[d2857c]: System.Data.SQLite / SQLiteKeyReader.cs  Maximize  Restore  History

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/********************************************************
* ADO.NET 2.0 Data Provider for SQLite Version 3.X
* Written by Robert Simpson (robert@blackcastlesoft.com)
*
* Released to the public domain, use at your own risk!
********************************************************/
using System.Collections.Generic;
using System.Data.Common;
using System.Globalization;
namespace System.Data.SQLite
{
/// <summary>
/// This class provides key info for a given SQLite statement.
/// <remarks>
/// Providing key information for a given statement is non-trivial :(
/// </remarks>
/// </summary>
internal sealed class SQLiteKeyReader : IDisposable
{
private bool _isValid;
private KeyInfo[] _keyInfo;
private SQLiteStatement _stmt;
/// <summary>
/// This function does all the nasty work at determining what keys need to be returned for
/// a given statement.
/// </summary>
/// <param name="cnn"></param>
/// <param name="reader"></param>
/// <param name="stmt"></param>
internal SQLiteKeyReader(SQLiteConnection cnn, SQLiteDataReader reader, SQLiteStatement stmt)
{
var catalogs = new Dictionary<string, int>();
var tables = new Dictionary<string, List<string>>();
List<string> list;
var keys = new List<KeyInfo>();
// Record the statement so we can use it later for sync'ing
_stmt = stmt;
// Fetch all the attached databases on this connection
using (DataTable tbl = cnn.GetSchema("Catalogs"))
{
foreach (DataRow row in tbl.Rows)
{
catalogs.Add((string) row["CATALOG_NAME"], Convert.ToInt32(row["ID"], CultureInfo.InvariantCulture));
}
}
// Fetch all the unique tables and catalogs used by the current statement
using (DataTable schema = reader.GetSchemaTable(false, false))
{
foreach (DataRow row in schema.Rows)
{
// Check if column is backed to a table
if (row[SchemaTableOptionalColumn.BaseCatalogName] == DBNull.Value)
continue;
// Record the unique table so we can look up its keys
var catalog = (string) row[SchemaTableOptionalColumn.BaseCatalogName];
var table = (string) row[SchemaTableColumn.BaseTableName];
if (tables.ContainsKey(catalog) == false)
{
list = new List<string>();
tables.Add(catalog, list);
}
else
list = tables[catalog];
if (list.Contains(table) == false)
list.Add(table);
}
// For each catalog and each table, query the indexes for the table.
// Find a primary key index if there is one. If not, find a unique index instead
foreach (var pair in tables)
{
for (int i = 0; i < pair.Value.Count; i++)
{
string table = pair.Value[i];
DataRow preferredRow = null;
using (DataTable tbl = cnn.GetSchema("Indexes", new[] {pair.Key, null, table}))
{
// Loop twice. The first time looking for a primary key index,
// the second time looking for a unique index
for (int n = 0; n < 2 && preferredRow == null; n++)
{
foreach (DataRow row in tbl.Rows)
{
if (n == 0 && (bool) row["PRIMARY_KEY"])
{
preferredRow = row;
break;
}
else if (n == 1 && (bool) row["UNIQUE"])
{
preferredRow = row;
break;
}
}
}
if (preferredRow == null) // Unable to find any suitable index for this table so remove it
{
pair.Value.RemoveAt(i);
i--;
}
else // We found a usable index, so fetch the necessary table details
{
using (DataTable tblTables = cnn.GetSchema("Tables", new[] {pair.Key, null, table}))
{
// Find the root page of the table in the current statement and get the cursor that's iterating it
int database = catalogs[pair.Key];
int rootPage = Convert.ToInt32(tblTables.Rows[0]["TABLE_ROOTPAGE"],
CultureInfo.InvariantCulture);
int cursor = stmt._sql.GetCursorForTable(stmt, database, rootPage);
// Now enumerate the members of the index we're going to use
using (
DataTable indexColumns = cnn.GetSchema("IndexColumns",
new[]
{
pair.Key, null, table,
(string) preferredRow["INDEX_NAME"]
})
)
{
KeyQuery query = null;
var cols = new List<string>();
for (int x = 0; x < indexColumns.Rows.Count; x++)
{
bool addKey = true;
// If the column in the index already appears in the query, skip it
foreach (DataRow row in schema.Rows)
{
if (row.IsNull(SchemaTableColumn.BaseColumnName))
continue;
if ((string) row[SchemaTableColumn.BaseColumnName] ==
(string) indexColumns.Rows[x]["COLUMN_NAME"] &&
(string) row[SchemaTableColumn.BaseTableName] == table &&
(string) row[SchemaTableOptionalColumn.BaseCatalogName] == pair.Key)
{
indexColumns.Rows.RemoveAt(x);
x--;
addKey = false;
break;
}
}
if (addKey)
cols.Add((string) indexColumns.Rows[x]["COLUMN_NAME"]);
}
// If the index is not a rowid alias, record all the columns
// needed to make up the unique index and construct a SQL query for it
