qgssqlstatement.cpp

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/***************************************************************************
                              qgssqlstatement.cpp
                             -------------------
    begin                : April 2016
    copyright            : (C) 2011 by Martin Dobias
    copyright            : (C) 2016 by Even Rouault
    email                : even.rouault at spatialys.com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgssqlstatement.h"
 
#include <cmath>
#include <limits>
 
#include "qgis.h"
#include "qgsexpression.h"
#include "qgsvariantutils.h"
 
#include <QRegularExpression>
#include <QString>
 
using namespace Qt::StringLiterals;
 
// from parser
extern QgsSQLStatement::Node *parse( const QString &str, QString &parserErrorMsg, bool allowFragments );

// operators
 
const char *QgsSQLStatement::BINARY_OPERATOR_TEXT[] = {
  // this must correspond (number and order of element) to the declaration of the enum BinaryOperator
  "OR", "AND", "=", "<>", "<=", ">=", "<", ">", "LIKE", "NOT LIKE", "ILIKE", "NOT ILIKE", "IS", "IS NOT", "+", "-", "*", "/", "//", "%", "^", "||"
};
 
const char *QgsSQLStatement::UNARY_OPERATOR_TEXT[] = {
  // this must correspond (number and order of element) to the declaration of the enum UnaryOperator
  "NOT",
  "-"
};
 
const char *QgsSQLStatement::JOIN_TYPE_TEXT[] = {
  // this must correspond (number and order of element) to the declaration of the enum JoinType
  "",
  "LEFT",
  "LEFT OUTER",
  "RIGHT",
  "RIGHT OUTER",
  "CROSS",
  "INNER",
  "FULL"
};

 
QString QgsSQLStatement::statement() const
{
  if ( !mStatement.isNull() )
    return mStatement;
  else
    return dump();
}
 
QString QgsSQLStatement::dump() const
{
  if ( !mRootNode )
    return tr( "(no root)" );
 
  return mRootNode->dump();
}
 
QString QgsSQLStatement::quotedIdentifier( QString name )
{
  return u"\"%1\""_s.arg( name.replace( '\"', "\"\""_L1 ) );
}
 
QString QgsSQLStatement::quotedIdentifierIfNeeded( const QString &name )
{
  // This might not be complete, but it must be at least what we recognize
  static const char *const RESERVED_KEYWORDS[] = { "AND",   "OR",    "NOT",   "LIKE", "IN",      "IS",    "BETWEEN", "NULL",  "SELECT", "ALL",   "DISTINCT", "CAST",
                                                   "AS",    "FROM",  "JOIN",  "ON",   "USING",   "WHERE", "ORDER",   "BY",    "ASC",    "DESC",  "LEFT",     "RIGHT",
                                                   "INNER", "OUTER", "CROSS", "FULL", "NATURAL", "UNION", "OFFSET",  "LIMIT", "GROUP",  "HAVING" };
 
  for ( size_t i = 0; i < sizeof( RESERVED_KEYWORDS ) / sizeof( RESERVED_KEYWORDS[0] ); ++i )
  {
    if ( name.compare( QString( RESERVED_KEYWORDS[i] ), Qt::CaseInsensitive ) == 0 )
    {
      return quotedIdentifier( name );
    }
  }
  const thread_local QRegularExpression IDENTIFIER_RE( "^[A-Za-z_\\x80-\\xff][A-Za-z0-9_\\x80-\\xff]*$" );
  return IDENTIFIER_RE.match( name ).hasMatch() ? name : quotedIdentifier( name );
}
 
QString QgsSQLStatement::stripQuotedIdentifier( QString text )
{
  if ( text.length() >= 2 && text[0] == '"' && text[text.length() - 1] == '"' )
  {
    // strip double quotes on start,end
    text = text.mid( 1, text.length() - 2 );
 
    // make single "double quotes" from double "double quotes"
    text.replace( "\"\""_L1, "\""_L1 );
  }
  return text;
}
 
QString QgsSQLStatement::stripMsQuotedIdentifier( QString text )
{
  if ( text.length() >= 2 && text[0] == '[' && text[text.length() - 1] == ']' )
  {
    // strip square brackets on start,end
    text = text.mid( 1, text.length() - 2 );
  }
  return text;
}
 
