C#winform学习4(tab光标顺序、子窗口打开限制、提示框、定时器、状态栏用户时间、下拉显示、查询功能)

标签：状态栏 C# void private tab new mySqlConnection ds string

1.更改光标顺序

视图-->Tab键顺序

启动的时候，光标就会在用户名的文本框中,并且在按tab键的时候，光标就会按照我们定的顺序显示。即用户名文本框--tab-->密码文本框--tab-->登录--tab-->重置

2.新建类

右键-->添加-->类

写入代码，封装字段生成属性，右键-->重构-->封装字段-->确认-->确认

3.控制有些窗口只能打开一个

代码示例：

private void 员工列表ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            //先判断当前窗口中有没有员工列表这个窗体
            //如果有则将其放到所有窗口的最前面，如果没有就打开窗体
            foreach(Form item in this.MdiChildren)
            {
                if(item.GetType().Name == "StaffForm")
                {
                    item.BringToFront();
                    return;
                }
            }
            //如果没有该窗体的情况:
            StaffForm staffForm = new StaffForm();
            staffForm.MdiParent = this;
            staffForm.Show();
        }

4.关闭窗口的时候提示信息

在对应的窗口中找到这个然后双击

        private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            DialogResult dialogResult = MessageBox.Show("确定退出系统吗? ", "系统提示", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
            if(dialogResult == DialogResult.Yes)
            {
                Application.ExitThread();
            }
            else
            {
                //取消事件
                e.Cancel = true;
            }
        }

        private void 退出系统ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            //退出系统:this.Close()会继承上面的窗体关闭操作
            //提示框与MainForm_FormClosing里面的提示框内容相同
            this.Close(); 
        }

        private void toolStripButton3_Click(object sender, EventArgs e)
        {
            //退出系统
            this.Close();
        }

5.关闭所有子窗体

        private void toolStripButton4_Click(object sender, EventArgs e)
        {
            //关闭所有子窗体
            DialogResult dialogResult = MessageBox.Show("确定要关闭所有子窗体吗? ","系统提示",MessageBoxButtons.YesNo,MessageBoxIcon.Question);
            if(dialogResult == DialogResult.Yes)
            {
                //激活状态的子窗体
                Form activeChild = this.ActiveMdiChild;
                while(activeChild != null)
                {
                    //关闭已打开的子窗体
                    activeChild.Close();
                    activeChild = this.ActiveMdiChild;
                }
            }
        }

6.定时器

添加事件

private void timer1_Tick(object sender, EventArgs e)
        {
            DateTime dateTime = DateTime.Now;
            toolStripStatusLabel3.Text = dateTime.ToString("yyyy年MM月dd日 HH:mm:ss");
        }

7.窗体加载更新当前登录用户

private void MainForm_Load(object sender, EventArgs e)
        {
            toolStripStatusLabel2.Text = User.Uname;
        }

8.员工列表显示

private void StaffForm_Load(object sender, EventArgs e)
        {
            MySqlConnection mySqlConnection = new MySqlConnection("server=127.0.0.1;port=3306;user=root;password=123456;database=course");
            mySqlConnection.Open();
            string sql = string.Format("select sId as '编号',sCard as '工号',sName as '姓名',\r\nsSex as '性别',sAge as '年龄',sAddress as '地址',\r\ndeptName as '部门',sWages as '工资'\r\nfrom staffinfo s INNER JOIN deptinfo d on s.deptId = d.deptId;");
            MySqlDataAdapter msda = new MySqlDataAdapter(sql, mySqlConnection);
            DataSet ds = new DataSet();
            msda.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0];
            mySqlConnection.Close();
        }

9.下拉框显示

private void StaffForm_Load(object sender, EventArgs e)
        {
            //初始化
            setDataGridView();
            setComboBox();
        }
       /// <summary>
       /// 初始化ComboBox
       /// </summary>
        private void setComboBox()
        {
            MySqlConnection mySqlConnection = new MySqlConnection("server=127.0.0.1;port=3306;user=root;password=123456;database=course");
            mySqlConnection.Open();
            string sql = string.Format("select deptId,deptName from deptinfo");
            MySqlDataAdapter msda = new MySqlDataAdapter(sql, mySqlConnection);
            DataSet ds = new DataSet();
            msda.Fill(ds);

            //显示值
            comboBox1.DisplayMember = "deptName";
            //隐藏值
            comboBox1.ValueMember = "deptId";

            comboBox1.DataSource = ds.Tables[0];
            mySqlConnection.Close();
        }

