有一局域网,ACCESS数据库在其中一台中,我现在要在其它电脑VB中写程序对ACCESS数据库一个表增加30个单精度型字段,请问具体如何操作?另一个问题(有关查询条件的问题)也是一台电脑对另一台电脑上的ACCESS数据库中一个表进行查询(以时间进行查询),这个表中一天内有24条记录,也就是一个小时一条记录,有一个短日期字段和一个日期时间字段,我现在要做一个报表,这个报表中要有查询当天的24条记录再加上前一天的最后一条记录请问这个查询条件应该怎么写?
调试欢乐多
我认为你可以这样
select * from 表 where sj='今天'
union
select max(sj),* from 表 where sj='昨天'
还有一种方法,我没有试过
select * from 表 where (sj='今天') or (sj='昨天' and max(sj))
'菜单“工程”-->"引用"-->"Microsoft ActiveX Data Objects 2.5 Library"
'菜单“工程”-->"引用"-->Microsoft ADO Ext.2.7 for DDL ado Security
Dim cat As ADOX.Catalog
Set cat = New ADOX.Catalog
cat.Create ("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + App.Path & "\newdata.mdb" + ";")
MsgBox "数据库已经创建成功!"
Dim tbl As ADOX.Table
Set tbl = New ADOX.Table
tbl.ParentCatalog = cat
tbl.Name = "MyTable"
'增加一个自动增长的字段
Dim col As ADOX.Column
Set col = New ADOX.Column
col.ParentCatalog = cat
col.Type = ADOX.DataTypeEnum.adInteger ' // 必须先设置字段类型
col.Name = "id"
col.Properties("Jet OLEDB:Allow Zero Length").Value = False
col.Properties("AutoIncrement").Value = True
tbl.Columns.Append col, ADOX.DataTypeEnum.adInteger, 0
'增加一个文本字段
Dim col2 As ADOX.Column
Set col2 = New ADOX.Column
col2.ParentCatalog = cat
col2.Name = "Description"
col2.Properties("Jet OLEDB:Allow Zero Length").Value = False
tbl.Columns.Append col2, ADOX.DataTypeEnum.adVarChar, 25
'增加一个货币型字段
Dim col4 As ADOX.Column
Set col4 = New ADOX.Column
col4.ParentCatalog = cat
col4.Type = ADOX.DataTypeEnum.adCurrency
col4.Name = "xx"
tbl.Columns.Append col4, ADOX.DataTypeEnum.adCurrency
'增加一个OLE字段
Dim col5 As ADOX.Column
Set col5 = New ADOX.Column
col5.ParentCatalog = cat
col5.Type = ADOX.DataTypeEnum.adLongVarBinary
col5.Name = "OLD_FLD"
tbl.Columns.Append col5, ADOX.DataTypeEnum.adLongVarBinary
'增加一个数值型字段
Dim col3 As ADOX.Column
Set col3 = New ADOX.Column
col3.ParentCatalog = cat
col3.Type = ADOX.DataTypeEnum.adDouble
col3.Name = "ll"
tbl.Columns.Append col3, ADOX.DataTypeEnum.adDouble
Dim p As ADOX.Property
For Each p In col3.Properties
Debug.Print p.Name & ":" & p.Value & ":" & p.Type & ":" & p.Attributes
Next
'设置主键
tbl.Keys.Append "PrimaryKey", ADOX.KeyTypeEnum.adKeyPrimary, "id", "", ""
cat.Tables.Append tbl
MsgBox "数据库表:" + tbl.Name + "已经创建成功!"
Set tbl = Nothing
Set cat = Nothing
Dim adocon As ADODB.Connection
Set adocon = New ADODB.Connection
adocon.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\newdata.mdb;" & "Mode=Share Deny Read|Share Deny Write;Persist Security Info=False;Jet OLEDB:Database Password="
Set cat = New ADOX.Catalog
Set cat.ActiveConnection = adocon
For i = 0 To cat.Tables.Count - 1
Debug.Print cat.Tables(i).Name '取出表名
If cat.Tables(i).Name = "MyTable" Then
For j = 0 To cat.Tables(i).Columns.Count - 1
Debug.Print cat.Tables(i).Columns(j) '取出列名
Debug.Print cat.Tables(i).Columns(j).Type '取出数据类型
For Each p In cat.Tables(i).Columns(j).Properties
Debug.Print p.Type & p.Name & p.Attributes '取出列的属性
Next
Next j
End If
Next i
cat.Tables.Item("MyTable").Columns("ll").Properties("Jet OLEDB:Allow Zero Length").Value = True '设置零长度正确
Set cat = Nothing
adocon.Close
Set adocon = Nothing
End Sub