In this section: |
When the server accesses a data source, it needs to know how to interpret the data stored there. For each data source the server will access, you create a synonym that describes the structure of the data source and the server mapping of the Microsoft Access data types.
How to: Reference: |
Synonyms define unique names (or aliases) for each Microsoft Access table or view that is accessible from the server. Synonyms are useful because they hide the underlying data source location and identity from client applications. They also provide support for extended metadata features of the server, such as virtual fields and additional security mechanisms.
Using synonyms allows an object to be moved or renamed while allowing client applications to continue functioning without modification. The only modification required is a redefinition of the synonym on the server. The result of creating a synonym is a Master File and an Access File, which represent the server metadata.
To create a synonym, you must have previously configured the adapter. You can create a synonym from the Applications or Adapters pages of the Web Console.
The Applications page opens.
The Select adapter to configure or Select connection to create synonym pane opens.
The first of a series of synonym creation panes opens.
The Status pane indicates that the synonym was created successfully.
The synonym is created and added under the specified application directory.
Note:
The following list describes the synonym creation parameters for which you can supply values.
Restrict candidates for synonym creation based on the selected object type(s): Tables, Views, External SQL Scripts, and any other supported objects.
Choosing External SQL Scripts from the drop-down list enables you to represent an SQL Query as a synonym for read-only reporting. A Synonym candidate can be any file that contains one (and only one) valid SQL Query and does not contain end-of-statement delimiters (";" or "/") and comments.
Depending on the adapter, you can further restrict your search by choosing check boxes for listed objects.
Selecting this option adds the Object Name parameters to the screen.
Type a string for filtering the object names, inserting the wildcard character (%) as needed at the beginning and/or end of the string. For example, enter: ABC% to select all objects whose names begin with the letters ABC; %ABC to select all whose names end with the letters ABC; %ABC% to select all whose names contain the letters ABC at the beginning, middle, or end.
If you specify External SQL Scripts in the Restrict Object type to field, these additional fields are displayed.
The following standard naming conventions apply for UNIX, IBM i IFS, and z/OS HFS:
On IBM i, you can use alternative IFS naming conventions to access library members. The following entry illustrates this method:
/QSYS.LIB/MYLIBRARY.LIB/MYSRC.FILE
During synonym generation, the adapter issues native API calls to obtain a list of elements in the select list and builds the Master File with a field for each element. The generated Access File references the location of the SQL script in the DATASET attribute, which contains the full path, including the name and extension of the file containing the SQL Query. For example,
DATASET=/ul/home2/apps/report3.sql
When a WebFOCUS report is created, the SQL Query is used to access data.
Select the Cardinality check box to reflect the current cardinality (number of rows or tuples) in the table during metadata creation. Cardinality is used for equi-joins. The order of retrieval is based on the size (cardinality) of the table. Smaller tables are read first.
If the cardinality of the tables to be used in the application are dynamic, it may not be beneficial to choose this setting.
To specify that the Master File created for the synonym should not contain column information, select the Dynamic columns check box.
If this option is selected, column data is retrieved dynamically from the data source at the time of the request.
Only available when External SQL Scripts is selected from the Restrict objects type to drop-down menu. When selected, a SUBQUERY keyword is added to the Access File of the generated synonym. If the corresponding SQL string is not parameterized (that is, does not contain parameter markers, such as ? or :), it will be processed as a subquery embedded into a FROM clause of the generated SELECT query. Otherwise, the setting will be ignored, and a FOC1782 warning message will be issued. The default is selected (SUBQUERY=Y).
Select an application directory. The default value is baseapp.
If you have tables with identical table names, assign a prefix or a suffix to distinguish them. For example, if you have identically named human resources and payroll tables, assign the prefix HR to distinguish the synonyms for the human resources tables. Note that the resulting synonym name cannot exceed 64 characters.
If all tables and views have unique names, leave the prefix and suffix fields blank.
To change the data type mappings from their default settings, select this check box. The customizable mappings are displayed.
For information about customizable mappings , see Microsoft Access Data Type Support.
