Thuộc tính ADO
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Thuộc tính Thuộc tính đặt hoặc trả về một giá trị dài cho biết một hoặc nhiều đặc điểm của một đối tượng.
Lưu ý: Khi thiết lập nhiều thuộc tính có thể tính tổng các giá trị.
| Object | Description of the Attributes Property |
|---|---|
| Connection | The Attributes property has read/write permissions on a Connection object. Its value can be the sum of one or more XactAttributeEnum values. Default value is 0 |
| Parameter | The Attributes property has read/write permissions on a Parameter object. Its value can be the sum of one or more ParameterAttributesEnum values. Default value is adParamSigned |
| Field | The Attributes property has read/write permissions when used to create a Recordset, but it has read-only permissions when you open an existing Recordset. Its value can be the sum of one or more FieldAttributeEnum values |
| Property | The Attributes property is read-only for a Property object. Its value can be the sum of one or more PropertyAttributesEnum values |
Cú pháp
object.Attributes Ví dụ - Đối với đối tượng Connection:
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
response.write(conn.Attributes)
conn.close
%> Ví dụ - Đối với đối tượng Trường:
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
set rs = Server.CreateObject("ADODB.Recordset")
rs.open "Select * from orders", conn
set f=Server.CreateObject("ADODB.Field")
'Display the field attributes of the Orders Table
for each f in rs.Fields
response.write("Attr:" & f.Attributes & "<br>")
response.write("Name:" & f.Name & "<br>")
response.write("Value:" & f.Value & "<br>")
Next
rs.Close
conn.close
set rs=nothing
set conn=nothing
%> Ví dụ - Đối với đối tượng Thuộc tính:
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
set rs = Server.CreateObject("ADODB.Recordset")
rs.open "Select * from orders", conn
set prop=Server.CreateObject("ADODB.Property")
'Display the property attributes of the Orders Table
for each prop in rs.Properties
response.write("Attr:" & prop.Attributes & "<br>")
response.write("Name:" & prop.Name & "<br>")
response.write("Value:" & prop.Value & "<br>")
next
rs.close
conn.close
set rs=nothing
set conn=nothing
%> Giá trị XactAttributionEnum
| Constant | Value | Description |
|---|---|---|
| adXactAbortRetaining | 262144 | When calling RollbackTrans it automatically starts a new transaction. |
| adXactCommitRetaining | 131072 | When calling CommitTrans it automatically starts a new transaction. |
Tham sốThuộc tínhEnum Giá trị
| Constant | Value | Description |
|---|---|---|
| adParamSigned | 16 | The parameter will accept signed values. |
| adParamNullable | 64 | The parameter will accept null values. |
| adParamLong | 128 | The parameter will accept long binary data. |
Giá trị FieldAttributionEnum
| Constant | Value | Description |
|---|---|---|
| adFldCacheDeferred | 0x1000 | Provider caches the field values and reads from the cache. |
| adFldFixed | 0x10 | Field contains fixed-length data. |
| adFldIsChapter | 0x2000 | Field contains a chapter value that specifies a child recordset. |
| adFldIsCollection | 0x40000 | The field specifies that the resource represented by the record is a collection of resources |
| adFldIsDefaultStream | 0x20000 | Field contains the default stream for the resource represented by the record. |
| adFldIsNullable | 0x20 | Field accepts null values. |
| adFldIsRowURL | 0x10000 | Field contains the URL that names the resource from the data store represented by the record. |
| adFldLong | 0x80 | Field is a long binary field. |
| adFldMayBeNull | 0x40 | You can read null values from the field. |
| adFldMayDefer | 0x2 | Field values are not retrieved from the data source with the whole record, but only when you explicitly access them. |
| adFldNegativeScale | 0x4000 | Field represents a numeric value from a column that supports negative scale values. |
| adFldRowID | 0x100 | Field contains a persistent row identifier that cannot be written to and has no meaningful value except to identify the row (such as a unique id) |
| adFldRowVersion | 0x200 | Field contains some kind of time/date stamp used to track updates. |
| adFldUnknownUpdatable | 0x8 | The provider cannot determine if you can write to the field. |
| adFldUnspecified | -1 0xFFFFFFFF | Provider does not specify the field attributes. |
| adFldUpdatable | 0x4 | You can write to the field. |
Thuộc tínhThuộc tínhEnum Giá trị
| Constant | Value | Description |
|---|---|---|
| adPropNotSupported | 0 | The property is not supported by the provider. |
| adPropRequired | 1 | The user must specify a value for this property before the data source is initialized. |
| adPropOptional | 2 | The user does not need to specify a value for this property before the data source is initialized. |
| adPropRead | 512 | The user can read the property. |
| adPropWrite | 1024 | The user can set the property. |
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