Introduction to Database Connection
- (Database connection is a feature of the Professional edition only)
In OCAD you can link objects to information in the database about this object. A database normally consists of several tables. In flat file databases like dBase, each table is a file. All tables in a folder form a database. In other databases like Access or in spreadsheet programs like Excel all tables of the database are in the same file. A table consists of records. A record contains the information about one OCAD object. A record consists of fields which contain the information. A special field is the key field. It normally contains a number to identify the record. To link an OCAD object to a record the number in the key field is stored in the object.
To connect to a table OCAD uses a dataset. The dataset contains the link to the database, the name of the table, the name of the key field and information about other special fields. You can have several datasets for the same OCAD map. To create a dataset choose Manage Database connection from the Database menu. You can access on databases via ODBC (Open Manage Database Connection). This is an interface to connect to all kind of databases.
Manage Database Connections
- Choose this command to create and edit datasets. A dataset makes the connection to a database. It defines the table to use in the database and inside the table the key field. The key is used to connect an OCAD object to a record in the table. Each object must have a unique key.
- You can use several datasets for one map. On the left side of the dialog box, there is a list of the datasets.
- The dialog box has 3 pages:
- General: General settings for the selected dataset.
- Secondary tables: Create/edit secondary tables.
- Special fields: Define special fields.
ADD or DELETE
Choose this command to create a dBase table and to add or remove fields in a dBase table. In dBase each table is a file. The dBase Table dialog box appears.
- This box lists the fields of the dBase table. Each field is displayed in a line. Select a field if you want to remove it.
- Name:: Enter here the name for the field. The name must start with a letter and may contain up to 10 letters and numbers. Letters are converted to capital letters.
- Type:: Choose character (C), number (N) or float (F).
- Length:: Enter here the number of characters for the field.
- Decimals:: This filed is only active if the data type is Float. Enter the number of decimal places.
- Move Up: Click this icon to move the selected field one line upwards.
- Move Down: Click this icon to move the selected field one line downwards.
- Insert: Click this button to add a field. After adding the new field, the dBase table is restructured. Existing information is preserved.
- Delete: Click this button to delete the selected field.
- New table: Click this button to create a new dBase table. The new table will contain 6 predefined fields: ID (intended for the key field), SYMBOL (symbol field), TEXT (text field) and URL (intended for Internet address). You can add additional fields.
- Open table: Click this button to open an existing dBase table.
Choose this command in Manage Database Connections to create a new ODBC data source or to modify an existing data source. The ODBC Data Source Administrator is started. This is a Microsoft program and contains its own online help. Here just some hints. Normally you create a new User DNS.
- For a connection to an Excel file, you select the Excel driver and the Excel (*.xls) file.
- For a connection to an Access database, you select the Access driver and the Access (*.mdb) file.
- For a connection to a flat file database like dBase you do not select the dBase file. Instead you select the folder where the dBase file is.
Creating a New Database Table
For certain functions you need a database table (for instance for the Find and the Hotspot functions in Internet maps). If the Database does not yet exist, you can easily create a database table for an existing OCAD map.
Create a dBase file
- Choose Manage Database connections from the Database menu.
- Click the New button.
- Enter in the field Name the name of the dataset.
- In the field Data source choose Create new dBase file and click OK. A file dialog box appears.
- Leave the file name as proposed or change it to your needs and click OK.
- Now you have created a dBase table with 6 fields ID (intended as key field), SYMBOL (symbol field), TEXT (text field), URL (link field), X (for horizontal coordinate) and Y (for vertical coordinate). For many cases, such as an Internet map this is enough. If you want to add additional fields choose dBase from the Database menu.
- -Create new dBase file: Select this option if you want to create a new empty dBase table for the dataset. A new dBase file will be created. To add fields or to modify the existing fields choose dBase from the Database menu.
- -Use existing data source: Select this option if the database or table already exists.
- Hint for dBase files: If you do not have installed the "Borland Database Engine" (BDE) then only filename with less than 8 characters are allowed. For example 'test5678.dbf'. You can if the BDE is installed in the Map Information dialog. The free BDE can be downloaded from the www and installed.
Linking objects to the table
- Let's assume that you want to create an Internet map with street find function. All street names must have a record in the table and must be linked to this table. OCAD provides a quick way to create these links.
- Select All Symbols used for street names.
- Choose Create Links from the Database menu.
- Select the dataset, if the map has several datasets and click OK.
- Now all street names are linked and the map is ready to create an Internet map with street find function.
Link Object dialog box
This dialog box appears when clicking the Link button in the database box on the right side of the screen.
- Dataset: Select here the dataset to be used for the link.
- Key: Enter here a value for the key field in the database table. The key points to a record in the table.
- Create new record: Activate this box if a new record should be created in the database table for this object.
- Remove: Click this button to remove an existing link.
Linking an Object to a Database
To link an object to a database you must have created a dataset.
Proceed as follows:
- Select the object
- Click the Link button in the database box on the right side of the screen. The Link Object dialog box appears.
This dialog box appears when clicking the Find button in the database box on the right side of the screen. This function lets you search for an object with a specified key value. If the function is successful, the object is marked in the map.
- Dataset: Select here the dataset to be used.
- Key: Enter here the value of the key to be found.
Select Database Object dialog box
This dialog box appears when clicking the SQL Query button in the database box on the right side of the screen.
This function lets you search for object(s) with linked database records. Selected objects are marked in the map and linked database records are shown in a table.
- Dataset: Select the dataset to be used.
- Field: Choose a field of the selected dataset. When you double-click on a field name it is added to the SQL statement box.
- Operator: Select an operator. When you double-click on an operator it is added to the SQL statement box.
- Value: Select a Value. When you double-click on a value it is added to the SQL statement box.
SQL Statement: The SQL statement should always contain the components FIELD - OPERATOR - VALUE (ex. Length > 430).
Click Select button to start the database query.
Assign Symbols, Texts and Angles
Choose this command after importing a Shape file. After importing the objects have no symbol assigned and appear gray (as unsymbolized objects). With this command you can use the information in the dBase table to assign OCAD symbols to the objects.
Click Symbols, Texts or Angles in Database menu. The appropriate dialog box appears
In this dialog box you can create a list of conditions. You can save the list to a condition file (*.cnt) for later use. You can load an existing condition file to modify or execute it.
- Dataset: Select here the dataset which should be used to assign symbols. Check All to execute the condition for all datasets.
- DLoad: Click this button to load an existing condition file (*.cnt).
- DSave: Click this button to save the changes to a condition file (*.cnt).
- DSave as: Click this button to save the changes to a different condition file (*.cnt).
- DSymbol: Select here a symbol. For those objects the condition is fulfilled, the symbol number will be assigned.
- DCondition: Enter the condition here.
- DMove up: Click this button to move up the selected condition.
- DMove down: Click this button to move down the selected condition.
- DAdd: Click this button to add a condition to the list.
- DDelete: Click this button to delete the selected condition.
- DExecute: Click this button to execute the assignment.
- DAngle field: Choose the field in the dataset which contains the angle values.
- DAngle values: Hint that angle values have to be entered in DD (not DMS).
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