To specify that this synonym should overwrite any earlier synonym with the same fully qualified name, select the Overwrite existing synonyms check box.
Note: The connected user must have operating system write privileges in order to recreate a synonym.
This column displays the name that will be assigned to each synonym. To assign a different name, replace the displayed value.
The object type (Table, View, and so on).
Select tables for which you wish to create synonyms:
An Adapter for Microsoft Access synonym comprises a Master File and an Access File. This is a synonym for the table nf29004.
Generated Master File nf29004.mas
FILE=NF29004, SUFFIX=SQLMAC ,$ SEGNAME=NF29004, SEGTYPE=S0 ,$ FIELD=DIVISION4, DIVISION4, I11, I4, MISSING=ON ,$ FIELD=DIVISION_NA4, DIVISION_NA4, A25, A25, MISSING=ON ,$ FIELD=DIVISION_HE4, DIVISION_HE4, I11, I4, MISSING=ON ,$
Generated Access File nf29004.acx
SEGNAME=NF29004,TABLENAME=NF29004, CONNECTION=MACDSN,KEYS=1, WRITE=YES,$
This chart describes the keywords in the Access File.
Keyword |
Description |
---|---|
SEGNAME |
Value must be identical to the SEGNAME value in the Master File. |
TABLENAME |
Identifies the Microsoft Access table name. |
CONNECTION |
Indicates a previously declared connection. The syntax is: CONNECTION=connection CONNECTION=' ' indicates access to the local database server. Absence of the CONNECTION attribute indicates access to the default database server. |
KEYS |
Indicates how many columns constitute the primary key for the table. Range is 0 to 64. Corresponds to the first n fields in the Master File segment. |
WRITE |
Specifies whether write operations are allowed against the table. |
Once you have created a synonym, you can right-click the synonym name in the Adapter navigation pane of either the Web Console or the Data Management Console to access the following options.
Option |
Description |
---|---|
Open |
Opens the Master File for viewing and editing using a graphical interface. If an Access file is used it will be also available. |
Edit as Text |
Enables you to view and manually edit the Master File synonym. Note: To update the synonym, it is strongly recommended that you use the graphical interface provided by the Open option, rather than manually editing the Master File. |
Edit Access File as Text |
Enables you to view and manually edit the Access File synonym. Note: This option is available only when an Access File is created as part of the synonym. |
Sample Data |
Retrieves up to 20 rows from the associated data source. |
Data Profiling |
Data Profiling provides the data characteristics for synonym columns. Alphanumeric columns provide the count of distinct values, total count, maximum, minimum, average length, and number of nulls. Numeric columns provide the count of distinct values, total count, maximum, minimum, average value, and number of nulls. |
Refresh Synonym (if applicable) |
Regenerates the synonym. Use this option if the underlying object has been altered. |
Data Management |
Followed by these options, if applicable: Recreate DBMS Table. Recreates the data source table. You are asked to confirm this selection before the table is regenerated. (Note that the table will be dropped and recreated. During the process, data may be lost.) Delete All Data. Deletes all existing data. You are asked to confirm this selection before the data is deleted. Insert Sample Data. Inserts specified number of sample records, populating all fields with counter values. Reorganize. Recreates the data source table preserving original data. Note: This option is not available in the Web Console. |
Impact Analysis |
Generates reports on procedures, synonyms, and columns that provide information on the flows/stored procedures available on a particular server, and the synonyms and columns they use. These reports enable you to evaluate changes before they are made by showing which components will be affected. See the Server Administration for UNIX, Windows, OpenVMS, IBM i, and z/OS manual for details about Impact Analysis reports. |
Copy |
Copies the synonym to the clipboard. |
Delete |
Deletes the synonym. You are asked to confirm this selection before the synonym is deleted. |
Cut |
Deletes the synonym and places it on the clipboard. |
Properties |
Displays the properties of the synonym, including physical location, last modified date, description, and privileges. |
The following tables describe how the server maps Microsoft Access data types.
