/// <summary>
/// Reads list of indexes using SHOW INDEX FROM query. Enumerates tables using
/// given restrictions first and then reads indexes for each table.
/// </summary>
/// <param name="connection">The DataConnectionWrapper to be used for enumeration.</param>
/// <param name="restrictions">The restrictions to be putted on the retrieved objects set.</param>
/// <param name="sort">Sort expresion to append after ORDER BY clause.</param>
/// <returns>Returns table with Database Objects which satisfy given restriction.</returns>
protected override DataTable ReadTable(DataConnectionWrapper connection, object[] restrictions, string sort)
{
if (connection == null)
{
throw new ArgumentNullException("connection");
}
DataTable result = PrepareTable();
// Fill restrictions for the tables
object[] tableRestrictions = restrictions;
// If necessary, cut the restrictions
if (restrictions != null && restrictions.Length > 3)
{
tableRestrictions = new object[3];
tableRestrictions[0] = restrictions[0];
tableRestrictions[1] = restrictions[1];
tableRestrictions[2] = restrictions[2];
}
// Read tables
DataTable tables = ObjectDescriptor.EnumerateObjects(connection, TableDescriptor.TypeName, tableRestrictions, sort);
if (tables == null || tables.Rows == null)
{
return(result);
}
// StringBuilder for query
StringBuilder query = new StringBuilder(EnumerateSql);
// Extract indexes for all tables
foreach (DataRow table in tables.Rows)
{
// Truncate query
if (query.Length > EnumerateSql.Length)
{
query.Remove(EnumerateSql.Length, query.Length - EnumerateSql.Length);
}
// Write table idintifier
QueryBuilder.WriteIdentifier(
DataInterpreter.GetStringNotNull(table, TableDescriptor.Attributes.Schema),
DataInterpreter.GetStringNotNull(table, TableDescriptor.Attributes.Name),
query);
// Execute query to select indexes
DataTable indexes = connection.ExecuteSelectTable(query.ToString());
if (indexes == null || indexes.Rows == null)
{
Debug.Fail("Failed to read indexes using query:\n" + query.ToString());
continue;
}
// Fetch data
FetchData(restrictions, table, indexes, result);
}
// Accept changes for result
result.AcceptChanges();
// Return resulting table
return(result);
}