我正在写一个通讯录应用程序。联系人存储在 qsqlite 数据库中，并使用 QSqlQueryModel 显示。
QueryModel 默认运行一个显示所有联系人的查询。可以编辑和删除联系人。
当用户在搜索字段中输入姓名时，SearchQuery 将运行，并且仅显示与搜索词匹配的联系人。问题是我无法编辑或删除这些联系人。我收到一条错误消息，指出数据库已锁定，无法获取行。
我不明白为什么会这样。如果我可以编辑/删除默认查询的结果，那么我应该能够编辑/删除搜索查询的结果。
下面是代码：
构造函数
搜索联系人
删除联系人
构造函数（相关部分）
OpenDatabase();
DefaultModelQuery.append("SELECT Id,FirstName||' '||LastName AS FullName,");
DefaultModelQuery.append("FirstName,LastName,Email,HomeNumber,WorkNumber,MobileNumber,Address,City,Country,Birthdate FROM Contacts ");
DefaultModelQuery.append("ORDER BY FirstName;");
QSqlQuery Query(DefaultModelQuery);
ActiveQuery = Query;
Model = new QSqlQueryModel(this);
Model->setQuery(ActiveQuery);
ui->listView->setModel(Model);
ui->listView->setModelColumn(1);
搜索联系人
void Contacts::SearchContact()
{
/*1. Read Search Term
2. Decide Type
3. Generate Query
4. Execute Query.
5. If No results, return
6. If resutls, update Model, show first result.
*/
//STEP 1: Read Search Term.
QString SearchTerm = ui->SearchLineEdit->text();
if(SearchTerm.isEmpty())
return;
/*STEP 2. Decide Type
Type n : Name
Type e : Email
Type p : Number
*/
char QueryType;
if(SearchTerm.contains(QRegExp("[A-za-z-]+")))
{
if(SearchTerm.contains("@"))
QueryType = 'e';
else
QueryType = 'n';
}else if(SearchTerm.contains(QRegExp("[0-9]+")))
QueryType = 'p';
else
QueryType = 'n';
//STEP 3: Generate Query
QSqlQuery SearchQuery;
switch(QueryType)
{
case 'n':
{
QStringList Names = SearchTerm.split(" ");
if(Names.size()>=2)
{
qDebug()<<QString("Searching for %1 %2").arg(Names.first(),Names.last());
SearchQuery.prepare("SELECT Id,FirstName||' '||LastName AS FullName,FirstName,LastName,Email,HomeNumber,MobileNumber,WorkNumber,Address,City,Country,Birthdate FROM CONTACTS WHERE FirstName=:f AND LastName=:l ORDER BY FirstName");
SearchQuery.bindValue(":f",Names.first());
SearchQuery.bindValue(":l",Names.last());
}else
{
qDebug()<<QString("Searching for %1").arg(Names.first());
SearchQuery.prepare("SELECT Id,FirstName||' '||LastName AS FullName,FirstName,LastName,Email,HomeNumber,MobileNumber,WorkNumber,Address,City,Country,Birthdate FROM CONTACTS WHERE FirstName=:f OR LastName=:l ORDER BY FirstName");
SearchQuery.bindValue(":f",Names.first());
SearchQuery.bindValue(":l",Names.first());
}
break;
}
case 'e':
{
QString Email = SearchTerm.trimmed();
SearchQuery.prepare("SELECT Id,FirstName||' '||LastName AS FullName,FirstName,LastName,Email,HomeNumber,MobileNumber,WorkNumber,Address,City,Country,Birthdate FROM CONTACTS WHERE Email=:e ORDER BY FirstName");
SearchQuery.bindValue(":e",Email);
break;
}
case 'p':
{
QString Number = SearchTerm.trimmed();
SearchQuery.prepare("SELECT Id,FirstName||' '||LastName AS FullName,FirstName,LastName,Email,HomeNumber,MobileNumber,WorkNumber,Address,City,Country,Birthdate FROM CONTACTS WHERE HomeNumber=:h OR WorkNumber=:w OR MobileNumber=:m ORDER BY FirstName");
SearchQuery.bindValue(":h",Number);
SearchQuery.bindValue(":m",Number);
SearchQuery.bindValue(":w",Number);
break;
}
}
//STEP 4: Execute Query
if(!SearchQuery.exec())
{
qDebug()<<QueryType<<": "<<SearchQuery.lastError().text();
QMessageBox::information(this,
tr("Search Error"),
tr("The following error occured while trying to search contacts:\nError: %1").arg(SearchQuery.lastError().text()));
return;
}
//STEP 5: If no results, return;
/*Note:
I used the QSqlQuery::first() method here to check if there are any result or not.
I doubt this is efficient, because the function probably invovles unnecessary steps & resources.
So the following code could be made more efficient.
I can't use QSqlQuery::size() because it always returns -1.
*/
if(!SearchQuery.first())
{
QMessageBox::information(this,
tr("No Results Found"),
tr("No results were found for \"%1\"").arg(SearchTerm));
return;
}
//STEP 6: If results, update model, show first result.
Model->setQuery(SearchQuery);
QModelIndex index = Model->index(0,1);
DisplayContact(index);
ui->listView->scrollTo(index);
SetView(Contacts::View_DisplaySearchResultsView);
}
删除联系人
void Contacts::RemoveContact()
{
if(SelectedRecordId!=-1)
{
if(QMessageBox::information(this,
"Confirm Removal",
"Are you sure you want to remove this contact from your list?",
QMessageBox::Yes|QMessageBox::No)==QMessageBox::No)
return;
QSqlQuery DeleteQuery;
DeleteQuery.prepare("DELETE FROM Contacts WHERE Id = :i;");
DeleteQuery.bindValue(":i",SelectedRecordId);
if(!DeleteQuery.exec())
{
qDebug()<<DeleteQuery.lastError().text();
QMessageBox::warning(this,
tr("Error Removing Contact"),
tr("An error occured while trying to remove this contact."));
}else
{
SelectedRecordId =-1;
clear();
SetView(Contacts::View_AddContactView);
Model->setQuery(ActiveQuery);
UpdateContactCount();
}
}else
QMessageBox::warning(this,
tr("No Record Selected"),
tr("Unexpected Error: Remove Contact Operation is being attempted while no contact is selected."));
}
我真的很感激这方面的任何帮助。谢谢 ：）