/// <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)
{
Dictionary <string, int> catalogs = new Dictionary <string, int>();
Dictionary <string, List <string> > tables = new Dictionary <string, List <string> >();
List <string> list;
List <KeyInfo> keys = new List <KeyInfo>();
List <RowIdInfo> rowIds = new List <RowIdInfo>();
// 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
string catalog = (string)row[SchemaTableOptionalColumn.BaseCatalogName];
string 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 (KeyValuePair <string, List <string> > 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 string[] { 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"] == true)
{
preferredRow = row;
break;
}
else if (n == 1 && (bool)row["UNIQUE"] == true)
{
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 string[] { 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 string[] { pair.Key, null, table, (string)preferredRow["INDEX_NAME"] }))
{
//
// NOTE: If this is actually a RowId (or alias), record that now. There should
// be exactly one index column in that case.
//
bool isRowId = (string)preferredRow["INDEX_NAME"] == "sqlite_master_PK_" + table;
KeyQuery query = null;
List <string> cols = new List <string>();
for (int x = 0; x < indexColumns.Rows.Count; x++)
{
string columnName = SQLiteConvert.GetStringOrNull(
indexColumns.Rows[x]["COLUMN_NAME"]);
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] == columnName &&
(string)row[SchemaTableColumn.BaseTableName] == table &&
(string)row[SchemaTableOptionalColumn.BaseCatalogName] == pair.Key)
{
if (isRowId)
{
RowIdInfo rowId = new RowIdInfo();
rowId.databaseName = pair.Key;
rowId.tableName = table;
rowId.column = (int)row[SchemaTableColumn.ColumnOrdinal];
rowIds.Add(rowId);
}
indexColumns.Rows.RemoveAt(x);
x--;
addKey = false;
break;
}
}
if (addKey == true)
{
cols.Add(columnName);
}
}
// 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 (!isRowId)
{
// 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)
{
string[] 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++)
{
string columnName = SQLiteConvert.GetStringOrNull(indexColumns.Rows[x]["COLUMN_NAME"]);
KeyInfo 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);
_rowIdInfo = new RowIdInfo[rowIds.Count];
rowIds.CopyTo(_rowIdInfo);
}
