日常问题总结（2）

来源：互联网发布：游戏算法书籍编辑：程序博客网时间：2024/06/05 18:34

SQL中的cast()函数

CAST函数用于将某种数据类型的表达式显式转换为另一种数据类型。CAST()函数的参数是一个表达式，它包括用AS关键字分隔的源值和目标数据类型。

语法：

CAST (expression AS data_type)

例如：

select price,quantity,total,status,remark ,sa.orderid,
'国家:'+ss.country+'，套餐天数：'+CAST( ss.days as varchar)+'，套餐内容：'+ss.simcontent+'，充值参加价：'+CAST( ss.simprice as varchar)+'RMB' as shopconect
from sales as sa,simshop as ss
where sa.simid=ss.simID

sql中select过程，将多个字段合并为一个字段显示，为a字段+b字段,如上面的sql语句中所示

c#中获取当前时间格式为120202120101样式的语句

string ordertime = System.DateTime.Now.ToString("yyMMddHHmmss");

gridview里模板列删除事件

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnRowDeleting="GridView1_RowDeleting">

<Columns>

<asp:TemplateField>
<ItemTemplate>
<asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="images/delete.ico" Width="20" Height="20" border="0" longdesc="#" OnClick="ImageButton1_Click1" />
</ItemTemplate>
<ItemStyle HorizontalAlign="Center" />
</asp:TemplateField>
</Columns>
</asp:GridView>

protected void ImageButton1_Click1(object sender, ImageClickEventArgs e)
{
string ordertime = System.DateTime.Now.ToString("yyMMddHHmmss");
ImageButton btn = sender as ImageButton;
GridViewRow row = btn.NamingContainer as GridViewRow;
int id = row.RowIndex;
GridView1.SelectedIndex = id;
string obj = GridView1.Rows[GridView1.SelectedIndex].Cells[0].Text.ToString();
string sql = "update sales set orderflag='1', flagtime='{0}' where orderid='{1}'";
sql = string.Format(sql, obj,ordertime);
int ret = SqlHelper.ExecuteNonQuery(sql);
if (ret == 1)
{
ScriptManager.RegisterClientScriptBlock(this, GetType(), "aaa", "alert('订单删除成功');", true);
}
else
{
ScriptManager.RegisterClientScriptBlock(this, GetType(), "aaa", "alert('系统异常，订单删除失败');", true);
}
databind();

}

sql server约束查找

参考http://www.cnblogs.com/henw/archive/2012/07/09/2582724.html

FK_ 外键

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
主键约束
SELECT
  tab.name AS [表名],
  idx.name AS [主键名称],
  col.name AS [主键列名]
FROM
  sys.indexes idx
    JOIN sys.index_columns idxCol 
      ON (idx.object_id = idxCol.object_id 
          AND idx.index_id = idxCol.index_id 
          AND idx.is_primary_key = 1)
    JOIN sys.tables tab
      ON (idx.object_id = tab.object_id)
    JOIN sys.columns col
      ON (idx.object_id = col.object_id
          AND idxCol.column_id = col.column_id);
 
唯一约束
SELECT
  tab.name AS [表名],
  idx.name AS [约束名称],
  col.name AS [约束列名]
FROM
  sys.indexes idx
    JOIN sys.index_columns idxCol 
      ON (idx.object_id = idxCol.object_id 
          AND idx.index_id = idxCol.index_id 
          AND idx.is_unique_constraint = 1)
    JOIN sys.tables tab
      ON (idx.object_id = tab.object_id)
    JOIN sys.columns col
      ON (idx.object_id = col.object_id
          AND idxCol.column_id = col.column_id);
 
外键约束
select
  oSub.name  AS  [子表名称],
  fk.name AS  [外键名称],
  SubCol.name AS [子表列名],
  oMain.name  AS  [主表名称],
  MainCol.name AS [主表列名]
from
  sys.foreign_keys fk  
    JOIN sys.all_objects oSub  
        ON (fk.parent_object_id = oSub.object_id)
    JOIN sys.all_objects oMain 
        ON (fk.referenced_object_id = oMain.object_id)
    JOIN sys.foreign_key_columns fkCols 
        ON (fk.object_id = fkCols.constraint_object_id)
    JOIN sys.columns SubCol 
        ON (oSub.object_id = SubCol.object_id  
            AND fkCols.parent_column_id = SubCol.column_id)
    JOIN sys.columns MainCol 
        ON (oMain.object_id = MainCol.object_id  
            AND fkCols.referenced_column_id = MainCol.column_id)
 
Check约束
SELECT
  tab.name AS [表名],
  chk.name AS [Check约束名],
  col.name AS [列名],
  chk.definition
FROM
  sys.check_constraints chk
    JOIN sys.tables tab
      ON (chk.parent_object_id = tab.object_id)
    JOIN sys.columns col
      ON (chk.parent_object_id = col.object_id
          AND chk.parent_column_id = col.column_id)

添加外键约束

alter table sales
add constraint id_sim
foreign key (simid)
references simshop(simid)

删除约束

alter table sales
drop constraint id_sim

阅读全文

0 0