multi row select from SQLite
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Hi friends, i want to select at least two rows from SQL, but i can't, can you help me guys??
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Hi friends, i want to select at least two rows from SQL, but i can't, can you help me guys??
@SeyMohsenFls Please show your code. How are you trying to do this?
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@SeyMohsenFls Please show your code. How are you trying to do this?
@artwaw i can just get one number like this:
QSqlQuery q1; QString comp1= ui->lineEdit->text(); QString comp2= ui->lineEdit_2->text(); q1.exec("SELECT ["+comp2+"] From Par_A WHERE C_id='"+comp1+"'");but i want get a row of data from a table in SQL then move that to a matrix like this:
a[5]={0,5,9,7,3}; -
@artwaw i can just get one number like this:
QSqlQuery q1; QString comp1= ui->lineEdit->text(); QString comp2= ui->lineEdit_2->text(); q1.exec("SELECT ["+comp2+"] From Par_A WHERE C_id='"+comp1+"'");but i want get a row of data from a table in SQL then move that to a matrix like this:
a[5]={0,5,9,7,3};@SeyMohsenFls I think the pair of
[]is not necessary, you can just simplify query to"select "+comp2+"from Par_A where C_id="+comp1+";"- sqlite is quite relaxed. if course, if C_id is of type text'use might be necessary.
When you run your original query - what doesq1.lastQuery()return? What is the return value ofq1.lastError().text()?You can add
qDebug() << q1.lastQuery(); qDebug() << q1.lastError().text();after the exec, this should throw out results into the console.As for processing results, QSqlQuery documentation webpage tells you how to proceed (I assume you want a list of int):
QVector<int> results; while (q1.next()) { results.append(q1.value(0).toInt(); } -
@SeyMohsenFls I think the pair of
[]is not necessary, you can just simplify query to"select "+comp2+"from Par_A where C_id="+comp1+";"- sqlite is quite relaxed. if course, if C_id is of type text'use might be necessary.
When you run your original query - what doesq1.lastQuery()return? What is the return value ofq1.lastError().text()?You can add
qDebug() << q1.lastQuery(); qDebug() << q1.lastError().text();after the exec, this should throw out results into the console.As for processing results, QSqlQuery documentation webpage tells you how to proceed (I assume you want a list of int):
QVector<int> results; while (q1.next()) { results.append(q1.value(0).toInt(); }@artwaw
i got this from that qDebug:"SELECT [4] From Par_A WHERE C_id='2'" ""there is no error.
i have another question. how can i input the value of a query to a variable before check the query?
i wrote this code but it's wrong!QSqlQuery q1; q1.exec("SELECT ["+comp2+"] From Par_A WHERE C_id='"+comp1+"'"); double a=q1.value(0).toDouble(); if(q1.first() ) { //i dont want write ****a=q1.value(0).toDouble();**** here!!!!! } else { ui->text1->setText("not found!!!!!!!!"); } -
@artwaw
i got this from that qDebug:"SELECT [4] From Par_A WHERE C_id='2'" ""there is no error.
i have another question. how can i input the value of a query to a variable before check the query?
i wrote this code but it's wrong!QSqlQuery q1; q1.exec("SELECT ["+comp2+"] From Par_A WHERE C_id='"+comp1+"'"); double a=q1.value(0).toDouble(); if(q1.first() ) { //i dont want write ****a=q1.value(0).toDouble();**** here!!!!! } else { ui->text1->setText("not found!!!!!!!!"); }@SeyMohsenFls pls try to apply the query I wrote (leave the check code just in case I did something wrong). Do not forget the
;at the end.You can't,
while (query.next())is the way to go as far as I can tell. Please read the documentation. -
@SeyMohsenFls pls try to apply the query I wrote (leave the check code just in case I did something wrong). Do not forget the
;at the end.You can't,
while (query.next())is the way to go as far as I can tell. Please read the documentation.@artwaw
thank you. I read documentation and problem solved.
