C# DataTable 使用linq 动态拼接查询

//动态拼接多个参数，可以更加条件重新更改
//typeof(string)是数据类型
private static Func<DataRow, bool> ExoerssionCondition(DataRow dr, List<CompareConfig> columnList)

        {
            ParameterExpression r = Expression.Parameter(typeof(DataRow), "r"); //DataRow参数:r
            Expression con = Expression.Constant(true); //All nested conditions
            foreach (var item in columnList)
            { 
                ConstantExpression expFieldName = Expression.Constant(item.TargetField, typeof(string)); //"Height" 字符串常量
                ConstantExpression expValue= Expression.Constant(dr[item.SourceField].ToString(), typeof(string));//创建float常量5.0 }
                List<Expression> list = new List<Expression>();
                list.Add(r); list.Add(expFieldName); //参数列表：DataRow, "Height"
                MethodInfo mi = typeof(DataRowExtensions).GetMethod("Field", new Type[] { typeof(DataRow), typeof(string) }).MakeGenericMethod(typeof(string));
                MethodCallExpression MC = Expression.Call(null, mi, list); //创建MethodCallExpression

                Expression SingleExpCon = Expression.Equal(MC, expValue);
                con = Expression.And(con, SingleExpCon); 
            } 
            var expLam = Expression.Lambda<Func<DataRow, bool>>(con, r);
            return expLam.Compile();  
        }

参考例子：https://blog.csdn.net/alai7150/article/details/103086231

标签：string,C#,list,linq,DataRow,typeof,Expression,DataTable,con
来源： https://www.cnblogs.com/jerrywublogs/p/14307481.html