CODEWITHSUNDEEP
c#sql
malay
malay

Reputation: 1452

How to perform batch update in Sql through C# code

I want to update multiple rows like below 

update mytable set s_id = {0} where id = {1}

(Here s_id is evaluated based on some complex logic).
For performance reason, updates should happen in batches. Is there any way to batch the update statements and execute the batch through single execute statements? I know in JAVA we can do this through JDBC. Is there similar way in C#?

Thanks in advance

Upvotes: 14

Views: 31960

Answers (4)

AdaTheDev
AdaTheDev

Reputation: 147234

Yes, you can use an SqlDataAdapter.

The SqlDataAdapter has InsertCommand and UpdateCommand properties which allow you to specify an SQLCommand to use to insert new rows into the database and an SqlCommand to update rows in the database respectively.

You can then pass a DataTable to the Update method of the dataadapter, and it will batch up the statements to the server - for rows in the DataTable that are new rows, it executes the INSERT command, for modified rows it executes the UPDATE command.

You can define the batch size using the UpdateBatchSize property.

This approach allows you to deal with large volumes of data, and allows you to nicely handle errors in different ways, i.e. if an error is encountered with a particular update, you can tell it to NOT throw an exception but to carry on with the remaining updates by setting the ContinueUpdateOnError property.

Upvotes: 22

Jeff Sternal
Jeff Sternal

Reputation: 48583

Yes, you can build a plain-text SQL command (parameterized for security), like this:

SqlCommand command = new SqlCommand();
// Set connection, etc.
for(int i=0; i< items.length; i++) {
    command.CommandText += string.Format("update mytable set s_id=@s_id{0} where id = @id{0};", i);
    command.Parameters.Add("@s_id" + i, items[i].SId);
    command.Parameters.Add("@id" + i, items[i].Id);
}
command.ExecuteNonQuery();

Upvotes: 15

Rob
Rob

Reputation: 45771

Use a StringBuilder (System.Text.StringBuilder) to build your Sql, such as:

StringBuilder sql = new StringBuilder();
int batchSize = 10;
int currentBatchCount = 0;
SqlCommand cmd = null; // The SqlCommand object to use for executing the sql.
for(int i = 0; i < numberOfUpdatesToMake; i++)
{
  int sid = 0; // Set the s_id here
  int id = 0; // Set id here
  sql.AppendFormat("update mytable set s_id = {0} where id = {1}; ", sid, id);

  currentBatchCount++;
  if (currentBatchCount >= batchSize)
  {
    cmd.CommandText = sql.ToString();
    cmd.ExecuteNonQuery();
    sql = new StringBuilder();
    currentBatchCount = 0;
  }
}

Upvotes: 3

David Morton
David Morton

Reputation: 16505

Create a set of those updates (with the id's filled in), separate them by semicolon in one string, set the resulting string to a SqlCommand's CommandText property, then call ExecuteNonQuery().

Upvotes: 0

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