In the last column, 'Introduction to tables,' I introduced you to tables by investigating structure, the major commands, and various properties of tables. This month's column explains how to insert captions, span rows and columns across other cells, place objects within your cells, and lay out your Web page so your tables adapt according to various screen resolutions.
A caption is simply a label that goes above or below your table for display purposes. Most of the time, you won't require captions. Tables are generally used for the layout of your Web page, and are therefore invisible to the user. However, there may be times when you wish to tabulate statistical data or the like, and may require a label for descriptive purposes.
To insert a caption in your tables, use the CAPTION command between TABLE and TR. By default, the caption will place itself on the top of your table. If you want it below the table, simply include align="bottom" in the caption command.
ROWSPAN AND COLSPAN
So far we have only looked at tables with an equal amount of cells on each row. Sometimes, however, you will have one cell that needs to span a number of others. For these occurrences, we use the ROWSPAN or COLSPAN properties within TD. It can become extremely confusing using rowspans and colspans; consequently, some people use general comments when spanning a cell.
See Figure 1 for colspan and rowspan examples.
TIP: If you are befuddled, take your tables row by row, using a ruler to hide the rest of the table. As you get to each cell you may realise that the cells above it span. At this point, go back to the appropriate TD and insert your colspan or rowspan values. Taking it row by row always makes it easier.
OBJECTS WITHIN TABLES
We have only inserted text within our table cells. It is important to realise that the wording within your TD is simply a contained object, which happens to be text. You can format this text in the same way as discussed in previous articles.
Similarly, you can insert pictures, links and lists irrespective of the fact that they are within a table cell. The code below displays more examples of TDs with valid contained objects.
<TD><img src="picture.gif"> </TD>
Notice that the fourth example is a table within a TD. Although this looks quite complicated, tables within tables are a common occurrence.
TIP: If you want a cell to have a background colour but no other data, you MUST insert a no break space as the contained object of your TD. Otherwise, Netscape will consider the cell to be empty and therefore not display it at all!
For example: <TD bgcolor="pink"> </TD>
The two common screen size resolutions used on computers are 800x600 and 1024x768 (these figures are in pixels and in format width by height). When coding your Web sites, ensure that it looks good in both these resolutions. If you hard code a table to be 1024 pixels wide (to suit the larger screen), then users with the smaller settings will have to scroll to the right to view the entire table.
To make the table change dynamically according to the individuals' settings, use percentages instead. By setting a table to width="100%", the code will stretch to the full extent of the screen width, regardless of whether that is 1024 pixels or 800 pixels.