[TOC] ## 概述 ## 初始化 初始化時可先傳入 QSqlDatabase; ``` QSqlQuery query(db); ``` 初始化不存在 QsqlDatabase,則使用默認得數據庫鏈接 ``` QSqlQuery query ``` ## 報錯處理 使用 QSqlQuery.lastError 查看最后得錯誤 使用 QSqlQuery.lastQuery 查看最后得執行語句 ``` if(!query.exec("select * from hs_user")){ qDebug()<<"執行失敗"<<query.lastError() <<query.lastQuery(); } ``` ## select 1. 通過索引獲取值 ``` QSqlQuery query("SELECT country FROM artist"); while (query.next()) { QString country = query.value(0).toString(); doSomething(country); } ``` 2. 通過字段先獲取索引 ``` QSqlQuery query("SELECT * FROM artist"); int fieldNo = query.record().indexOf("country"); while (query.next()) { QString country = query.value(fieldNo).toString(); doSomething(country); } ``` ## 使用預處理 prepare 1. 使用名稱占位 ``` QSqlQuery query; query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (:id, :forename, :surname)"); query.bindValue(":id", 1001); query.bindValue(":forename", "Bart"); query.bindValue(":surname", "Simpson"); query.exec(); ``` 2. 使用索引占位 ``` QSqlQuery query; query.prepare("INSERT INTO person (id, forename, surname) " "VALUES (:id, :forename, :surname)"); query.bindValue(0, 1001); query.bindValue(1, "Bart"); query.bindValue(2, "Simpson"); query.exec(); ``` ## 檢查是否有數據 first ``` if(!query.first()){ qDebug()<<"not found"; } ```