请注意下表.我想将新创建的BEST_SELLER列的默认值设置为"N".
我该怎么做呢？

Create Table Mystery
(Book_Code Char(4) Primary Key,
 Title Varchar2(40),
 Publisher_Code Char(2),
 Price Number(4,2))

请参阅下面的PL/SQL片段:

create table t23 (
    field01 number, 
    field02 number, 
    field03 char(1) 
);

示例代码段#1

declare x varchar2(2000) := '
<ArrayOfRecords>
<Record>
<Field01>130</Field01> 
<Field02>1700</Field02> 
<Field03>C</Field03> 
</Record> 
<Record>
<Field01>131</Field01> 
<Field02>1701</Field02> 
<Field03>B</Field03> 
</Record>                         
</ArrayOfRecords>';

begin
    insert
    into    T23
    SELECT  *
    FROM    XMLTABLE('/ArrayOfRecords/Record'
                PASSING xmltype(x)
                    COLUMNS 
                    Field01 number PATH 'Field01',
                    Field02 number PATH 'Field02',
                    Field03 char(1) PATH 'Field03'
            );
end;

-- The records will be here - great!
select  * from T23;

示例代码段#2

declare y varchar2(2000) := '
<ArrayOfRecords>
<Record Field01="130" Field02="1700" Field03="C" />
<Record …

我有一个问题:

select country_region, 
       country_subregion, 
       country_name, 
       calendar_year, 
       calendar_quarter_number, 
       sum(amount_sold) as amount
  from countries co join
       customers cu on co.country_id = cu.country_id join
       sales sa on cu.cust_id = sa.cust_id join
       times ti on sa.time_id = ti.time_id
 where (   co.country_region = 'Americas' 
        or co.country_region = 'Middle East'
       ) 
   and ti.calendar_year between 2000 and 2001
group by grouping sets 
(
    (country_region, country_subregion, country_name, calendar_year, calendar_quarter_number),
    (country_region, country_subregion, country_name, calendar_year),
    (country_region, country_subregion, country_name),
    (country_region, country_subregion, calendar_year, calendar_quarter_number),
    (country_region, country_subregion, calendar_year),
    (country_region, country_subregion),
    (country_region, calendar_year, calendar_quarter_number), …

我有一个客户端和服务器设置与JBoss AS 7.1.1一起运行,我有一个关于我的persistence.xml的问题.目前它看起来像这样:

<persistence>
    <persistence-unit name="GrahamsProj">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>java:jboss/datasources/WorkCenterDS</jta-data-source>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
            <property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver"/>
        </properties>
    </persistence-unit>
</persistence>

我的服务器的META-INF文件夹中有persistence.xml.我必须缺少一些属性,因为当我尝试查询我连接的数据库时,我收到此错误.

11:35:07,840 ERROR [org.jboss.ejb3.invocation] (EJB default - 1) JBAS014134: 
EJB Invocation failed on component GrahamsProjBean for method public abstract 
void grahamsprojserver.session.interfaces.GrahamsProjBeanRemote.test(): javax.ejb.EJB
Exception: java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: 
Schemas is not mapped [FROM Schemas s]

有什么我想念的吗？

我有一个datagridview,我已经设置allow user将row属性添加到false.

我还让它只能在datagridview上进行全视图选择.

用户通过按工具条的"+"按钮将行添加到数据网格.通过将数据拖动到添加了绑定导航器工具条的表单来创建DGV.

我的问题是在我的行删除代码中,我检查

private void bindingNavigatorDeleteItem_Click(object sender, EventArgs e)
{
    try
    {
        if (dgvUsers.SelectedRows.Count > 0 && dgvUsers.Rows[0].Selected)
            MessageBox.Show("You cannot remove the user admin");
        else
        {
            if (MessageBox.Show("Are you sure you want to remove the user?", "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                int code = 0;

                UserService userService = new UserService();

                if (dgvUsers.SelectedRows.Count > 0)
                {
                    int selectedrowindex = dgvUsers.SelectedCells[0].RowIndex;

                    DataGridViewRow selectedRow = dgvUsers.Rows[selectedrowindex];

                    code = (int)(selectedRow.Cells[0].Value);

                    if (GlobalClass.SessionId == "admin")
                    {
                        userService.RemoveUsers(code);
                    }
                    else
                        MessageBox.Show("Only username 'admin' …

我有一个使用MFC的现有Visual C++项目,我在Visual Studio 2008中运行.该机器刚刚设置并安装,我已从Source Control中取出项目.解决方案构建正常,但如果我进入资源文件并尝试上拉并查看对话框,我会收到消息

2 ActiveX controls could not be instantiated. Reinstall or register the controls and try again message when viewing Dialog

我不知道如何确定它抱怨哪些ActiveX控件,所以我可以尝试重新注册它们,因为它不会显示对话框.

我能够创建一个新的Dialog并在其上放置控件,但现有的不会拉起来.

String months[] = { null , "Jan" , "Feb" , "Mar" , "Apr", 
                    "May", "Jun", "Jul", "Aug", "Sep", "Oct", 
                    "Nov", "Dec" };

try
{
  System.out.print("Enter month <1 for Jan - 12 for Dec>:  ");

  m = input.nextInt();
  MonthData();
}
catch(Exception e)
{
  System.out.println("Invalid month!"); //error message to  inform user of wrong input
}   

break;

static void MonthData()
{            

  System.out.println("----------------------------------------");
  System.out.println(months[m]+" Expenditure <max 10 items>");

  try
  {
    for(int i=0; i<10; i++)
    {
      System.out.print("Enter item "+(i+1)+" <Press ENTER to exit> : "); …