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SqliteTableModel: Support EXPLAIN and PRAGMA queries again

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Change the approach to count the total number of rows returned by an SQL
query to also support EXPLAIN and PRAGMA statements. These failed before
because you are not allowed to put them into a COUNT query. This commit
adds the code needed to count the number of rows manually when one of
these queries is executed.
This commit is contained in:
Martin Kleusberg
2013-06-01 14:41:25 +02:00
parent 40f8a28fad
commit 13c3963651
2 changed files with 55 additions and 23 deletions
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77
src/sqlitetablemodel.cpp
View File

@@ -52,30 +52,12 @@ void SqliteTableModel::setQuery(const QString& sQuery, bool dontClearHeaders)
if(!m_db->isOpen())
return;
sqlite3_stmt *stmt;
m_rowCount = 0;
m_sQuery = rtrimChar(sQuery, ';');
m_sQuery = sQuery.trimmed();
// do a count query to get the full row count in a fast manner
QString sCountQuery = QString("SELECT COUNT(*) FROM (%1);").arg(m_sQuery);
m_db->logSQL(sCountQuery, kLogMsg_App);
QByteArray utf8Query = sCountQuery.toUtf8();
int status = sqlite3_prepare_v2(m_db->_db, utf8Query, utf8Query.size(), &stmt, NULL);
if(SQLITE_OK == status)
m_rowCount = getQueryRowCount();
if(m_rowCount == -1)
{
status = sqlite3_step(stmt);
if(SQLITE_ROW == status)
{
QString sCount = QString::fromUtf8((const char *) sqlite3_column_text(stmt, 0));
m_rowCount = sCount.toInt();
}
sqlite3_finalize(stmt);
}
else
{
qWarning() << "Count query failed: " << sCountQuery;
sqlite3_finalize(stmt);
m_valid = false;
return;
}
@@ -83,8 +65,9 @@ void SqliteTableModel::setQuery(const QString& sQuery, bool dontClearHeaders)
// headers
if(!dontClearHeaders)
{
utf8Query = sQuery.toUtf8();
status = sqlite3_prepare_v2(m_db->_db, utf8Query, utf8Query.size(), &stmt, NULL);
sqlite3_stmt* stmt;
QByteArray utf8Query = sQuery.toUtf8();
int status = sqlite3_prepare_v2(m_db->_db, utf8Query, utf8Query.size(), &stmt, NULL);
if(SQLITE_OK == status)
{
status = sqlite3_step(stmt);
@@ -103,6 +86,54 @@ void SqliteTableModel::setQuery(const QString& sQuery, bool dontClearHeaders)
emit layoutChanged();
}
int SqliteTableModel::getQueryRowCount()
{
// Return -1 if there is an error
int retval = -1;
// Use a different approach of determining the row count when a EXPLAIN or a PRAGMA statement is used because a COUNT fails on these queries
if(m_sQuery.startsWith("EXPLAIN", Qt::CaseInsensitive) || m_sQuery.startsWith("PRAGMA", Qt::CaseInsensitive))
{
// So just execute the statement as it is and fetch all results counting the rows
sqlite3_stmt* stmt;
QByteArray utf8Query = m_sQuery.toUtf8();
if(sqlite3_prepare_v2(m_db->_db, utf8Query, utf8Query.size(), &stmt, NULL) == SQLITE_OK)
{
retval = 0;
while(sqlite3_step(stmt) == SQLITE_ROW)
retval++;
sqlite3_finalize(stmt);
// Return the results but also set the chunk size the number of rows to prevent the lazy population mechanism to kick in as using LIMIT
// fails on this kind of queries as well
m_chunkSize = retval;
return retval;
}
} else {
// If it is a normal query - hopefully starting with SELECT - just do a COUNT on it and return the results
QString sCountQuery = QString("SELECT COUNT(*) FROM (%1);").arg(rtrimChar(m_sQuery, ';'));
m_db->logSQL(sCountQuery, kLogMsg_App);
QByteArray utf8Query = sCountQuery.toUtf8();
sqlite3_stmt* stmt;
int status = sqlite3_prepare_v2(m_db->_db, utf8Query, utf8Query.size(), &stmt, NULL);
if(status == SQLITE_OK)
{
status = sqlite3_step(stmt);
if(status == SQLITE_ROW)
{
QString sCount = QString::fromUtf8((const char*)sqlite3_column_text(stmt, 0));
retval = sCount.toInt();
}
sqlite3_finalize(stmt);
} else {
qWarning() << "Count query failed: " << sCountQuery;
}
}
return retval;
}
int SqliteTableModel::rowCount(const QModelIndex&) const
{
return m_data.size(); // current fetched row count

1
src/sqlitetablemodel.h
View File

@@ -49,6 +49,7 @@ private:
void clearCache();
void buildQuery();
int getQueryRowCount();
DBBrowserDB* m_db;
int m_rowCount;