ACC95: Table and Query Questions and Answers (137344)

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1. Q. How can I optimize my queries?
   
   A. Microsoft Access uses Rushmore(TM), a data-access technology that permits sets of records to be queried efficiently. To optimize performance, try the following tips:
   
   
   • Run the Performance Analyzer.
   • Index the fields used in sorts and criteria.
   • Index the fields used in joins in both tables.
   • Use multiple-field indexes on fields where there are multiple-column joins between the tables.
   • If a table has a single-field primary key, do not add a separate index to the primary key field. If a table has a multiple-field primary key, add a separate index on each field.
   • Use outer joins only when necessary. Outer joins limit the options for the query optimizer.
   For more information about query performance, search on the phrase "How do I optimize my query" then view "Tell Me About: Optimizing query performance" using the Answer Wizard from the Microsoft Access Help menu. Or, see 112112.
2. Q. How can I print the Relationships window?
   
   A. Microsoft Access does not have an option to print the graphical Relationships window. However, you can press ALT+PRINTSCREEN to copy the image to the Clipboard, and then paste the image into another program, such as Paint in Microsoft Windows 95, to print it.
3. Q. All of a sudden I see tables in my database with names that start with MSys. How did they get there? Can I delete them?
   
   A. No, you definitely do not want to delete these tables. These tables are part of every .mdb file, and they keep track of the objects in your database. To hide these tables from view, follow these steps:
   
   
   1. On the Tools menu, click Options.
   2. On the View tab, click to clear the System Objects check box.
4. Q. Microsoft Access automatically joins my tables when I add them to a query. Can I turn this feature off?
   
   A. Yes, there is a new option that joins tables called AutoJoin. Use the following steps to disable the AutoJoin option:
   
   
   1. On the Tools menu, click Options.
   2. Click the Tables/Queries tab.
   3. Click the Enable AutoJoin check box to clear it.
5. Q. I like the new DisplayControl property that enables me to have a combo box in my table, but how can I have the combo box appear as a regular field when I base my query on that table?
   
   A. To change the control type back to a text box in a query, follow these steps:
   
   
   1. Open the query in Design view.
   2. Using the right mouse button, click the field in the query grid, and then click Properties on the menu that appears.
   3. Click the Lookup tab, and change the DisplayControl property to Text Box.
   Note that the DisplayControl property setting was blank before you changed it to Text Box. This property is inherited from the field's DisplayControl property in the table. Changing the property in the query grid has no effect on the property in the table.
   
   For more information about lookup fields, search on the phrase "What is a lookup field" then view "How do I create a field that looks up or lists values in tables" using the Answer Wizard from the Microsoft Access Help menu.
6. Q. What is the difference between setting the DisplayControl property on the Lookup tab to Combo Box instead of to List Box? They look the same when I view my table.
   
   A. In Datasheet view, the field or control appears as a combo box. However, when you create a form using a Wizard or when you drag fields from the field list to the form, you will see the control type specified in the field's DisplayControl property.