Microsoft Access Data Types |
Server Data Type |
Remarks | |
---|---|---|---|
USAGE |
ACTUAL | ||
Date-Time Data Types | |||
General Date |
HYYMDS |
HYYMDS |
|
Long Date |
HYYMDS |
HYYMDS |
|
Medium Date |
HYYMDS |
HYYMDS |
|
Short Date |
HYYMDS |
HYYMDS |
|
Long Time |
HYYMDS |
HYYMDS |
|
Medium Time |
HYYMDS |
HYYMDS |
|
Short Time |
HYYMDS |
HYYMDS |
|
NUMBER (Subtypes) Data Types | |||
Byte (range 0 to 255) |
I6 |
I4 |
|
Integer (range of -32,768 to 32,767) |
I6 |
I4 |
|
Long Integer (range of -2,147,483,648 to 2,147,483,647) |
I11 |
I4 |
|
Single (range of -3.4*1038 to +3.4*1038) |
D20.2 |
D8 |
|
Double (range of -1.797*10308 to +1.797*10308) |
D20.2 |
D8 |
|
Decimal (-1028 to +1028-1) |
P19 |
P10 |
|
Replication ID |
A38 |
A38 |
|
CURRENCY (range of -922337203685477.5808 to +922337203685477.5808) Data Types | |||
General |
P21.4 |
P10 |
|
Currency |
P21.4 |
P10 |
|
Euro |
P21.4 |
P10 |
|
Fixed |
P21.4 |
P10 |
|
Standard |
P21.4 |
P10 |
|
Percent |
P21.4 |
P10 |
|
Scientific |
P21.4 |
P10 |
|
LOB Data Types | |||
OLE OBJECT (drawings, waveform audio files, bitmapped graphics) |
BLOB |
BLOB |
Supported through the Reportingt Server API. |
Other Data Types | |||
AUTONUMBER (Long Integer) |
I6 |
I4 |
|
YES/NO |
I11 |
I4 |
|
The following table lists how the server maps Character data types. This mapping can be changed based on the value of LONGCHAR. The default value is ALPHA. For more information, see Controlling the Mapping of Large Character Data Types.
Microsoft Access Data Type |
Remarks |
LONGCHAR ALPHA |
LONGCHAR TEXT | ||
---|---|---|---|---|---|
USAGE |
ACTUAL |
USAGE |
ACTUAL | ||
TEXT (n) |
n is an integer up to 255. |
An |
An |
An |
An |
MEMO (n) |
n is an integer, up to 256, m=2*n. |
AmV |
AmV |
AmV |
AmV |
n is an integer between 256 and 63,999, m=2*n. |
AmV |
AmV |
TX50 |
TX | |
HYPERLINK (n) Stores UNC path or URL. |
n is an integer, up to 256, m=2*n. |
AmV |
AmV |
AmV |
AmV |
n is an integer greater than 256, m=2*n. |
AmV |
AmV |
TX50 |
TX |
Note: The main purpose of the LONGCHAR setting is to provide compatibility with previous releases of the server. This SET parameter was designed to control processing of DBMS Character data types and was never intended for DBMS LOB.
How to: |
The SET parameter CONVERSION LONGCHAR controls the mapping of supported Microsoft Access data types listed below. By default, the server maps these data types as alphanumeric (A). The server data type A supports a maximum of 4096 characters for TABLE/MODIFY and 32768 characters for API applications.
ENGINE SQLMAC SET CONVERSION LONGCHAR {ALPHA|TEXT|BLOB}
where:
Indicates the adapter. You can omit this value if you previously issued the SET SQLENGINE command.
Maps the Microsoft Access data types TEXT and MEMO as alphanumeric (A). ALPHA is the default value.
Maps the Microsoft Access data types TEXT and MEMO as text (TX). Use this value for WebFOCUS applications.
For UNIX, Windows, OpenVMS, and IBM i is identical to ALPHA. That is, it maps the Microsoft Access data types TEXT and MEMO as alphanumeric (A).
For z/OS, maps the Microsoft Access data types CHAR, NCHAR, VARCHAR, VARCHAR2, NVARCHAR2, and RAW as binary large object (BLOB).
How to: |
The SET parameter NCHAR indicates whether the character set is single-byte, double-byte, or triple-byte. The NCHAR setting affects the mapping of NCHAR and NVARCHAR data types.