if ((string) preferredRow["INDEX_NAME"] != "sqlite_master_PK_" + table)
{
// Whatever remains of the columns we need that make up the index that are not
// already in the query need to be queried separately, so construct a subquery
if (cols.Count > 0)
{
var querycols = new string[cols.Count];
cols.CopyTo(querycols);
query = new KeyQuery(cnn, pair.Key, table, querycols);
}
}
// Create a KeyInfo struct for each column of the index
for (int x = 0; x < indexColumns.Rows.Count; x++)
{
var columnName = (string) indexColumns.Rows[x]["COLUMN_NAME"];
var key = new KeyInfo();
key.rootPage = rootPage;
key.cursor = cursor;
key.database = database;
key.databaseName = pair.Key;
key.tableName = table;
key.columnName = columnName;
key.query = query;
key.column = x;
keys.Add(key);
}
}
}
}
}
}
}
}
// Now we have all the additional columns we have to return in order to support
// CommandBehavior.KeyInfo
_keyInfo = new KeyInfo[keys.Count];
keys.CopyTo(_keyInfo);
}
/// <summary>
/// How many additional columns of keyinfo we're holding
/// </summary>
internal int Count
{
get { return (_keyInfo == null) ? 0 : _keyInfo.Length; }
}
#region IDisposable Members
public void Dispose()
{
_stmt = null;
if (_keyInfo == null) return;
for (int n = 0; n < _keyInfo.Length; n++)
{
if (_keyInfo[n].query != null)
_keyInfo[n].query.Dispose();
}
_keyInfo = null;
}
#endregion
internal void Sync(int i)
{
Sync();
if (_keyInfo[i].cursor == -1)
throw new InvalidCastException();
}
/// <summary>
/// Make sure all the subqueries are open and ready and sync'd with the current rowid
/// of the table they're supporting
/// </summary>
internal void Sync()
{
if (_isValid) return;
KeyQuery last = null;
for (int n = 0; n < _keyInfo.Length; n++)
{
if (_keyInfo[n].query == null || _keyInfo[n].query != last)
{
last = _keyInfo[n].query;
if (last != null)
{
last.Sync(_stmt._sql.GetRowIdForCursor(_stmt, _keyInfo[n].cursor));
}
}
}
_isValid = true;
}
/// <summary>
/// Release any readers on any subqueries
/// </summary>
internal void Reset()
{
_isValid = false;
if (_keyInfo == null) return;
for (int n = 0; n < _keyInfo.Length; n++)
{
if (_keyInfo[n].query != null)
_keyInfo[n].query.IsValid = false;
}
}
internal string GetDataTypeName(int i)
{
Sync();
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetDataTypeName(_keyInfo[i].column);
else return "integer";
}
internal Type GetFieldType(int i)
{
Sync();
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetFieldType(_keyInfo[i].column);
else return typeof (Int64);
}
internal string GetName(int i)
{
return _keyInfo[i].columnName;
}
internal int GetOrdinal(string name)
{
for (int n = 0; n < _keyInfo.Length; n++)
{
if (String.Compare(name, _keyInfo[n].columnName, StringComparison.OrdinalIgnoreCase) == 0) return n;
}
return -1;
}
internal bool GetBoolean(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetBoolean(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal byte GetByte(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetByte(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal long GetBytes(int i, long fieldOffset, byte[] buffer, int bufferoffset, int length)
{
Sync(i);
if (_keyInfo[i].query != null)
return _keyInfo[i].query._reader.GetBytes(_keyInfo[i].column, fieldOffset, buffer, bufferoffset, length);
else throw new InvalidCastException();
}
internal char GetChar(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetChar(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal long GetChars(int i, long fieldOffset, char[] buffer, int bufferoffset, int length)
{
Sync(i);
if (_keyInfo[i].query != null)
return _keyInfo[i].query._reader.GetChars(_keyInfo[i].column, fieldOffset, buffer, bufferoffset, length);
else throw new InvalidCastException();
}
internal DateTime GetDateTime(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetDateTime(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal decimal GetDecimal(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetDecimal(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal double GetDouble(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetDouble(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal float GetFloat(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetFloat(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal Guid GetGuid(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetGuid(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal Int16 GetInt16(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetInt16(_keyInfo[i].column);
else
{
long rowid = _stmt._sql.GetRowIdForCursor(_stmt, _keyInfo[i].cursor);
