Data Shaping technology - the necessary configuration data providers
Service providers can specify the name for the Connection object Provider property value, or the connection string keyword "Provider =".
Data providers can specify the name for the "Data Provider" dynamic attribute values, the dynamic properties of the Data Shaping Service for OLE DB added to the Properties collection of Connection objects. Or can also specify the connection string for the keyword "Data Provider =".
If there is no filling Recordset (For example, if all the columns forming the Recordset using NEW keyword to create), you do not need data providers. In this case the designated "Data Provider = none".
Dim cnn As New ADODB.Connection
cnn.Provider = "MSDataShape"
cnn.Open "Data Provider = MSDASQL; DSN = vfox; uid = sa; pwd = vfox; database = pubs"
Conventional Shape command
"Configuration data" is defined columns forming Recordset from the list of entries on behalf of the relationship between the filling and data to the Recordset way.
Forming the Recordset can be shown by the following types of components:
Out the type of note
Data from the data provider, or before forming Recordset by using the query command to return to the field of the Recordset.
Subset of the reference to another Recordset, known as the "subset." Out so that the definition of a subset of "the father - child" relationship is possible in this relationship of "father" is a column that contains a subset of the Recordset, "son" is a subset of the representative from the Recordset.
Total value of listed firms through the implementation of all "total function" to obtain, or sub-Recordset column of all rows. (See the following table the total function.)
Out the calculation of the value of the expression of the same line in the Recordset list of Visual Basic for Applications to the calculation of expression and access. CALC expression is a function of the parameters. (Please refer to the table below in the calculation of the expression.)
New empty fields fiction can fill in the following data. Defined using the NEW keyword. (Please refer to the table below the NEW keyword.)
Shape command may contain clause, specify the basic data provider and to return to the query command Recordset object. Query syntax depends on the basic requirements of data providers. Although ADO does not require the use of any specified query language, but usually is the use of Structured Query Language (SQL).
You can use the SQL JOIN clause linked two tables, but can be graded Recordset to express information more efficiently. JOIN created from each row of the Recordset will be redundant to repeat the information in a table. Recordset classification of multiple sub-Recordset object, each object has only one parent Recordset.
Shape command issued only by the Recordset object.
Shape commands can be nested, that is, the father of the order or the order itself can be a son of another Shape command.
Recordset classification of the position, please refer to the visit of the line classification Recordset.
Shape of the correct command syntax for more information, please refer to the shape of syntax.
Total function, CALC function and NEW keywords
Configuration data in support of the following function. chapter-alias is assigned to the operation will be included in a subset of the names out.
chapter-alias (a subset - alias) can be complete by the column-name to include a subset of a subset of each column name, all separated by a full stop. For example, if father and son set out chap1 contains amt has a number of sub-subset, then the full name that is chap1.chap2.amt.
Total Function Description
SUM (chapter-alias.column-name) calculated the value of the specified column and all.
AVG (chapter-alias.column-name) out of all the designated calculation of average value.
MAX (chapter-alias.column-name) out in the calculation of the maximum specified.
MIN (chapter-alias.column-name) out in the calculation of the minimum specified.
COUNT (chapter-alias [. Column-name]) calculation of the specified alias or list the number of Bank of China.
STDEV (chapter-alias.column-name) calculation of the column specified in the standard deviation.
ANY (chapter-alias.column-name) out of the value (the value of listed firms in all are the same).
Calculation of expression that
CALC (expression) the calculation of arbitrary expressions, but only contains the CALC function Recordset line. Can be any Visual Basic for Applications (VBA) function or expression.
NEW keyword description
NEW (field type [(width | scale] [, precision])] will empty out the specified type is added to the Recordset.
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