The following chart lists data type mappings based on the value of NCHAR.
Microsoft Access Data Type |
Remarks |
NCHAR SBCS |
NCHAR DBCS |
NCHAR TBCS | |||
---|---|---|---|---|---|---|---|
USAGE |
ACTUAL |
USAGE |
ACTUAL |
USAGE |
ACTUAL | ||
NCHAR (n) |
n is an integer between 1 and 4000 d = 2 * n t =
3 * n
|
An |
An |
Ad |
Ad |
At |
At |
NVARCHAR (n) |
n is an integer between 1 and 4000 d = 2 * n t =
3 * n
|
An |
An |
Ad |
Ad |
At |
At |
ENGINE SQLMAC SET NCHAR {SBCS|DBCS|TBCS}
where:
Indicates the adapter. You can omit this value if you previously issued the SET SQLENGINE command.
Indicates a single-byte character set. SBCS is the default value.
Indicates a double-byte character set.
Indicates a triple-byte character set.
How to: |
You can alter the length and scale of numeric columns returned by a SELECT request to the server by creating different specifications in your login profile or in a stored procedure. The conversion settings are reflected in the Master File in the USAGE and ACTUAL formats of the fields generated by CREATE SYNONYM. This affects how the fields are processed and formatted by the server.
Tip: You can change this setting manually or from the Web Console.
ENGINE SQLMAC SET CONVERSION RESET ENGINE SQLMAC SET CONVERSION format RESET ENGINE SQLMAC SET CONVERSION format [PRECISION precision [scale]] ENGINE SQLMAC SET CONVERSION format [PRECISION MAX]
where:
Indicates the adapter. You can omit this value if you previously issued the SET SQLENGINE command.
Returns any previously specified precision and scale values to the adapter defaults. If you specify RESET immediately following the SET CONVERSION command, all data types return to the defaults. If you specify RESET following a particular data type, only columns of that data type are reset.
Is any valid format supported by the data source. Possible values are:
INTEGER which indicates that the command applies only to INTEGER columns.
DECIMAL which indicates that the command applies only to DECIMAL columns.
REAL which indicates that the command applies only to single-precision floating-point columns.
Note: Only applies to DB2, CA-IDMS/SQL, Microsoft SQL Server, and Sybase.
FLOAT which indicates that the command applies only to double-precision floating-point columns.
Is the precision. Must be greater than 1 and less than or equal to the maximum allowable value for the data type (see the description of MAX).
Is the scale. This is valid with DECIMAL, FLOAT and REAL data types. If you do not specify a value for scale, the current scale setting remains in effect. The default scale value is 2.
If the scale is not required, you must set the scale to 0 (zero).
Sets the precision to the maximum allowable value for the indicated data type:
Data Type |
MAX Precision |
---|---|
INTEGER |
11 |
DECIMAL |
18 |
REAL |
9 |
FLOAT |
20 |
Note: When issuing the CREATE SYNONYM command while the CONVERSION command is active in the profile, the Master File reflects the scale and length that is set by the CONVERSION command.
However, when issuing a SELECT statement, the answer set description does not use the information in the Master File. The length and scale used for the answer set description depends on whether a CONVERSION command is in effect.
If a CONVERSION command is in effect, the answer set description uses the length and scale that is set by the CONVERSION command.
If a CONVERSION command is not in effect, the answer set description uses the actual length and scale of the data.
The following example shows how to set the precision attribute for all INTEGER and SMALLINT fields to 7:
ENGINE SQLMAC SET CONVERSION INTEGER PRECISION 7
The following example shows how to set the precision attribute for all DOUBLE PRECISION fields to 14 and the scale attribute to 3:
ENGINE SQLMAC SET CONVERSION FLOAT PRECISION 14 3
The following example shows how to set the precision attribute for all INTEGER and SMALLINT fields to the default:
ENGINE SQLMAC SET CONVERSION INTEGER RESET
The following example shows how to set the precision and scale attributes for all fields to the defaults:
ENGINE SQLMAC SET CONVERSION RESET
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