San José State University
Department of Economics
Thayer Watkins
Silicon Valley
& Tornado Alley

Microsoft Access

Microsoft Access is a convenient database package. It has templates for creating personal databases for books, recipes, etc. These templates are accessed by the Database Wizard which can be opened from the initial screen. The more specialized databases are created using

It is important to note that a database file must be created at the beginning because the database tables containing the information for the database can only be stored in such database files, which have the extention .mdb. Otherwise, you may find that you enter the data in a table but because you have no .mdb file to store it in it will be lost.

It is probably most efficient to enter the data into an Excel file and then import that file into Access. One reason that it is more convenient to work through Excel is that arithmetic manipulations such as computing ratios are easily done in Excel but only done with difficulty or not at all in Access.

There is at least one feature that may make it worth the extra effort to enter the data directly into a database table in Access. Access allows one to specify the exact nature of the data for a particular variable (column) and will thus prevent the entry of data that goes beyond the allowed range. For example, suppose that some variable must be a percentage between 0 and 100. Once that condition, called a validation rule in Access, is specified then Access will refuse to accept an entry of a negative number or a number larger than 100. Also if a datum is not available then a NULL value may be entered and Access will not treat that NULL entry as a zero but will carry out operation properly taking into account that that item is missing.

Thus one should go through the process of "designing" the database. This includes specifying the nature of the variables and giving the column headings. In particular, if you do not tell Access that a column of data is numerical it will, by fault, treat it as text even though all the characters are digits. You indicate that the type of a variable is Number in the design view by clicking on the table cell that gives the type of the variable as Text. At the right of the cell a square appears with a black triangle. When you click on the black triangle a list of data type appears and you can scroll down to the entry, Number and click. That enters Number as the type of the variable.

Once the data is entered into the database the operations of sorting and selecting subtables from the data can be carried out.

Retrieving information from a database involves generally the creation of subtables.

Creation of Subtables by Means of Queries

Importing a database from Excel

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