System.Data.ProviderBase.AbstractDataReader.InitKeyInfo C# (CSharp) Method

		private void InitKeyInfo(DataRow row, DatabaseMetaData dbMetaData, String catalog, String schema, String table) {
			string column = (string)row [(int)SCHEMA_TABLE.BaseColumnName];

			row [(int)SCHEMA_TABLE.IsUnique] = false;
			row [(int)SCHEMA_TABLE.IsKey] = false;
			row [(int)SCHEMA_TABLE.IsIdentity] = false;
			row [(int)SCHEMA_TABLE.IsRowVersion] = false;

			if ((_command.Behavior & CommandBehavior.KeyInfo) == 0)
				return;

			if(table == null || column == null || dbMetaData == null)
				return;

			ResultSet versionCol = dbMetaData.getVersionColumns(catalog, schema, table);
			try {
				while(versionCol.next()) {
					if(versionCol.getString("COLUMN_NAME") == column) {
						if (DatabaseMetaData__Finals.versionColumnPseudo == versionCol.getShort("PSEUDO_COLUMN")) {
							row [(int)SCHEMA_TABLE.IsIdentity] = true;
							row [(int)SCHEMA_TABLE.IsRowVersion] = true;
						}
					}
				}
			}
			finally {
				versionCol.close();
			}

			ResultSet primaryKeys = dbMetaData.getPrimaryKeys(catalog,schema,table);
			bool primaryKeyExists = false;
			int columnCount = 0;
			try {
				while(primaryKeys.next()) {
					columnCount++;
					if(primaryKeys.getString("COLUMN_NAME") == column) {
						row [(int)SCHEMA_TABLE.IsKey] = true;
						primaryKeyExists = true;
					}
				}
				// column constitutes a key by itself, so it should be marked as unique 
				if ((columnCount == 1) && (((bool)row [(int)SCHEMA_TABLE.IsKey]) == true)) {
					row [(int)SCHEMA_TABLE.IsUnique] = true;
				}
			}
			finally {
				primaryKeys.close();
			}

			ResultSet indexInfoRes = dbMetaData.getIndexInfo(catalog,schema,table,true,false);
			string currentIndexName = null;
			columnCount = 0;
			bool belongsToCurrentIndex = false;
			bool atFirstIndex = true;
			bool uniqueKeyExists = false;
			try {
				while(indexInfoRes.next()) {
					if (indexInfoRes.getShort("TYPE") ==  DatabaseMetaData__Finals.tableIndexStatistic) {
						// index of type tableIndexStatistic identifies table statistics - ignore it
						continue;
					}
					
					uniqueKeyExists = true;
					string iname = indexInfoRes.getString("INDEX_NAME");
					if (currentIndexName == iname) {
						// we're within the rows of the same index 
						columnCount++;
					}
					else {
						// we jump to row of new index 
						if (belongsToCurrentIndex && columnCount == 1) {
							// there is a constraint of type UNIQUE that applies only to this column
							row [(int)SCHEMA_TABLE.IsUnique] = true;
						}

						if (currentIndexName != null) {
							atFirstIndex = false;
						}
						currentIndexName = iname;
						columnCount = 1;
						belongsToCurrentIndex = false;
					}

					if(indexInfoRes.getString("COLUMN_NAME") == column) {
						// FIXME : this will cause "spare" columns marked as IsKey. Needs future investigation.
						// only the first index we met should be marked as a key
						//if (atFirstIndex) {
							row [(int)SCHEMA_TABLE.IsKey] = true;
						//}
						belongsToCurrentIndex = true;						
					}
				}
				// the column appears in the last index, which is single-column
				if (belongsToCurrentIndex && columnCount == 1) {
					// there is a constraint of type UNIQUE that applies only to this column
					row [(int)SCHEMA_TABLE.IsUnique] = true;
				}
			}
			finally {
				indexInfoRes.close();
			}			

			if(!primaryKeyExists && !uniqueKeyExists) {
				ResultSet bestRowId = dbMetaData.getBestRowIdentifier(catalog, schema, table, DatabaseMetaData__Finals.bestRowTemporary, false);
				try {
					while(bestRowId.next()) {
						if(bestRowId.getString("COLUMN_NAME") == column)
							row [(int)SCHEMA_TABLE.IsKey] = true;
					}
				}
				finally {
					bestRowId.close();
				}
			}
		}