QString QgsSQLStatement::quotedString( QString text )
{
  text.replace( '\'', "''"_L1 );
  text.replace( '\\', "\\\\"_L1 );
  text.replace( '\n', "\\n"_L1 );
  text.replace( '\t', "\\t"_L1 );
  return u"'%1'"_s.arg( text );
}
 
QgsSQLStatement::QgsSQLStatement( const QString &expr )
  : QgsSQLStatement( expr, false )
{}
 
QgsSQLStatement::QgsSQLStatement( const QString &expr, bool allowFragments )
  : mAllowFragments( allowFragments )
{
  mRootNode.reset( ::parse( expr, mParserErrorString, mAllowFragments ) );
  mStatement = expr;
}
 
QgsSQLStatement::QgsSQLStatement( const QgsSQLStatement &other )
  : mAllowFragments( other.mAllowFragments )
  , mStatement( other.mStatement )
{
  mRootNode.reset( ::parse( mStatement, mParserErrorString, mAllowFragments ) );
}
 
QgsSQLStatement &QgsSQLStatement::operator=( const QgsSQLStatement &other )
{
  if ( &other != this )
  {
    mParserErrorString.clear();
    mStatement = other.mStatement;
    mAllowFragments = other.mAllowFragments;
    mRootNode.reset( ::parse( mStatement, mParserErrorString, mAllowFragments ) );
  }
  return *this;
}
 
QgsSQLStatement::~QgsSQLStatement()
{}
 
bool QgsSQLStatement::hasParserError() const
{
  return !mParserErrorString.isNull() || ( !mRootNode && !mAllowFragments );
}
 
QString QgsSQLStatement::parserErrorString() const
{
  return mParserErrorString;
}
 
void QgsSQLStatement::acceptVisitor( QgsSQLStatement::Visitor &v ) const
{
  if ( mRootNode )
    mRootNode->accept( v );
}
 
const QgsSQLStatement::Node *QgsSQLStatement::rootNode() const
{
  return mRootNode.get();
}
 
void QgsSQLStatement::RecursiveVisitor::visit( const QgsSQLStatement::NodeSelect &n )
{
  const auto constTables = n.tables();
  for ( QgsSQLStatement::NodeTableDef *table : constTables )
  {
    table->accept( *this );
  }
  const auto constColumns = n.columns();
  for ( QgsSQLStatement::NodeSelectedColumn *column : constColumns )
  {
    column->accept( *this );
  }
  const auto constJoins = n.joins();
  for ( QgsSQLStatement::NodeJoin *join : constJoins )
  {
    join->accept( *this );
  }
  QgsSQLStatement::Node *where = n.where();
  if ( where )
    where->accept( *this );
  const auto constOrderBy = n.orderBy();
  for ( QgsSQLStatement::NodeColumnSorted *column : constOrderBy )
  {
    column->accept( *this );
  }
}
 
void QgsSQLStatement::RecursiveVisitor::visit( const QgsSQLStatement::NodeJoin &n )
{
  n.tableDef()->accept( *this );
  QgsSQLStatement::Node *expr = n.onExpr();
  if ( expr )
    expr->accept( *this );
}

class QgsSQLStatementCollectTableNames : public QgsSQLStatement::RecursiveVisitor
{
  public:
    typedef QPair<QString, QString> TableColumnPair;

    QgsSQLStatementCollectTableNames() = default;
 
    using QgsSQLStatement::RecursiveVisitor::visit;
    void visit( const QgsSQLStatement::NodeColumnRef &n ) override;
    void visit( const QgsSQLStatement::NodeTableDef &n ) override;
 
