Question

我已经简化了我的问题并创建了这个示例以便更好地说明。

我的表：

CREATE TABLE `table_company` (
  `source_id` INT(10) UNSIGNED NOT NULL,
  `company_id` INT(10) UNSIGNED NOT NULL,
  `clicks` INT(10) UNSIGNED NOT NULL,
  PRIMARY KEY (`source_id`,`company_id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;

我的数据：

INSERT INTO table_company VALUES
(1,100,8),(2,100,7),(3,200,9),(4,300,3),(5,100,4),(6,400,5),(7,100,10),(8,500,4),(9,500,9),(10,400,9);


SELECT source_id,company_id,AVG(clicks) AS avg_click FROM table_company
GROUP BY source_id,company_id
ORDER BY avg_click DESC;

给我：

source_id  company_id  avg_click  
---------  ----------  -----------
        7         100      10.0000
        3         200       9.0000
        9         500       9.0000
       10         400       9.0000
        1         100       8.0000
        2         100       7.0000
        6         400       5.0000
        5         100       4.0000
        8         500       4.0000
        4         300       3.0000

我想写一个查询给我：

source_id  company_id  avg_click  
---------  ----------  -----------
        7         100      10.0000
        3         200       9.0000
        9         500       9.0000
       10         400       9.0000
        4         300       3.0000

即。只保留具有MAX（avg_click）

的company_id

Answer 1

SELECT source_id, company_id, MAX(avg_click) as max_click FROM 
(SELECT source_id,company_id,AVG(clicks) AS avg_click FROM table_company
GROUP BY source_id,company_id
ORDER BY avg_click DESC) tmp
GROUP BY company_id

Answer 2

 SELECT MAx(source_id), company_id, MAX(avg_click)
 from (SELECT source_id,company_id,AVG(clicks) AS avg_click FROM #table_company 
    GROUP BY source_id,company_id 
    )as tbl
 GROUP by company_id

Answer 3

您可以使用相关性：

    <asp:GridView runat="server" ID="gridview2" AutoGenerateColumns="false" >
<Columns>
<asp:BoundField DataField="weekofyear" HeaderText="Week" />
<asp:BoundField DataField="supportname" HeaderText="Name" />
<asp:BoundField DataField="supid" HeaderText="SupportIDName" Visible="false"/>
<asp:TemplateField>
    <ItemTemplate>
        <asp:CheckBox ID="TicketCompleted" runat="server" AutoPostBack="true" OnCheckedChanged="TicketCompletedCompleted_Click" Checked='<%# Convert.ToBoolean(Eval("TicketCompleted")) %>' />
    </ItemTemplate>
</asp:TemplateField>
</Columns>

您也可以使用WITH子句：

protected void TicketCompleted_Click(object sender, EventArgs e)
{
foreach (GridViewRow row in dgRD.Rows)
{
    if (row.RowType == DataControlRowType.DataRow)
    {
        //Below captures the checkbox value (yes or no)
        CheckBox chk = (CheckBox)row.FindControl("TicketCompleted");                    
        if (chk.Checked)
        {
            //Here is where I will run the update
        }
    }
}

SQL。获得最大值（平均（列））

3 个答案: