Hi Aimen Younus,
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Usually portals work with matching text identification.
This is not really the case. Portals function first on the basis of a defined relationship in Manage | Database | Relationships. Then, if the developer chooses, they can specify an additional portal "filter" that further limits what records appear in the portal.
You could place a different portal on each tab panel of you tabl control. Each portal can be based on the same relationship but use a different portal filter to limit the related records to those meeting the filter. In you case, I would guess that on the tab for "A" you want to limit the records to those starting with A and the tab for B would limit the records to those starting with B and so forth.
You could also set up a single portal with a field that is one of the match fields in the relationship and get different sets of records depending on what value (such as a letter of the alphabet) is selected. This could be much less work than the large number of tab panels needed for different starting letters and if you used a check box format, you could even include records starting with more than one letter by selecting more than one check box.
Many of the details, however, will depend on the exact design of your tables and the data that you store in it.