    QSet<QString> tableNamesDeclared;
    QSet<TableColumnPair> tableNamesReferenced;
};
 
void QgsSQLStatementCollectTableNames::visit( const QgsSQLStatement::NodeColumnRef &n )
{
  if ( !n.tableName().isEmpty() )
    tableNamesReferenced.insert( TableColumnPair( n.tableName(), n.name() ) );
  QgsSQLStatement::RecursiveVisitor::visit( n );
}
 
void QgsSQLStatementCollectTableNames::visit( const QgsSQLStatement::NodeTableDef &n )
{
  tableNamesDeclared.insert( n.alias().isEmpty() ? ( n.schema().isEmpty() ? n.name() : n.schema() + '.' + n.name() ) : n.alias() );
  QgsSQLStatement::RecursiveVisitor::visit( n );
}
 
bool QgsSQLStatement::doBasicValidationChecks( QString &errorMsgOut ) const
{
  errorMsgOut.clear();
  if ( !mRootNode )
  {
    errorMsgOut = tr( "No root node" );
    return false;
  }
  QgsSQLStatementCollectTableNames v;
  mRootNode->accept( v );
 
  for ( const QgsSQLStatementCollectTableNames::TableColumnPair &pair : std::as_const( v.tableNamesReferenced ) )
  {
    if ( !v.tableNamesDeclared.contains( pair.first ) )
    {
      if ( !errorMsgOut.isEmpty() )
        errorMsgOut += ' '_L1;
      errorMsgOut += tr( "Table %1 is referenced by column %2, but not selected in FROM / JOIN." ).arg( pair.first, pair.second );
    }
  }
 
  return errorMsgOut.isEmpty();
}

// nodes
 
void QgsSQLStatement::NodeList::accept( QgsSQLStatement::Visitor &v ) const
{
  for ( QgsSQLStatement::Node *node : mList )
  {
    node->accept( v );
  }
}
 
QgsSQLStatement::NodeList *QgsSQLStatement::NodeList::clone() const
{
  NodeList *nl = new NodeList;
  const auto constMList = mList;
  for ( Node *node : constMList )
  {
    nl->mList.append( node->clone() );
  }
 
  return nl;
}
 
QString QgsSQLStatement::NodeList::dump() const
{
  QString msg;
  bool first = true;
  const auto constMList = mList;
  for ( Node *n : constMList )
  {
    if ( !first )
      msg += ", "_L1;
    else
      first = false;
    msg += n->dump();
  }
  return msg;
}
 
 
//
 
QString QgsSQLStatement::NodeUnaryOperator::dump() const
{
  return u"%1 %2"_s.arg( UNARY_OPERATOR_TEXT[mOp], mOperand->dump() );
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeUnaryOperator::clone() const
{
  return new NodeUnaryOperator( mOp, mOperand->clone() );
}
 
QString QgsSQLStatement::NodeUnaryOperator::text() const
{
  return UNARY_OPERATOR_TEXT[mOp];
}
 
//
 
int QgsSQLStatement::NodeBinaryOperator::precedence() const
{
  // see left/right in qgsexpressionparser.yy
  switch ( mOp )
  {
    case boOr:
      return 1;
 
    case boAnd:
      return 2;
 
    case boEQ:
    case boNE:
    case boLE:
    case boGE:
    case boLT:
    case boGT:
    case boLike:
    case boILike:
    case boNotLike:
    case boNotILike:
    case boIs:
    case boIsNot:
      return 3;
 
    case boPlus:
    case boMinus:
      return 4;
 
    case boMul:
    case boDiv:
    case boIntDiv:
    case boMod:
      return 5;
 
    case boPow:
      return 6;
 
    case boConcat:
      return 7;
  }
  Q_ASSERT( false && "unexpected binary operator" );
  return -1;
}
 
bool QgsSQLStatement::NodeBinaryOperator::leftAssociative() const
{
  // see left/right in qgsexpressionparser.yy
  switch ( mOp )
  {
    case boOr:
    case boAnd:
    case boEQ:
    case boNE:
    case boLE:
    case boGE:
    case boLT:
    case boGT:
    case boLike:
    case boILike:
    case boNotLike:
    case boNotILike:
    case boIs:
    case boIsNot:
    case boPlus:
    case boMinus:
    case boMul:
    case boDiv:
    case boIntDiv:
    case boMod:
    case boConcat:
      return true;
 
    case boPow:
      return false;
  }
  Q_ASSERT( false && "unexpected binary operator" );
  return false;
}
 
QString QgsSQLStatement::NodeBinaryOperator::text() const
{
  return BINARY_OPERATOR_TEXT[mOp];
}
 
