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Allow editing fields in existing DB tables

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Make it possible to rename columns and change their types even when
editing an existing table. This requires a workaround to not use the
ALTER TABLE command which is not fully supported by SQLite.
This commit is contained in:
Martin Kleusberg
2013-01-07 23:33:52 +01:00
parent b0af89c1cb
commit fac589c3e3
4 changed files with 88 additions and 16 deletions
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80
src/sqlitedb.cpp
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@@ -420,11 +420,85 @@ bool DBBrowserDB::createColumn( QString tablename, QString fieldname, QString fi
return executeSQL(sql);
}
bool DBBrowserDB::renameColumn(QString tablename, QString from, QString to, QString type) {
qDebug("rename column");
// TODO change column name and type. SQLite doesn't support natively...
bool DBBrowserDB::renameColumn(QString tablename, QString from, QString to, QString type)
{
// NOTE: This function is working around the incomplete ALTER TABLE command in SQLite. If SQLite should fully support this command one day, this entire
// function can be changed to executing something like this:
//QString sql = QString("ALTER TABLE `%1` MODIFY `%2` %3").arg(tablename).arg(to).arg(type);
//return executeSQL(sql);
// Collect information on the current DB layout
DBBrowserObject table = getObjectByName(tablename);
if(table.getname() == "" || table.getField(from).getname() == "")
{
lastErrorMessage = QString("renameColumn: cannot find table %1 with column %2").arg(tablename).arg(from);
qDebug(lastErrorMessage.toStdString().c_str());
return false;
}
// Create savepoint to be able to go back to it in case of any error
if(!executeSQL("SAVEPOINT sqlitebrowser_rename_column"))
{
lastErrorMessage = "renameColumn: creating savepoint failed";
qDebug(lastErrorMessage.toStdString().c_str());
return false;
}
// Create a new table with a name that hopefully doesn't exist yet. Its layout is exactly the same as the one of the table to change - except for the column to change
// of course
QString sql = QString("CREATE TABLE sqlitebrowser_rename_column_new_table (");
for(int i=0;i<table.fldmap.count();i++)
{
// Is this the column to rename?
if(table.fldmap.value(i).getname() == from)
sql.append(QString("`%1` %2,").arg(to).arg(type));
else
sql.append(QString("`%1` %2,").arg(table.fldmap.value(i).getname()).arg(table.fldmap.value(i).gettype()));
}
sql.remove(sql.count() - 1, 1); // Remove last comma
sql.append(");");
if(!executeSQL(sql))
{
lastErrorMessage = QString("renameColumn: creating new table failed. DB says: %1").arg(lastErrorMessage);
qDebug(lastErrorMessage.toStdString().c_str());
executeSQL("ROLLBACK TO SAVEPOINT sqlitebrowser_rename_column;");
return false;
}
// Copy the data from the old table to the new one
if(!executeSQL(QString("INSERT INTO sqlitebrowser_rename_column_new_table SELECT * FROM `%1`;").arg(tablename)))
{
lastErrorMessage = QString("renameColumn: copying data to new table failed. DB says: %1").arg(lastErrorMessage);
qDebug(lastErrorMessage.toStdString().c_str());
executeSQL("ROLLBACK TO SAVEPOINT sqlitebrowser_rename_column;");
return false;
}
// Delete the old table
if(!executeSQL(QString("DROP TABLE `%1`;").arg(tablename)))
{
lastErrorMessage = QString("renameColumn: deleting old table failed. DB says: %1").arg(lastErrorMessage);
qDebug(lastErrorMessage.toStdString().c_str());
executeSQL("ROLLBACK TO SAVEPOINT sqlitebrowser_rename_column;");
return false;
}
// Rename the temporary table
if(!renameTable("sqlitebrowser_rename_column_new_table", tablename))
{
executeSQL("ROLLBACK TO SAVEPOINT sqlitebrowser_rename_column;");
return false;
}
// Release the savepoint - everything went fine
if(!executeSQL("RELEASE SAVEPOINT sqlitebrowser_rename_column;"))
{
lastErrorMessage = QString("renameColumn: releasing savepoint failed. DB says: %1").arg(lastErrorMessage);
qDebug(lastErrorMessage.toStdString().c_str());
return false;
}
// Success
return true;
}