效果：

在下拉框默认显示请选择，需要在查询数据之后添加多一条数据

        private void StaffForm_Load(object sender, EventArgs e)
        {
            //初始化
            setDataGridView();
            setComboBox();
        }

       /// <summary>
       /// 初始化ComboBox
       /// </summary>
        private void setComboBox()
        {
            MySqlConnection mySqlConnection = new MySqlConnection("server=127.0.0.1;port=3306;user=root;password=123456;database=course");
            mySqlConnection.Open();
            string sql = string.Format("select deptId,deptName from deptinfo");
            MySqlDataAdapter msda = new MySqlDataAdapter(sql, mySqlConnection);
            DataSet ds = new DataSet();


            //msda.Fill(ds);
            msda.Fill(ds, "depts");
            //添加请选择
            DataRow dr = ds.Tables["depts"].NewRow();
            dr[0] = "0";
            dr[1] = "请选择";
            ds.Tables["depts"].Rows.InsertAt(dr, 0);


            //显示值
            comboBox1.DisplayMember = "deptName";
            //隐藏值
            comboBox1.ValueMember = "deptId";

            comboBox1.DataSource = ds.Tables["depts"];
            mySqlConnection.Close();
        }

效果:

10.员工列表添加多条件查询

private void StaffForm_Load(object sender, EventArgs e)
        {
            //初始化DataDridView列表数据
            setDataGridView();
            //初始化ComboBox下拉框
            setComboBox();
            //
        }

        /// <summary>
        /// 初始化DataGridView数据列表
        /// </summary>
        private void setDataGridView()
        {
            MySqlConnection mySqlConnection = new MySqlConnection("server=127.0.0.1;port=3306;user=root;password=123456;database=course");
            mySqlConnection.Open();
            //string sql = string.Format("select sId as '编号',sCard as '工号',sName as '姓名',\r\nsSex as '性别',sAge as '年龄',sAddress as '地址',\r\ndeptName as '部门',sWages as '工资'\r\nfrom staffinfo s INNER JOIN deptinfo d on s.deptId = d.deptId;");
            //条件查询
            string sql = string.Format("select sId as '编号',sCard as '工号',sName as '姓名',\r\nsSex as '性别',sAge as '年龄',sAddress as '地址',\r\ndeptName as '部门',sWages as '工资'\r\nfrom staffinfo s INNER JOIN deptinfo d on s.deptId = d.deptId where 1=1");
            if (textBox1.Text.Trim().Length !=0)
            {
                //注意最前面要写空格
                sql += string.Format(" and sCard like '%{0}%'", textBox1.Text.Trim());
            }
            if(textBox2.Text.Trim().Length !=0)
            {
                sql += string.Format(" and sName like '%{0}'", textBox2.Text.Trim());
            }
            if(comboBox1.SelectedIndex > 0)
            {
                sql += string.Format(" and deptName like '%{0}'", comboBox1.Text.Trim());
            }
            
            
            MySqlDataAdapter msda = new MySqlDataAdapter(sql, mySqlConnection);
            DataSet ds = new DataSet();
            msda.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0];
            mySqlConnection.Close();
        }
       /// <summary>
       /// 初始化ComboBox下拉框
       /// </summary>
        private void setComboBox()
        {
            MySqlConnection mySqlConnection = new MySqlConnection("server=127.0.0.1;port=3306;user=root;password=123456;database=course");
            mySqlConnection.Open();
            string sql = string.Format("select deptId,deptName from deptinfo");
            MySqlDataAdapter msda = new MySqlDataAdapter(sql, mySqlConnection);
            DataSet ds = new DataSet();


            //msda.Fill(ds);
            msda.Fill(ds, "depts");
            //添加请选择
            DataRow dr = ds.Tables["depts"].NewRow();
            dr[0] = "0";
            dr[1] = "请选择";
            ds.Tables["depts"].Rows.InsertAt(dr, 0);


            //显示值
            comboBox1.DisplayMember = "deptName";
            //隐藏值
            comboBox1.ValueMember = "deptId";

            comboBox1.DataSource = ds.Tables["depts"];
            mySqlConnection.Close();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            setDataGridView();
        }

标签：状态栏,C#,void,private,tab,new,mySqlConnection,ds,string
From： https://www.cnblogs.com/hmy22466/p/17822393.html