Select query
Select query is the most commonly used query method, which can be used not only for multi-condition combination query, but also for user-defined query, statistical query of "sum value" and "mean value", and sorting the results if necessary.
Cross-table query
Cross-table query usually takes one field as the row header of the table and the value of another field as the column header to obtain the summary information of the data at the cell where the row and column intersect, so as to achieve the purpose of data statistics. Crosstab queries can be created through the Crosstab Query Wizard or in design view.
Parameter query
Parameter query is a dynamic query. You can enter different criteria values each time you run the query. The system determines the query result according to the given parameter value, but it is not necessary to define the parameter value when creating the query. This kind of query is completely controlled by users, which can adapt to the changing needs of applications to a certain extent and improve the query efficiency. Parameter queries are generally created on the basis of select queries. When you run a query, one or more dialog boxes will appear asking about the query conditions. Because of the randomness of parameters, the query results have great flexibility, so they often become the data basis of forms, reports and other objects.
According to the different number of parameters in the query, parameter query can be divided into single parameter query and multi-parameter query.
Operation query
Operation query is used to perform global data management operations on one or more tables at the same time. Operation query can edit the original data content in the data table and modify the qualified data in batches. Therefore, the database should be backed up when making operation query.
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