QString QgsSQLStatement::NodeBinaryOperator::dump() const
{
  QgsSQLStatement::NodeBinaryOperator *lOp = dynamic_cast<QgsSQLStatement::NodeBinaryOperator *>( mOpLeft.get() );
  QgsSQLStatement::NodeBinaryOperator *rOp = dynamic_cast<QgsSQLStatement::NodeBinaryOperator *>( mOpRight.get() );
  QgsSQLStatement::NodeUnaryOperator *ruOp = dynamic_cast<QgsSQLStatement::NodeUnaryOperator *>( mOpRight.get() );
 
  QString rdump( mOpRight->dump() );
 
  // avoid dumping "IS (NOT ...)" as "IS NOT ..."
  if ( mOp == boIs && ruOp && ruOp->op() == uoNot )
  {
    rdump.prepend( '(' ).append( ')' );
  }
 
  QString fmt;
  if ( leftAssociative() )
  {
    fmt += lOp && ( lOp->precedence() < precedence() ) ? "(%1)" : "%1";
    fmt += " %2 "_L1;
    fmt += rOp && ( rOp->precedence() <= precedence() ) ? "(%3)" : "%3";
  }
  else
  {
    fmt += lOp && ( lOp->precedence() <= precedence() ) ? "(%1)" : "%1";
    fmt += " %2 "_L1;
    fmt += rOp && ( rOp->precedence() < precedence() ) ? "(%3)" : "%3";
  }
 
  return fmt.arg( mOpLeft->dump(), BINARY_OPERATOR_TEXT[mOp], rdump );
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeBinaryOperator::clone() const
{
  return new NodeBinaryOperator( mOp, mOpLeft->clone(), mOpRight->clone() );
}
 
//
 
QString QgsSQLStatement::NodeInOperator::dump() const
{
  return u"%1 %2IN (%3)"_s.arg( mNode->dump(), mNotIn ? "NOT " : "", mList->dump() );
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeInOperator::clone() const
{
  return new NodeInOperator( mNode->clone(), mList->clone(), mNotIn );
}
 
//
 
QString QgsSQLStatement::NodeBetweenOperator::dump() const
{
  return u"%1 %2BETWEEN %3 AND %4"_s.arg( mNode->dump(), mNotBetween ? "NOT " : "", mMinVal->dump(), mMaxVal->dump() );
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeBetweenOperator::clone() const
{
  return new NodeBetweenOperator( mNode->clone(), mMinVal->clone(), mMaxVal->clone(), mNotBetween );
}
 
//
 
QString QgsSQLStatement::NodeFunction::dump() const
{
  return u"%1(%2)"_s.arg( mName, mArgs ? mArgs->dump() : QString() ); // function
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeFunction::clone() const
{
  return new NodeFunction( mName, mArgs ? mArgs->clone() : nullptr );
}
 
//
 
QString QgsSQLStatement::NodeLiteral::dump() const
{
  if ( QgsVariantUtils::isNull( mValue ) )
    return u"NULL"_s;
 
  switch ( mValue.userType() )
  {
    case QMetaType::Type::Int:
      return QString::number( mValue.toInt() );
    case QMetaType::Type::LongLong:
      return QString::number( mValue.toLongLong() );
    case QMetaType::Type::Double:
      return QString::number( mValue.toDouble() );
    case QMetaType::Type::QString:
      return quotedString( mValue.toString() );
    case QMetaType::Type::Bool:
      return mValue.toBool() ? "TRUE" : "FALSE";
    default:
      return tr( "[unsupported type: %1; value: %2]" ).arg( mValue.typeName(), mValue.toString() );
  }
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeLiteral::clone() const
{
  return new NodeLiteral( mValue );
}
 
