通过拼接SQL字符串实现多条件查询⼀、通过拼接SQL字符串的⽅法的好处是：
1、⽅便查询条件的扩展。
2、简化业务逻辑的判断。
⼆、例⼦：
1、界⾯设计
2、点击查询的代码
///<summary>
///按条件查询
///</summary>
///<param name="sender"></param>
///<param name="e"></param>
private void BtSearch_Click_1(object sender, EventArgs e)
{
List<string> wherelist = new List<string>();
List<SqlParameter> parametlist = new List<SqlParameter>();
if (CbMzh.Checked)
{
wherelist.Add("mzh=@mzh");
parametlist.Add(new SqlParameter("@mzh", TbMzh.Text));
}
if (CbXm.Checked)
{
wherelist.Add("xm like '%'+@xm+'%'");
parametlist.Add(new SqlParameter("@xm", TbXm.Text));
}
if (CbJbmc.Checked)
{
wherelist.Add("jbzd like '%'+@jbzd+'%'");
parametlist.Add(new SqlParameter("@jbzd", TbJbmc.Text));
}
if (CbJzlb.Checked)
{
wherelist.Add("jzlb=@jzlb");
parametlist.Add(new SqlParameter("@jzlb", ComBoxJzlb.Text));
}
if (CbJzks.Checked)
{
wherelist.Add("jzks=@jzks");
parametlist.Add(new SqlParameter("@jzks", TbJzks.Text));
}
if (CbJzys.Checked)
{
wherelist.Add("jzys=@jzys");
parametlist.Add(new SqlParameter("@jzys", TbJzys.Text));
}
if (CbJzrq.Checked)
{
wherelist.Add("jzrq between @start and @end");
string start = DpStart.Value.ToString("yyyy-MM-dd") + " 00:00:00";
string end = DpEnd.Value.ToString("yyyy-MM-dd") + " 23:59:59";
parametlist.Add(new SqlParameter("@start", start));
parametlist.Add(new SqlParameter("@end", end));
}
if (CbJbmcjqcx.Checked)
{
wherelist.Add("jbzd = @jbzd");
parametlist.Add(new SqlParameter("@jbzd", TbJbmc1.Text));
}
string whereSql = string.Join(" and ", wherelist);
string sql = "select mzh,xm,xb,csny,age,pcid,jzks,jzys,jbzd,zddm,gzdw,jtzz,lxfs,jzlb,jzrq,xy from his_mzjzrz";
if (wherelist.Count > 0)
{
sql = sql + " where " + whereSql + " order by jzrq desc";
}
else
{
MessageBox.Show("请选择检索条件！");
return;
}
DataTable dt = MsSqlHelper.ExecuteDataTable(sql, parametlist.ToArray());
MzrzGridView.DataSource = dt;
toolStripStatusLabel2.Text = string.Format("共检索到{0}条记录", dt.Rows.Count.ToString());
toolStripProgressBar1.Minimum = 0;
toolStripProgressBar1.Maximum = dt.Rows.Count;
for (int i = 0; i <= dt.Rows.Count; i++)
{字符串截取 sql
toolStripProgressBar1.Value = i;
}
}

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