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· *** 作系统平台
跨越多种 *** 作系统平台,可运行于Windows、Linux、Solaris等 *** 作系统平台上,客户端与服务器都可跨越 *** 作系统平台。
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· *** 作符
· 表达式
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· SQL语句
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· OLE DB
· ODBC
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(4)数据库文档
· 联机帮助
1、查看当前用户连接数:select connections()2、修改用户new_user的最大并发连接数为50:alter user new_user with connection limit 50
3、修改用户new_user的最大连接时间为2小时:alter user new_user with connection duration 120
4、修改用户new_user的最大空闲时间为2小时:alter user new_user with connect idle time 120
重点是下面配置文件的修改,修改KingBaseES\data下的kingbase.conf的最大并发连接数:
max_connections = 50
最后,重启金仓数据库实例,例如:使用ikrms.exe工具:
start kingbase kingbasees1(实例名)
stop kingbase kingbasees1(实例名)
金仓数据库 ?-----------------------给你一段C# *** 作sqlserver的示例代码
1.数据库建表,
create table mytable(
pkid nvarchar(40) not null,
a nvarchar(40) null
)
insert into mytable(pkid,a) values(newid(),'测试')
2.新建对应此表的实体类
[Serializable]
public class mytable
{
private String _pkid = ""
public String pkid
{
get { return _pkid}
set { _pkid = value}
}
private String _a = ""
public String a
{
get { return _a}
set { _a = value}
}
}
3.新建 *** 作类:
public class mytableDAO
{
private String _ConnectionString
public mytableDAO(String ConnectionString)
{
this._ConnectionString = ConnectionString
}
public int New(Entities.MsgRecord obj)
{
String sql = "insert into mytable(pkid,a) values(@pkid,@a)"
SqlConnection cn = new SqlConnection(this._ConnectionString)
SqlCommand cmd = new SqlCommand(sql, cn)
cmd.Parameters.AddWithValue("@a", obj.a)
cmd.Parameters.AddWithValue("@pkid",
String.Empty.Equals(obj.pkid) ? System.Guid.NewGuid().ToString() : obj.pkid)
try
{
if (cn.State != ConnectionState.Open)
cn.Open()
return cmd.ExecuteNonQuery()
}
catch
{
return -1
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close()
}
}
public int Update(Entities.mytable obj)
{
String sql = "Update mytable Set a=@a Where pkid=@ObjectID"
SqlConnection cn = new SqlConnection(this._ConnectionString)
SqlCommand cmd = new SqlCommand(sql, cn)
cmd.Parameters.AddWithValue("@a", obj.a)
cmd.Parameters.AddWithValue("@pkid", obj.pkid)
try
{
if (cn.State != ConnectionState.Open)
cn.Open()
return cmd.ExecuteNonQuery()
}
catch
{
return -1
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close()
}
}
public int Del(Entities.mytable obj)
{
String sql = "delete from mytable Where pkid=@ObjectID"
SqlConnection cn = new SqlConnection(this._ConnectionString)
SqlCommand cmd = new SqlCommand(sql, cn)
cmd.Parameters.AddWithValue("@ObjectID", obj.pkid)
try
{
if (cn.State != ConnectionState.Open)
cn.Open()
return cmd.ExecuteNonQuery()
}
catch
{
return -1
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close()
}
}
public int Del(String where)
{
String sql = String.Format("delete from mytable Where {0}", where.ToLower().Replace("update", "").Replace("delete", ""))
SqlConnection cn = new SqlConnection(this._ConnectionString)
SqlCommand cmd = new SqlCommand(sql, cn)
try
{
if (cn.State != ConnectionState.Open)
cn.Open()
return cmd.ExecuteNonQuery()
}
catch
{
return -1
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close()
}
}
public DataTable Query(String where)
{
String sql = String.Format("select * from mytable Where {0}", where.ToLower().Replace("update", "").Replace("delete", "").Replace("insert", "").Replace("", "").Replace("--", "").Replace("exec", ""))
try
{
SqlDataAdapter da = new SqlDataAdapter(sql, new SqlConnection(this._ConnectionString))
DataTable dt = new DataTable()
da.Fill(dt)
return dt
}
catch
{
return null
}
}
}
4.在ui中调用:
4.1 新增:
private void NewData()
{
String conn=System.Configuration.ConfigurationManager.ConnectionStrings["dbCon"].ConnectionString
mytableDao dao=new mytableDao(conn)
mytable obj=new mytable()
obj.a=this.txtbox_a.Text
obj.b=this.txtbox_b.Text
obj.c=this.txtbox_c.Text
dao.New(obj)
}
4.2 取数据绑定GridView
private void LoadData_InitGridView()
{
String conn=System.Configuration.ConfigurationManager.ConnectionStrings["dbCon"].ConnectionString
mytableDao dao=new mytableDao(conn)
Table dt=dao.Query(String.Format(" a ='{0}'",this.txtbox_a.Text))
//gridview
this.GridView1.DataSource=dt
this.GridView1.DataBind()
//textbox control
this.textbox_a.Text=dt.Rows[0][0].ToString()
}
4.3删除
private void Del()
{
String conn=System.Configuration.ConfigurationManager.ConnectionStrings["dbCon"].ConnectionString
mytableDao dao=new mytableDao(conn)
//根据条件删除指定记录
dao.Del(where)
}
4.4更新
private void Update()
{
String conn=System.Configuration.ConfigurationManager.ConnectionStrings["dbCon"].ConnectionString
mytableDao dao=new mytableDao(conn)
dao.Update(obj)//obj 为mytable的一个实例:需要更新的
}
5.配置文件中连接信息
<connectionStrings>
<add name="dbCon" connectionString="Data Source=192.168.1.100Initial Catalog=NorthwindUser ID=saPassWord=sa" providerName="System.Data.SqlClient"/>
</connectionStrings>
6.读取连接信息
System.Configuration.ConfigurationManager.ConnectionStrings["dbCon"].ConnectionString
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