QString QgsSQLStatement::NodeLiteral::valueAsString() const
{
  if ( QgsVariantUtils::isNull( mValue ) )
    return u"NULL"_s;
 
  switch ( mValue.userType() )
  {
    case QMetaType::Type::Int:
      return QString::number( mValue.toInt() );
    case QMetaType::Type::Double:
      return qgsDoubleToString( mValue.toDouble() );
    case QMetaType::Type::LongLong:
      return QString::number( mValue.toLongLong() );
    case QMetaType::Type::QString:
      return QgsExpression::quotedString( mValue.toString() );
    case QMetaType::Type::QTime:
      return QgsExpression::quotedString( mValue.toTime().toString( Qt::ISODate ) );
    case QMetaType::Type::QDate:
      return QgsExpression::quotedString( mValue.toDate().toString( Qt::ISODate ) );
    case QMetaType::Type::QDateTime:
      return QgsExpression::quotedString( mValue.toDateTime().toString( Qt::ISODate ) );
    case QMetaType::Type::Bool:
      return mValue.toBool() ? u"TRUE"_s : u"FALSE"_s;
    default:
      return tr( "[unsupported type: %1; value: %2]" ).arg( mValue.typeName(), mValue.toString() );
  }
}
 
//
 
QString QgsSQLStatement::NodeColumnRef::dump() const
{
  QString ret;
  if ( mDistinct )
    ret += "DISTINCT "_L1;
  if ( !mTableName.isEmpty() )
  {
    ret += quotedIdentifierIfNeeded( mTableName );
    ret += '.';
  }
  ret += ( mStar ) ? mName : quotedIdentifierIfNeeded( mName );
  return ret;
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeColumnRef::clone() const
{
  return cloneThis();
}
 
QgsSQLStatement::NodeColumnRef *QgsSQLStatement::NodeColumnRef::cloneThis() const
{
  NodeColumnRef *newColumnRef = new NodeColumnRef( mTableName, mName, mStar );
  newColumnRef->setDistinct( mDistinct );
  return newColumnRef;
}
 
//
 
QString QgsSQLStatement::NodeSelectedColumn::dump() const
{
  QString ret;
  ret += mColumnNode->dump();
  if ( !mAlias.isEmpty() )
  {
    ret += " AS "_L1;
    ret += quotedIdentifierIfNeeded( mAlias );
  }
  return ret;
}
 
QgsSQLStatement::NodeSelectedColumn *QgsSQLStatement::NodeSelectedColumn::cloneThis() const
{
  NodeSelectedColumn *newObj = new NodeSelectedColumn( mColumnNode->clone() );
  newObj->setAlias( mAlias );
  return newObj;
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeSelectedColumn::clone() const
{
  return cloneThis();
}
//
 
QString QgsSQLStatement::NodeTableDef::dump() const
{
  QString ret;
  if ( !mSchema.isEmpty() )
    ret += mSchema + '.';
 
  ret += quotedIdentifierIfNeeded( mName );
  if ( !mAlias.isEmpty() )
  {
    ret += " AS "_L1;
    ret += quotedIdentifierIfNeeded( mAlias );
  }
  return ret;
}
 
QgsSQLStatement::NodeTableDef *QgsSQLStatement::NodeTableDef::cloneThis() const
{
  return new NodeTableDef( mSchema, mName, mAlias );
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeTableDef::clone() const
{
  return cloneThis();
}
 
//
 
QgsSQLStatement::NodeSelect::~NodeSelect()
{
  qDeleteAll( mTableList );
  qDeleteAll( mColumns );
  qDeleteAll( mJoins );
  qDeleteAll( mOrderBy );
}
 
