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#ifndef QUERYEXECUTORCOLUMNS_H
#define QUERYEXECUTORCOLUMNS_H
#include "queryexecutorstep.h"
#include "selectresolver.h"
/**
* @brief Assigns unique alias names for all result columns.
*
* This step replaces result columns of the SELECT query.
* It's performed only if last query is the SELECT, otherwise it does nothing.
*
* It works on subselects first, then goes towards outer SELECTs.
*
* Star operator ("all columns") is replaced by list of columns and each column gets alias.
*
* If result column comes from subselect and the subselect was already covered by this step,
* then the column does not get new alias, instead the existing one is used.
*
* While generating alias names, this step also finds out details about columns: source database, source table
* column contraints, etc. Those informations are stored using generated alias name as a key.
*
* Some columns can be defined as not editable, because of various reasons: QueryExecutor::ColumnEditionForbiddenReason.
* Those reasons are defined in this step.
*/
class QueryExecutorColumns : public QueryExecutorStep
{
Q_OBJECT
public:
bool exec();
private:
/**
* @brief Transforms SelectResolver's columns into QueryExecutor's columns.
* @param resolvedColumn Result columns resolved by SelectResolver.
* @return Converted column.
*
* QueryExecutor understands different model of result columns than SelectResolver.
* Converted columns are later used by other steps and it's also returned from QueryExecutor as an information
* about result columns of the query.
*/
QueryExecutor::ResultColumnPtr getResultColumn(const SelectResolver::Column& resolvedColumn);
/**
* @brief Generates result column object with proper alias name.
* @param resultColumn Original result column from the query.
* @param col Original result column as resolved by SelectResolver.
* @param rowIdColumn Indicates if this is a call for ROWID column added by QueryExecutorRowId step.
* @return Result column object ready for rebuilding tokens and detokenizing.
*/
SqliteSelect::Core::ResultColumn* getResultColumnForSelect(const QueryExecutor::ResultColumnPtr& resultColumn, const SelectResolver::Column& col, QSet<QString>& usedAliases);
/**
* @brief Translates attach name into database name.
* @param dbName Attach name.
* @return Database name as registered in DbManager, or \p dbName if given name was not resolved to any registered database.
*/
QString resolveAttachedDatabases(const QString& dbName);
/**
* @brief Checks if given alias name belongs to ROWID result column.
* @param alias Alias name to check.
* @return true if the alias belongs to ROWID column, or false otherwise.
*/
bool isRowIdColumnAlias(const QString& alias);
bool isRowIdColumn(const QString& columnAlias);
QStringList rowIdColNames;
};
#endif // QUERYEXECUTORCOLUMNS_H
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