QUERY PRACTICE
Queries are used to question and obtain information from databases.
When you want to ask for ranges or specific ranges you use queries.
Criteria are restrictions you place on a query or filter to identify the specific records you want to work with. For example, instead of viewing all the suppliers that your company uses, you can view just suppliers from Japan. To do this, you specify criteria that limits the results to records whose Country field is "Japan." To specify criteria for a field in the design grid, enter an expression in the Criteria cell for that field. The expression in the preceding example would be "Japan." You can use more complicated expressions, however, such as "Between 1000 And 5000."
You can enter additional criteria for the same field or different fields. When you type expressions in more than one Criteria cell, Microsoft Access combines them using either the And or the Or operator. If the expressions are in different cells in the same row, Microsoft Access uses the And operator. If the expressions are in different rows of the design grid, Microsoft Access uses the Or operator.
You can also specify criteria to affect the results of a calculation. By adding criteria, you can limit the groups for which you're performing a calculation, limit the records included in the calculation, or limit the results that are displayed after the calculation is performed. For examples of how to use multiple criteria in the design grid, click .
Logical expressions
AND: Means both conditions must be met
OR: Means either conditions must be met
NOT: Means anything but this condition
TYPES OF QUERIES
SELECT QUERIES: Select queries provide results based on your questions. For example, you may use a select query to see how many employees have been with the company for five years
ACTION QUERIES: Action queries add to or update existing data. For example, you may increase the contents of the salary field for each employee found above by a certain percentage
This page created by David Lewis 7/3/97