QString QgsSQLStatement::NodeSelect::dump() const
{
  QString ret = u"SELECT "_s;
  if ( mDistinct )
    ret += "DISTINCT "_L1;
  bool bFirstColumn = true;
  const auto constMColumns = mColumns;
  for ( QgsSQLStatement::NodeSelectedColumn *column : constMColumns )
  {
    if ( !bFirstColumn )
      ret += ", "_L1;
    bFirstColumn = false;
    ret += column->dump();
  }
  ret += " FROM "_L1;
  bool bFirstTable = true;
  const auto constMTableList = mTableList;
  for ( QgsSQLStatement::NodeTableDef *table : constMTableList )
  {
    if ( !bFirstTable )
      ret += ", "_L1;
    bFirstTable = false;
    ret += table->dump();
  }
  const auto constMJoins = mJoins;
  for ( QgsSQLStatement::NodeJoin *join : constMJoins )
  {
    ret += ' ';
    ret += join->dump();
  }
  if ( mWhere )
  {
    ret += " WHERE "_L1;
    ret += mWhere->dump();
  }
  if ( !mOrderBy.isEmpty() )
  {
    ret += " ORDER BY "_L1;
    bool bFirst = true;
    const auto constMOrderBy = mOrderBy;
    for ( QgsSQLStatement::NodeColumnSorted *orderBy : constMOrderBy )
    {
      if ( !bFirst )
        ret += ", "_L1;
      bFirst = false;
      ret += orderBy->dump();
    }
  }
  return ret;
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeSelect::clone() const
{
  QList<QgsSQLStatement::NodeSelectedColumn *> newColumnList;
  const auto constMColumns = mColumns;
  for ( QgsSQLStatement::NodeSelectedColumn *column : constMColumns )
  {
    newColumnList.push_back( column->cloneThis() );
  }
  QList<QgsSQLStatement::NodeTableDef *> newTableList;
  const auto constMTableList = mTableList;
  for ( QgsSQLStatement::NodeTableDef *table : constMTableList )
  {
    newTableList.push_back( table->cloneThis() );
  }
  QgsSQLStatement::NodeSelect *newSelect = new NodeSelect( newTableList, newColumnList, mDistinct );
  const auto constMJoins = mJoins;
  for ( QgsSQLStatement::NodeJoin *join : constMJoins )
  {
    newSelect->appendJoin( join->cloneThis() );
  }
  if ( mWhere )
  {
    newSelect->setWhere( mWhere->clone() );
  }
  QList<QgsSQLStatement::NodeColumnSorted *> newOrderByList;
  const auto constMOrderBy = mOrderBy;
  for ( QgsSQLStatement::NodeColumnSorted *columnSorted : constMOrderBy )
  {
    newOrderByList.push_back( columnSorted->cloneThis() );
  }
  newSelect->setOrderBy( newOrderByList );
  return newSelect;
}
 
//
 
QString QgsSQLStatement::NodeJoin::dump() const
{
  QString ret;
  if ( mType != jtDefault )
  {
    ret += JOIN_TYPE_TEXT[mType];
    ret += ' '_L1;
  }
  ret += "JOIN "_L1;
  ret += mTableDef->dump();
  if ( mOnExpr )
  {
    ret += " ON "_L1;
    ret += mOnExpr->dump();
  }
  else
  {
    ret += " USING ("_L1;
    bool first = true;
    const auto constMUsingColumns = mUsingColumns;
    for ( QString column : constMUsingColumns )
    {
      if ( !first )
        ret += ", "_L1;
      first = false;
      ret += quotedIdentifierIfNeeded( column );
    }
    ret += ')'_L1;
  }
  return ret;
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeJoin::clone() const
{
  return cloneThis();
}
 
QgsSQLStatement::NodeJoin *QgsSQLStatement::NodeJoin::cloneThis() const
{
  if ( mOnExpr )
    return new NodeJoin( mTableDef->cloneThis(), mOnExpr->clone(), mType );
  else
    return new NodeJoin( mTableDef->cloneThis(), mUsingColumns, mType );
}
 
//
 
QString QgsSQLStatement::NodeColumnSorted::dump() const
{
  QString ret;
  ret = mColumn->dump();
  if ( !mAsc )
    ret += " DESC"_L1;
  return ret;
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeColumnSorted::clone() const
{
  return cloneThis();
}
 
QgsSQLStatement::NodeColumnSorted *QgsSQLStatement::NodeColumnSorted::cloneThis() const
{
  return new NodeColumnSorted( mColumn->cloneThis(), mAsc );
}
 
//
 
QString QgsSQLStatement::NodeCast::dump() const
{
  QString ret( u"CAST("_s );
  ret += mNode->dump();
  ret += " AS "_L1;
  ret += mType;
  ret += ')';
  return ret;
}
 
QgsSQLStatement::Node *QgsSQLStatement::NodeCast::clone() const
{
  return new NodeCast( mNode->clone(), mType );
}
 
//
// QgsSQLStatementFragment
//
 
QgsSQLStatementFragment::QgsSQLStatementFragment( const QString &fragment )
  : QgsSQLStatement( fragment, true )
{}