Select,Add,Update,Delete

//查询
public static DataSet select(string tableName,string whereStr)
{
    string sql = "select * from "+tableName+whereStr;
    try
    {
        return DbHelp.ExecSql(sql);
    }
    catch (Exception e1)
    {
        return null;
    }
}

//删除单条
public static int delete (string tableName,string whereStr)
{
    string sql = "delete from "+tableName+whereStr;
    try
    {
        return DbHelp.ExecSql(sql);
    }
    catch (Exception e1)
    {
        return 0;
    }
}

//删除多条
public static string deltes(DataTable dt)
{
    int i = 0;
    if (dt != null && dt.Rows.Count > 0)
    {
        foreach (DataRow row in dt.Rows) //遍历行
        {
            string tableName = dt.Name;
            string pk = dt.Columns[0].ColumnName.ToString(); //获取第一列名（主键列）
            string pkValue = row[0].ToString(); //获取第一行的（主键值）
            string sql="delete from "+tableNmae+" where "+pk+" = ‘"+pkValue+"‘";

            try
            {
                i = i + DbHelp.ExecSql(sql);
            }
            catch (Exception e1)
            {
                return e1.Massage.ToString()+sql;
            }

        }
        return "删除"+i.ToString()+"条信息";
    }
    else
    {
        return "删除0行";
    }

}

//遍历dataTable新增
public static string add(DataTable dt)
{
    int k=0;
    if (dt != null && dt.Rows.Count > 0)
    {
        foreach (DataRow row in dt.Rows) //遍历行
        {
            string tableName = dt.Name;
            string pk = dt.Columns[0].ColumnName.ToString(); //获取第一列名（主键列）
            string pkValue = row[0].ToString(); //获取第一行的（主键值）
            string sql="insert into "+tableNmae+" values(";
            string sql1 = pk;
            string sql2 = "‘"+pkValue+"‘";
            for (int i = 1; i < dt.Columns.Count; i++) //从1开始，因为第一列为主键值
            {
                sql1 = sql1 + ","+dt.Columns[i].ColumnName.ToString();  //拼列明
                sql2 = sql2 + ",‘"+row[i].ToString()+"‘";  //拼值
                //sql1 = sql1 + dt.Columns[i].ColumnName + "= ‘" + row[i].ToString() + "‘,";//列名+列值
            }
            sql = sql + sql1 +") values("+sql2 +")";
            try
            {
                k = k+DbHelp.ExecSql(sql);
            }
            catch (Exception e1)
            {
                return e1.Massage.ToString()+sql;
            }
        }
        return "新增"+k.ToString()+"条信息";
    }
    return "新增0条信息";
}

//遍历dataTable修改
public static string add(DataTable dt)
{
    int k = 0;
    if (dt != null && dt.Rows.Count > 0)
    {
        foreach (DataRow row in dt.Rows) //遍历行
        {
            string tableName = dt.Name;
            string pk = dt.Columns[0].ColumnName.ToString(); //获取第一列名（主键列）
            string pkValue = row[0].ToString(); //获取第一行的（主键值）
            string sql="update "+tableNmae+" set ";
            for (int i = 1; i < dt.Columns.Count; i++) //从1开始，因为第一列为主键值
            {
                sql1 = sql1 + dt.Columns[i].ColumnName + "= ‘" + row[i].ToString() + "‘,";//列名+列值
            }
            sql = sql.Substring(0,sql.Length -1) + " where "+pk+" = ‘"+pkValue+"‘";
            try
            {
                k = k+DbHelp.ExecSql(sql);
            }
            catch (Exception e1)
            {
                return e1.Massage.ToString()+sql;
            }
        }
        return "修改"+k.ToString()+"条信息";
    }
    return "修改0条信息";
}