FileAdapter.OpenSimpleQuery Method
Definition
Namespace: ASNA.DataGate.Client
Assembly: ASNA.QSys.DataGate.Client.dll
Opens the FileAdapter with a simple query.
### void OpenSimpleQuery(AdgDataSet& ds, string queryFile, string query, String[] keyNames, KeyUsages[] keyFlags)
Parameters
| Type | Parameter name | Description |
|---|---|---|
| AdgDataSet& | ds | The AdgDataSet to use for the FileAdapter. |
| String | queryFile | The file to query. |
| String | query | The query to execute. |
| String[] | keyNames | The names of the keys to use in the query. |
| KeyUsages[] | keyFlags | The flags to use for the keys in the query. |
Remarks
OpenSimpleQuery opens the file and creates an AdgDataSet instance. This AdgDataSet is suitable for passing to FileAdapter access methods where file record data is processed. The AdgDataSet returned by OpenSimpleQuery is guaranteed to reflect record formats of the query file.
Selection expressions are evaluated during file open time. Therefore, a runtime error will be generated during the opening of the file when a selection expression error is encountered.
The selection criteria is specified as a single expression describing the values used to determine which records are selected. Any logical expression formed using relational operators can be specified (such as equal and/or not equal). The syntax of this expression is identical to that used for defining select/omit expressions when creating a logical file.
An retrival order sequence can also be provided by specifying the key fields via the KeyNams parameter. Sequential reading through the file adapter will retrive records according to the KeyNames and KeyFlags.
Note that the length of the KeyNames and KeyFlags array parameters should be equal.