ADD file via upload

src/data_base.cpp

@@ -0,0 +1,118 @@
+#include "data_base.h"
+
+QSqlDatabase database;
+void Data_base::set_database()
+{
+
+    // 创建数据库，命名为Pet_project.db
+
+        database = QSqlDatabase::addDatabase("QSQLITE");
+        database.setDatabaseName("Pet_project.db");
+        if (!database.open())
+        {
+            qDebug() << "Error: Failed to connect database." << database.lastError();
+        }
+        else
+        {
+            qDebug() << "Succeed to connect database." ;
+        }
+}
+
+void Data_base::delete_table(){
+
+            //删除表格
+    QSqlQuery to_user;
+    to_user.exec("drop table USER");
+    if(to_user.exec())
+                {
+                    qDebug() << to_user.lastError();
+                }
+    else
+                {
+                    qDebug() << "Table cleared";
+                }
+
+}
+
+void Data_base::creat_table()
+{
+    //在数据库中新建立一个表格，用于记录用户信息
+        QSqlQuery to_user;
+        QStringList table_list = database.tables();
+
+        if(!table_list.contains("USER"))
+        {
+         //在数据库中新建立一个表格，用于记录用户信息
+        if(!to_user.exec("create table USER(user_name varchar primary key,password varchar)"))
+        {
+            qDebug() << "Error: Fail to create table."<< to_user.lastError();
+        }
+        else{
+            qDebug() << "Table user created!";
+        }
+
+        }
+        else{
+            qDebug()<<"USER already exist";
+        }
+
+        QString Username = "pet";
+        QString s = QString("SELECT * FROM USER where user_name='%1' ").arg(Username);
+        to_user.exec(s);
+
+        int num=0;
+        while(to_user.next())
+        {
+            num++;
+        }
+        if(num==0)
+        {
+        //给用户表中插入一个初始的用户,我的超级用户
+        to_user.exec("insert into USER values('pet', '123456')");
+        }
+
+
+
+        if(!table_list.contains("COMMUNICATION"))
+        {
+         //在数据库中新建立一个表格，用于记录用户信息
+        if(!to_user.exec("create table COMMUNICATION(the_content varchar,the_user varchar)"))
+        {
+            qDebug() << "Error: Fail to create Communication table."<< to_user.lastError();
+        }
+        else{
+            qDebug() << "Table COMMUNICATION created!";
+        }
+
+
+        }
+
+        else{
+            qDebug()<<"COMMUNICATION already exist";
+        }
+
+
+
+}
+
+bool Data_base::check_user(QString Username, QString Password)
+{
+
+    if(database.open())
+    {
+        QSqlQuery check(database);
+        //查询是给返回一个满足条件的表，如果没有，表为空，check一开始指向的是返回的表之外
+        QString s = QString("SELECT * FROM USER where user_name='%1' and password='%2' ").arg(Username).arg(Password);
+        check.exec(s);
+
+        int num=0;
+        while(check.next())
+        {
+            num++;
+        }
+
+        if(num!=0) return true;
+        else return false;
+
+    }
+}