//we need to do the work around. http://www.sqlite.org/faq.html#q11
public IEnumerable <string> CreateSqlStatements(AlterTableCommand command)
{
string fullTableName = command.Name;
string tempTableName = fullTableName + "_" + Guid.NewGuid().ToString("N");
yield return(StatementUtil.CreateTempTable(tempTableName, fullTableName));
//modify all the references to the old table to go to the new table
//drop the old table
yield return(StatementUtil.DropTable(fullTableName));
//create newTable and insert the data, add and drop indices
foreach (string statement in CreateNewTableCopyInDataAndCreateIndices(command, tempTableName))
{
yield return(statement);
}
//change them all back!
//drop the tempTable
yield return(StatementUtil.DropTable(tempTableName));
}
private IEnumerable <string> CreateNewTableCopyInDataAndCreateIndices(AlterTableCommand command, string tempTable)
{
string fullTableName = command.Name;
//we'll use this to create the insert into later
string[] originalColumns = CreateTableNode.ColumnDefinitions.Select(i => i.ColumnName).ToArray();
CreateTableNode = IncorporateAlterationsInCreateNode(command, CreateTableNode);
var visitor = new TreeStringOutputVisitor();
yield return(CreateTableNode.Accept(visitor).ToString());
string[] finalSetOfColumns =
originalColumns.Where(i => command.TableCommands.OfType <DropColumnCommand>().All(j => j.ColumnName != i))
.ToArray();
// this can only be the ones in the ORIGINAL table that we want to copy, i.e. don't copy in deleted columns
yield return(StatementUtil.InsertInto(fullTableName, finalSetOfColumns, tempTable));
//let's figure out our final indexes
IncorporateAlterationsInIndexNodes(CreateIndexNodes, fullTableName, command.TableCommands, finalSetOfColumns);
var indexNodeVisitor = new TreeStringOutputVisitor();
foreach (CreateIndexNode indexNode in CreateIndexNodes)
{
yield return(indexNode.Accept(indexNodeVisitor).ToString());
}
}
/// <summary>
/// returns null if something if we don't have ones we can do natively
/// </summary>
/// <param name="command"></param>
/// <returns></returns>
public IEnumerable <string> CreateSqlStatements(AlterTableCommand command)
{
if (!command.TableCommands.All(i => i is AddColumnCommand || i is AddIndexCommand || i is DropIndexCommand))
{
// we have non Native Alterations to make
yield break;
}
var visitor = new TreeStringOutputVisitor();
foreach (var alterCommand in command.TableCommands)
{
if (alterCommand is AddColumnCommand)
{
var addColumn = alterCommand as AddColumnCommand;
yield return
(StatementUtil.AddColumn(command.Name,
addColumn.CreateColumnDefNode().Accept(visitor).ToString()));
}
else if (alterCommand is AddIndexCommand)
{
var addIndexCommand = alterCommand as AddIndexCommand;
yield return(StatementUtil.AddIndex(addIndexCommand.IndexName, addIndexCommand.TableName, addIndexCommand.ColumnNames));
}
else if (alterCommand is DropIndexCommand)
{
var dropIndexCommand = alterCommand as DropIndexCommand;
yield return(StatementUtil.DropIndex(dropIndexCommand.IndexName));
}
}
}
