一.//连接方式访问数据库的主要步骤(利用DataReader对象实现数据库连接模式) 1.创建连接对象(连接字符串) SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["XXX"].ConnectionString); 2.创建命令对象(设置Command对象的几个属性值) SqlCommand scmd = new SqlCommand(); scmd.CommandText
private void Button_Click_1(object sender, RoutedEventArgs e) { //非链接方式访问数据库, //1创建连接对象(连接字符串) using (SqlConnection conn = new SqlConnection(SQLHelper.ConnectionString)) { //2.创建数据适配器对象 using (SqlDataAdapter sda = new SqlDataAdapter("select * from St
一.SQL子查询语句 1.单行子查询 select ename,deptno,sal from emp where deptno=(select deptno from dept where loc='NEW YORK'): 2.多行子查询 SELECT ename,job,sal FROM EMP WHERE deptno in ( SELECT deptno FROM dept WHERE dnam