The dba Library Tags

Here's a listing of all Tags in the dba Tag Library. It should serve as a ready reference for Syntax, as well as a description on how to use each Tag.

However, you should not attempt to read this section without first obtaining a thorough understanding of the overall theory of operation behind the dba Library. You do that by reading the two previous sections, namely The dba Library and dba Special Topics. This Library is sure to become the foundation for your most frequently used Tags and we've gone to great pains to make sure you have adequate documentation to help you get the most from this Library.

If you feel you're ready, then go ahead. We're sure you'll be writing great database applications in no time.

< dbapp *app, rel, src, maint=false />

This Tag defines a dba Application and is therefore the starting point. All data concerning a particular application is stored in the output variable app. All other dba Tags need this value for their input.

rel is the name of the database relation to be worked on.

src is the name of the heitml page which does the processing. This is usually the page itself.

In maintenance mode database relations can be created and dropped simply by calling the page from your Web Browser.

< dbacreate app> ... </dbacreate>

Inside the <dbacreate> environment Tag you can specify SQL statements to create the database relation needed. These statements are executed only if the page is called with parameter action=create (and maintenance mode is on - See the <dbapp> Tag above for further information on maintenance mode).

The page can also be called with action=drop to drop the table or with action=drcreate to drop and re-create the tables. This mechanism provides a convenient way to create database tables as needed, and to retain the data definition as part of the application page for documentation purposes. However, it is not necessary to use this feature since there are other ways in which the necessary database tables can be created.

< dbakeyfield app fn order="asc" />

This tag is used to define the key of the database relation to be worked on. The key can consist of one or more fields, which must be given here. Also, the most significant field must be stated first, with all other keys in their proper relative order.

app denotes the application.

fn gives the field name; it must denote the name of one attribute of the relation given.

The order parameter can be asc or desc, which gives the sort order with respect to this key field, either ascending or descending.

< dbaReadRecord app *r key=ff.k> ... </dbaReadRecord>

Reads the designated record and makes it accessible through r. Normally <dbaReadRecord> is not necessary, but it is useful for special applications.

< dbaupdate app *r *o submitaction=null action=dbaupdateaction(app) key=default(ff.k) rec=default(ff.r)> ... </dbaupdate>

Performs the requested actions to the database, either insert a record or update it. The environment checks should be placed within to check the User input for correctness and consistency. The original record is accessible through o and the entered record through r. o==null indicates that an insert is about to take place.

If there is an error detected, <dbaErrMsg>, <dbaFehler>, or <dbaRedisplay> can be called. Then the insert or update is not performed, but instead ff.redisplay is set to make a subsequent <dbaForm> show the user input in redisplay mode.

submitaction gives the action to be done by a subsequent <dbaForm> if the insert or update was successful. Usual values are show or display.

< dbaDelete app *r deleteaction=null action=dbaupdateaction(app) key=default(ff.k)>> ... </dbaDelete>

Performs a delete on the database if requested. Inside the environment it can be checked whether a delete is possible and allowed. If there is an error detected then <dbaErrMsg>, <dbaFehler>, or <dbaRedisplay> can be called. Then the delete is not performed but instead ff.redisplay is set to make a subsequent <dbaForm> show the user input in redisplay mode.

DeleteAction gives the action that is to be performed after the delete was successful. Useful are "no" to do nothing or "showemp" to show an empty FORM.

< dbaKeyUpdate />

If updating of key fields is allowed then it is necessary to call this tag just after the update. It fixes ff.k and makes it designate the record with the changed key.

< dbafi fn size=10 maxsize=size def=null />

This tag displays a text field in TABLE or FORM view.

fn must be the field name.

size is the field size when shown as a FORM field.

MaxSize is the maximum number of characters the user may enter into the field. This can be bigger than size and is handled by having the browser scroll the window.

def is a default value which is used in display mode if the field is empty. def may contain HTML Tags (e.g. def="&nbsp;" is a common usage to show empty table fields.

dbafi can be used to show key fields. All other field display Tags can not be used to show key fields.

< dbaMailto fn size=10 maxsize=size def=null> />

Works like <dbafi> and the parameters have the same meaning. However, in display mode the field content is shown and is made a mailto: hot-link.

< dbaLink fn size=10 maxsize=size def=null />

Works like <dbafi> and the parameters have the same meaning. However, in display mode the field content is shown and is made a hot link.

< dbaTextArea app fn rows=10 cols=60 wrap="physical" disp="pre" />

fn will be displayed as a text area. fn is the field name.

rows, cols, and wrap are the formatting parameters of the textarea as defined in HTML.

disp can be pre or html and specifies how the text should be shown in display mode, either as preformatted text or as HTML.

< dbaCheckBox app fn trueval="T" falseval="" />

The database field must have only two valid values given by trueval and falseval. In FORM mode the content of the environment is shown followed by a checkbox. This checkbox is checked if and only if the field fn contains the trueval. When the FORM is entered the field gets either the trueval or the falseval, depending on whether the user checked the box or not.

In display mode the content of the environment is shown only if the field fn contains the trueval.

< dbaSelect app fn />

Shows the field content in a selectable option menu of the browser. The environment must contain a list of <dbaOption> or <dbaOptionV> Tags. It is assumed that the database field contains one of the values given in an Option Tag. This option is shown selected in FORM mode. In display mode the corresponding option text is shown.