if (rowid == 0) throw new InvalidCastException();
return Convert.ToInt16(rowid);
}
}
internal Int32 GetInt32(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetInt32(_keyInfo[i].column);
else
{
long rowid = _stmt._sql.GetRowIdForCursor(_stmt, _keyInfo[i].cursor);
if (rowid == 0) throw new InvalidCastException();
return Convert.ToInt32(rowid);
}
}
internal Int64 GetInt64(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetInt64(_keyInfo[i].column);
else
{
long rowid = _stmt._sql.GetRowIdForCursor(_stmt, _keyInfo[i].cursor);
if (rowid == 0) throw new InvalidCastException();
return Convert.ToInt64(rowid);
}
}
internal string GetString(int i)
{
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetString(_keyInfo[i].column);
else throw new InvalidCastException();
}
internal object GetValue(int i)
{
if (_keyInfo[i].cursor == -1) return DBNull.Value;
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.GetValue(_keyInfo[i].column);
if (IsDBNull(i))
return DBNull.Value;
else return GetInt64(i);
}
internal bool IsDBNull(int i)
{
if (_keyInfo[i].cursor == -1) return true;
Sync(i);
if (_keyInfo[i].query != null) return _keyInfo[i].query._reader.IsDBNull(_keyInfo[i].column);
else return _stmt._sql.GetRowIdForCursor(_stmt, _keyInfo[i].cursor) == 0;
}
/// <summary>
/// Append all the columns we've added to the original query to the schema
/// </summary>
/// <param name="tbl"></param>
internal void AppendSchemaTable(DataTable tbl)
{
KeyQuery last = null;
for (int n = 0; n < _keyInfo.Length; n++)
{
if (_keyInfo[n].query == null || _keyInfo[n].query != last)
{
last = _keyInfo[n].query;
if (last == null) // ROWID aliases are treated special
{
DataRow row = tbl.NewRow();
row[SchemaTableColumn.ColumnName] = _keyInfo[n].columnName;
row[SchemaTableColumn.ColumnOrdinal] = tbl.Rows.Count;
row[SchemaTableColumn.ColumnSize] = 8;
row[SchemaTableColumn.NumericPrecision] = 255;
row[SchemaTableColumn.NumericScale] = 255;
row[SchemaTableColumn.ProviderType] = DbType.Int64;
row[SchemaTableColumn.IsLong] = false;
row[SchemaTableColumn.AllowDBNull] = false;
row[SchemaTableOptionalColumn.IsReadOnly] = false;
row[SchemaTableOptionalColumn.IsRowVersion] = false;
row[SchemaTableColumn.IsUnique] = false;
row[SchemaTableColumn.IsKey] = true;
row[SchemaTableColumn.DataType] = typeof (Int64);
row[SchemaTableOptionalColumn.IsHidden] = true;
row[SchemaTableColumn.BaseColumnName] = _keyInfo[n].columnName;
row[SchemaTableColumn.IsExpression] = false;
row[SchemaTableColumn.IsAliased] = false;
row[SchemaTableColumn.BaseTableName] = _keyInfo[n].tableName;
row[SchemaTableOptionalColumn.BaseCatalogName] = _keyInfo[n].databaseName;
row[SchemaTableOptionalColumn.IsAutoIncrement] = true;
row["DataTypeName"] = "integer";
tbl.Rows.Add(row);
}
else
{
last.Sync(0);
using (DataTable tblSub = last._reader.GetSchemaTable())
{
foreach (DataRow row in tblSub.Rows)
{
object[] o = row.ItemArray;
DataRow newrow = tbl.Rows.Add(o);
newrow[SchemaTableOptionalColumn.IsHidden] = true;
newrow[SchemaTableColumn.ColumnOrdinal] = tbl.Rows.Count - 1;
}
}
}
}
}
}
#region Nested type: KeyInfo
/// <summary>
/// Used to support CommandBehavior.KeyInfo
/// </summary>
private struct KeyInfo
{
internal int column;
internal string columnName;
internal int cursor;
internal int database;
internal string databaseName;
internal KeyQuery query;
internal int rootPage;
internal string tableName;
}
#endregion
#region Nested type: KeyQuery
/// <summary>
/// A single sub-query for a given table/database.
/// </summary>
private sealed class KeyQuery : IDisposable
{
private SQLiteCommand _command;
internal SQLiteDataReader _reader;
internal KeyQuery(SQLiteConnection cnn, string database, string table, params string[] columns)
{
using (var builder = new SQLiteCommandBuilder())
{
_command = cnn.CreateCommand();
for (int n = 0; n < columns.Length; n++)
{
columns[n] = builder.QuoteIdentifier(columns[n]);
}
}
_command.CommandText = String.Format(CultureInfo.InvariantCulture,
"SELECT {0} FROM [{1}].[{2}] WHERE ROWID = ?",
String.Join(",", columns), database, table);
_command.Parameters.AddWithValue(null, (long) 0);
}
internal bool IsValid
{
set
{
if (value) throw new ArgumentException();
if (_reader != null)
{
_reader.Dispose();
_reader = null;
}
}
}
#region IDisposable Members
public void Dispose()
{
IsValid = false;
if (_command != null) _command.Dispose();
_command = null;
}
#endregion
internal void Sync(long rowid)
{
IsValid = false;
_command.Parameters[0].Value = rowid;
_reader = _command.ExecuteReader();
_reader.Read();
}
}
#endregion
}
}

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