapter and DataSet, which should solve the problem. Unfortunately I cannot change the name of the column. That is beyond my control, so I have to work with what is given me.
I haven't had to do work with databases much, and everything I know I've learned from examples from the internet (probably bad ones at that). So what is the proper way to update a database using OleDbAdapter and dataSet?
I don't think I should be using DataTable or OleDbCommandBuilder, and I believe the solution has something to do with parameters. But my googleing skills are weak.
OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; " +
Data Souce=" + source);
conn.Open();
OleDbAdapter adapter = new OleDbDataAdapter("SELECT * From " + table, conn);
OleDbCommandBuiler cmdBuiler = new OleDbCommandBuilder(adapter);
DataSet = new DatSet();
adapter.InsertCommand = cmdBuilder.GetInertCommand(true); // Is this necessary?
adapter.Fill( dataSet, table);
DataTable dataTable = dataSet.Tables[table]; // Do I need a DataTable?
DataRow row = dataTable.
row [ attribute ] = field; // Do this for all attributes/fields. I think this is wrong.
dataTable.rows.Add(row);
adapter.Update(dataTable); //<--"Syntax error in INSERT INTO statement." Exception
The problem may be that the column names (especially those whose name are reserved words) should be surrounded by square brackets. The OleDbCommandBuilder, when it creates its own InsertCommand, doesn't surround the names with brackets, so a solution is to manually define the OleDbDataAdapter's InsertCommand:
adapter.InsertCommand = new OleDbCommand(String.Format("INSERT INTO {0} ([GUID], [fieldName]) Values (#guid,#fieldName);", table), conn);
Defining parameters for each column and then manually adding the parameter's values;
adapter.InsertCommand.Parameters.Add(new OleDbParameter("#guid",row["GUID"]));
So summing up, for the tables which have a column named "GUID", you should try something like the following:
OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;" +
"Data Souce=" + source);
conn.Open();
OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * From " + table, conn);
OleDbCommandBuilder cmdBuilder = new OleDbCommandBuilder(adapter);
adapter.InsertCommand = new OleDbCommand(String.Format("INSERT INTO {0} ([GUID], [fieldName]) Values (#guid,#fieldName);", table), conn);
DataTable dataTable = new DataTable(table);
adapter.Fill( dataTable);
DataRow row = dataTable.NewRow();
row [ fieldName ] = fieldValue;
// eg: row [ "GUID" ] = System.Guid.NewGuid().ToString(); // Do this for all attributes/fields.
dataTable.Rows.Add(row);
adapter.InsertCommand.Parameters.Add(new OleDbParameter("#fieldName",row[fieldName]));
// eg: adapter.InsertCommand.Parameters.Add(new OleDbParameter("#guid",row["GUID"]));
adapter.Update(dataTable);
As to problem #1. Try doing a full qualification of the column name i.e. table.columnName (that fixes the problem in MySQL so maybe it does in Access) also, try putting [ ] around the column name.
Select * is usually a poor option to specifying the column names and using aliases. For example use Select Column1 as 'Column1', Column2 as 'Column2' ....
this makes working with your dataset and datatable much easier as you can access the column by its alias instead of by column indexes.
I find that the DataAdapter is much more useful for filling datasets than for actually modifying a database. I recommend something like:
string updateQuery = "Update ..... Where ...."; //do your magic here
OldDbcommand command = new OleDbCommand(updateQuery);
command.Connection = conn;
conn.Open();
con.ExecuteNonQuery();
conn.Close();
You could fill your dataset with the adapter and then do as I just did to execute your update commands on the DB.
A good place to start would be using DataSetDesigner and Typed DataSets to start
try this walk through : http://msdn.microsoft.com/en-us/library/ms171893(v=vs.80).aspx
A good longterm approach is to use Sql Server Express instead, then you'll have a choice of using : Entity Framework, Linq To Sql or Still keep using the DataSetDesigner and Typed DataSets.