Question

c# winform 多条件查询 。

有3个textbox控件 ，写其中任何一个 都可以实现查询，或者两个，或者都写。查询语句如何写？
select * from T_Paiban where Num like '%" + textBox1.Text + "%' or Name like '%" + textBox2.Text + "%' or TheWeek like like '%" + textBox3.Text + "%';

貌似当我textbox2和textbox3 为空时 就出错。怎么改？

Answer 1

String sql = select * from T_Paiban ;
String condition="";
if(textBox1.Text.Trim()!="")
condition=" Num like '%" + textBox1.Text + "%' ";
if( textBox2.Text.Trim()!=""){
if(condition.Length>0){
condition+=“ or ”;
}
condition+="Name like '%" + textBox2.Text + "%'"
}
if( textBox3.Text.Trim()!=""){
if(condition.Length>0){
condition+=“ or ”;
}
condition+="TheWeek like '%" + textBox3.Text + "%'"
}
if(condition!="")
sql+=" where "+condition;

Answer 2

string sql="select * from table name where 1=1 ";
if(!tb1.text.Equals(string.empty))
{
sql=sql+"and field1='"+tb1.text+"'";
}
if(!tb2.text.Equals(string.empty))
{
sql=sql+"and field2='"+tb2.text+"'";
}
...
sqlHelper.ExecuteDataSet(sql);

Answer 3

这个不需要修改啊。
就是在进行SQL执行前，进行判断
如：if(!String.IsNullOrEmpty( textBox1.Text ) || !String.IsNullOrEmpty( textBox2.Text ) || )
{
// Do Something
}