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  • 自己编写SqlHelper(11)

    第一步编写SqlHelper类,在项目根文件右击添加类命名为SqlHelper.cs代码如下:(步骤均在之前相同的项目中)

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Configuration;
    using System.Data.SqlClient;
    using System.Data;
    
    namespace ExecuteReader执行查询
    {
        class SqlHelper
        {
            private static string connStr = ConfigurationManager.ConnectionStrings["dbConnStr"].ConnectionString;
            //封装方法的原则是:把不变的放到方法里,变化的方法参数中
            public static int ExecuteNonQuery(string sql)
            {
                using (SqlConnection conn = new SqlConnection(connStr))
                {
                    conn.Open();
                    using (SqlCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = sql;
                        return cmd.ExecuteNonQuery();
                    }
                }
            }
            public static object ExecuteScalar(string sql)
            {
                using (SqlConnection conn = new SqlConnection(connStr))
                {
                    conn.Open();
                    using (SqlCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = sql;
                        return cmd.ExecuteScalar();
                    }
                }
            }
            public static DataSet ExecuteDataSet(string sql)
            {
    
                using (SqlConnection conn = new SqlConnection(connStr))
                {
                    conn.Open();
                    using (SqlCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = sql;
                        SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                        DataSet dataset = new DataSet();
                        adapter.Fill(dataset);
                        return dataset;
                     }
                }
            }
         public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)
            {
                using (SqlConnection conn = new SqlConnection(connStr))
                {
                    conn.Open();
                    using (SqlCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = sql;
                        cmd.Parameters.AddRange(parameters);
                        SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                        DataSet ds = new DataSet();
                        adapter.Fill(ds);
                        return ds.Tables[0];
                    }
                }
             } } }

    第二步:在窗体btnSqlHelper,并为其添加Click事件,代码如下:

    private void btnSqlHelper_Click(object sender, RoutedEventArgs e)
            {
                int change =SqlHelper.ExecuteNonQuery("insert into T_Student(Name,Age) values('三郎',18)");
                int j = (int)SqlHelper.ExecuteScalar("select count(*) from  T_Student");
                MessageBox.Show(change+","+j);

                DataTable table1 = SqlHelper.ExecuteDataTable("select * from T_Student where Name=@Name or Age>@Age", new SqlParameter("@Name", "战一"), new SqlParameter("Age", 20));
                foreach (DataRow row in table1.Rows)
                {
                    string name = (string)row["Name"];
                    MessageBox.Show(name);
                }

                DataSet dataset = SqlHelper.ExecuteDataSet("select * from  T_Student where Age>20");
                DataTable table = dataset.Tables[0];
                //DataRowCollection rows = table.Rows;
                //for (int i = 0; i < rows.Count; i++)
                //{
                //    DataRow row = rows[i];
                //    int age = (int)row["Age"];
                //    string name = (string)row["Name"];
                //    MessageBox.Show(name + "," + age);
                // }
                foreach (DataRow row in dataset.Tables[0].Rows)
                {
                    int age = (int)row["Age"];
                    MessageBox.Show(age.ToString());
                }
            }
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  • 原文地址:https://www.cnblogs.com/qiushuixizhao/p/3106690.html
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