C#中select from where

where后面可以加多个条件么 具体语句应该怎么写呢 下面是一个条件的 如果要加其他or条件怎么加呢
string sql = "select * from WeldingDB where 母材='" + textBox12.Text.Trim() + "'";

select * from XX where ID in(1,19);
select * from XX where ID=1 or ID=19;

string sql = "select * from WeldingDB where 母材 in('" + textBox12.Text.Trim() +"','"+ textBox12.Text.Trim() "')";

标准sql语句写法为： select * from hu_product where cid in(3,5,6,1,2) 所以proidlist定义成string类型，传递以,间隔的数字就行如: proidlist="1,5,6,7,9"; sqlcommand mycmd = new sqlcommand("select count(id) as co from hu_product where cid in (" + proidlist + ")", conn); 这样就行的。