< dbaOption app value />

Defines an option of a <dbaSelect>. <dbaOption> can be used only within a <dbaSelect>.

value gives the value of the option as stored in the database. Inside the <dbaOption> environment the value to be shown to the user can be specified.

< dbaOptionV app value />

Works as a <dbaOption> environment containing the value. It can be used if the value of an option is the same in the database and on the screen.

< dbatab app fn size maxsize=size />

Is a <dbafi> enclosed in HTML <TableData> markers "<td> and </td>".

< dbatfi app fn size maxsize=size />

Must be used within an HTML TABLE. It creates two columns, the first column contains the field name and the second column a <dbafi> to show the field content.

< dbaform app *r keyact="no" action=dbashowaction(app) key=default(ff.k) rec=default(ff.r)> ... </dbaform>

Is the main dba FORM environment. Inside the environment a layout showing one database record must be specified.

< dbaAshow app key=default(app.key)> ... </dbaAshow>

Creates an HTML-link to show the current record (or the one specified by key) in a form. Content of the environment is the text which should be shown as the link.

<dbaAshow> can be used in both TABLE and FORM view.

< dbaAshowemp app key=default(app.key)> ... </dbaAshowemp>

Creates an HTML-link to show the current record (or the one specified by key) in a FORM. Content of the environment is the text which should be shown as the link.

<dbaAshowemp> can be used in both TABLE and FORM view. In case the record does not exist (any more) an empty form is shown.

< dbaAdisplay app key=default(app.key)> ... </dbaAdisplay>

Creates an HTML-link to display the current record (or the one specified by key). Content of the environment is the text which should be shown as the link.

<dbaAdisplay> can be used in both TABLE and FORM view.

< dbaAdelete app key=default(app.key)> ... </dbaAdelete>

Creates an HTML-link to delete the current record (or the one specified by key). Content of the environment is the text which should be shown as the link.

<dbaAdelete> can be used in both TABLE and FORM view. It works only if no password is required for the delete.

< dbaAPdelete app key=default(app.key)> ... </dbaAPdelete>

Creates an HTML FORM button to delete the current record (or the one specified by key). Content of the environment is the text which should be shown as the link. It may only be a string and can not contain HTML Tags.

<dbaAPdelete> can be used in FORM view and in a delete FORM Tag (e.g. <dbaPDeleteForm>).

< dbaAPDeleteForm app key=default(app.key)> ... </dbaAPDeleteForm>

Creates a delete FORM, i.e. a FORM containing a delete button and a password field.

Inside the environment a <dbaAPdelete> and a <dbafipassword> must be contained.

< dbaAsubmit > ... </dbaAsubmit>

Creates an HTML FORM button to submit the current record. Content of the environment is the text which should be shown on the button. It can only be a string and can not contain HTML Tags.

<dbaSubmit> can be used in the <dbaForm> environment.

< dbaAreset > ... </dbaAreset>

Creates an HTML FORM button to reset the <dbaForm>. Content of the environment is the text which should be shown on the button. It can only be a string and can not contain HTML Tags.

<dbaAreset> can be used in the <dbaForm> environment.

< dbaAfirst app> ... </dbaAfirst>

Creates an HTML-link to scroll to the beginning of the TABLE view. Content of the environment is the text which should be shown as the link.

<dbaAfirst> can be used anywhere.

< dbaAlast app> ... </dbaAlast>

Creates an HTML-link to scroll to the end of the TABLE view. Content of the environment is the text which should be shown as the link.

<dbaAlast> can be used anywhere

< dbaAnext app key=default(app.key)> ... </dbaAnext>

Creates an HTML-link to scroll down one page in the TABLE view. Content of the environment is the text which should be shown as the link. dbaAnext can be used in the list view.

< dbaAprev app key=default(app.startkey)> ... </dbaAprev>

Creates am HTML-link to scroll up one page in the TABLE view. Content of the environment is the text which should be shown as the link.

<dbaAprev> can be used in the TABLE view.

< dbaAempty app> ... </dbaAempty>

Creates an HTML-link to show an empty <dbaForm>. Content of the environment is the text which should be shown as the link.

<dbaAempty> can be used anywhere.

< dbaTable cnt=10 action=dbalistaction(app) key=default(ff.k) ofs=integer(default(ff.ofs,0)) cond=""> ... </dbaTable>

Main environment for the TABLE view.

Inside the environment the layout of the TABLE needs to be defined. Most prominently it should contain the <dbaTableEntry> environment to define the layout of a record in the TABLE.

The cnt parameter specifies the number of records which should be shown per page.

cond specifies a condition for which all records to be shown must fulfill. The cond string is actually appended to the SQL queries performed.

< dbaTableEntry app *r> ... </dbaTableEntry>

Environment to define the layout of a TABLE entry.

r is assigned a tuple containing the current record. Inside the environment all the dba field display Tags can be used.

< dbafipassword fn size=10 pref=" Password: " />

The <dbafipassword> Tag displays a password field.

fn is the field name.

As in the database, size is the size of the field on screen and pref is an arbitrary string to be displayed before the password.

In display mode nothing is displayed; not even the prefix.

< dbapasswordcheck app master="*" />

This Tag can be put into <dbaUpdate> and <dbaDelete> for password protection of single records. To use this functionality every record needs to have a field named password. With a new entry into the database the password is stored in the database. For update and delete the same password has to be supplied, otherwise <dbapasswordcheck> issues an error message and so prevents the update or delete from happening.