SubForms are special data-Forms because they're linked to a parent data-Form by one or more fields in common. These options (Table, Query, or SQL command) allow us to build powerful Forms incorporating information across multiple Tables, for the purposes of data-entry and/or retrieval. The latter two options (Query and SQL-command) are identical, except that 'SQL-commands' are queries stored within the Form document itself, which allows export as a self-contained, standalone Writer Form. Each data-Form is based on its own Table, Query, or SQL command. Even many-to-many relationships ( n:m) are implemented as multiple 1:n relationships combined through an intermediate ' junction table.' We can also extend/split a Table in special circumstances using a one-to-one (1:1) relationship, such as to minimize redundancy with subclasses, or to maintain performance when storing large files inside a database ( such as photos, eBooks, etc).īase Forms are optimized for data relationships using a hidden structure of MainForms & SubForms, collectively known as ' data-Forms.” This sub-structure is revealed in tree-view by selecting: View > Toolbars > Form Desi gn > Form Navigator ( see image). Such relationships serve as the backbone of a relational database. Since one client from the 'Clients' table can have many visits recorded in the 'Dates' table, we have what's known as a one-to-many relationship ( 1:n). Upon recording the visit, a linked SubForm will display the client's visit-history by date (in reverse-sort order latest visit shown first). A date-field with drop-down calendar will be used to select the visit date, while defaulting to the current date if left blank. A List Box will allow client-selection by name from the 'Clients' table while storing the client-ID to the 'Dates' table. This dedicated 'Dates' table will be used to record the client-ID and date of each visit. Overview:Īssuming a 'Clients' (contact information) table, we'll need another table to record the client-visits by date. Alisona5 ying to create a database for our local food pantry.We need to be able to search for the ntinually add dates of service for the same person.and.

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