C# 中sql语句

[sd4062825]

select * from ad where 用户名 like "+this.ad.ToString()+" ;
其中ad为string类型变量
运行时提示列名ad无效
怎么改？

[zhujiazhi]

select * from ad where 用户名 like '%"+this.ad.ToString()+"%' ;
加个引号的

[bancxc]

select * from ad where 用户名 like '%"+this.ad.ToString()+"%' ;

[koukoujiayi]

string sql="select * from ad where 用户名 like '%"+this.ad.ToString()+"%'" ;

[wuyq11]

string sql="select * from ad where 用户名 like '%"+this.ad.ToString()+"%'" ;

[星星之火leo]

string sql="select * from ad where 用户名 like '%"+this.ad.ToString()+"%'" ;