MDQuery Class Reference

#include <metadata_query.h>

Inheritance diagram for MDQuery:

Public Member Functions
	MDQuery (int limit=-1, int offset=0, MDLabel orderLabel=MDL_OBJID, bool asc=true)
virtual	~MDQuery ()
String	orderByString () const
String	limitString () const
String	whereString () const
virtual String	queryStringFunc () const

Public Attributes
int	limit
	If distint of -1 the results will be limited to this value. More...
int	offset
	If distint of 0, offset elements will be discarded. More...
MDLabel	orderLabel
	Label to which apply sort of the results. More...
bool	asc

Detailed Description

This is the base class for queries on MetaData. It is abstract, so it can not be instanciated. Queries will be very helpful for performing several tasks on MetaData like importing, searching or removing objects.

Definition at line 41 of file metadata_query.h.

Constructor & Destructor Documentation

MDQuery()

MDQuery::MDQuery ( int  limit = -1, int  offset = 0, MDLabel  orderLabel = MDL_OBJID, bool  asc = true  )

inline

Constructor.

Definition at line 50 of file metadata_query.h.

    {
        this->limit = limit;
        this->offset = offset;
        this->orderLabel = orderLabel;
        this->asc=asc;
    }

~MDQuery()

virtual MDQuery::~MDQuery ( )

inlinevirtual

Destructor

Definition at line 59 of file metadata_query.h.

{}

Member Function Documentation

limitString()

String MDQuery::limitString

(

)

const

Return the LIMIT string to be used in SQL

Definition at line 3 of file metadata_query.cpp.

{
    if (limit == -1 && offset > 0)
        REPORT_ERROR(ERR_MD_SQL, "Sqlite does not support OFFSET without LIMIT");
    std::stringstream ss;
    if (limit != -1)
        ss << " LIMIT " << limit << " ";
    if (offset > 0)
        ss << " OFFSET " << offset << " ";
    return ss.str();
}

orderByString()

String MDQuery::orderByString ( ) const

inline

Return the ORDER BY string to be used in SQL query

Definition at line 62 of file metadata_query.h.

    {
        return (String)" ORDER BY " + MDL::label2Str(orderLabel) + (asc ? " ASC" : " DESC");
    }

queryStringFunc()

virtual String MDQuery::queryStringFunc ( ) const

inlinevirtual

Return the query string, should be overrided in subclasses

Reimplemented in MDMultiQuery, MDExpression, MDValueRange, and MDValueRelational.

Definition at line 78 of file metadata_query.h.

    {
        return " ";
    }

whereString()

String MDQuery::whereString ( ) const

inline

Return the WHERE string to be used in SQL query

Definition at line 71 of file metadata_query.h.

    {
        String queryString = this->queryStringFunc();
        return (queryString == " ") ? " " : " WHERE " + queryString + " ";
    }

Member Data Documentation

asc

bool MDQuery::asc

Definition at line 47 of file metadata_query.h.

limit

int MDQuery::limit

If distint of -1 the results will be limited to this value.

Definition at line 44 of file metadata_query.h.

offset

int MDQuery::offset

If distint of 0, offset elements will be discarded.

Definition at line 45 of file metadata_query.h.

orderLabel

MDLabel MDQuery::orderLabel

Label to which apply sort of the results.

Definition at line 46 of file metadata_query.h.

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The documentation for this class was generated from the following files:

• xmippCore/core/metadata_query.h
• xmippCore/core/metadata_query.cpp