how to set the query timeout from SQL connection string

Question

No. It's per command, not per connection.

Edit, May 2013

As requested in comment:

• SQLCommand.CommandTimeout for command execution
• There is no matching SQLConnection property (the questions says not the SqlConnection.ConnectionTimeout property

Some more notes about commands and execution time outs in SQL Server (DBA.SE). And more SO stuff: What happens to an uncommitted transaction when the connection is closed?

See:- ConnectionStrings content on this subject. There is no default command timeout property.

You can only set the connection timeout on the connection string, the timeout for your query would normally be on the command timeout. (Assuming we are talking .net here, I can't really tell from your question).

However the command timeout has no effect when the command is executed against a context connection (a SqlConnection opened with "context connection=true" in the connection string).

Only from code:

namespace xxx.DsXxxTableAdapters {
    partial class ZzzTableAdapter
    {
        public void SetTimeout(int timeout)
        {
            if (this.Adapter.DeleteCommand != null) { this.Adapter.DeleteCommand.CommandTimeout = timeout; }
            if (this.Adapter.InsertCommand != null) { this.Adapter.InsertCommand.CommandTimeout = timeout; }
            if (this.Adapter.UpdateCommand != null) { this.Adapter.UpdateCommand.CommandTimeout = timeout; }
            if (this._commandCollection == null) { this.InitCommandCollection(); }
            if (this._commandCollection != null)
            {
                foreach (System.Data.SqlClient.SqlCommand item in this._commandCollection)
                {
                    if (item != null)
                    { item.CommandTimeout = timeout; }
                }
            }
        }
    }
 
    //....
 
 }