Show 8.2.1.16 ORDER BY Optimization This section describes when MySQL can use an index to satisfy an An
Use of Indexes to Satisfy ORDER BY In some cases, MySQL may use an index to satisfy an The index may also be used even if the Assuming that there is an index on
In some cases, MySQL cannot use indexes to resolve the
Availability of an index for sorting may be
affected by the use of column aliases. Suppose that the column
In this statement, the name of the column in the select list is also
In the following statement, the
Previously (MySQL 5.7 and lower), Use of filesort to Satisfy ORDER BY If an index cannot be used to satisfy an To obtain memory for A
Such queries are common in web applications that display only a few rows from a larger result set. Examples:
Influencing ORDER BY Optimization For slow To increase
ORDER BY Execution Plan Information Available
With
In addition, if a
The
When sorting data on more than one field in an Access query which field is the major sort key?When you are sorting records by more than one field (such as sorting by rep number and then by customer name), the first sort field (RepNum) is called the major sort key (also called the primary sort key) and the second sort field (CustomerName) is called the minor sort key (also called the secondary sort key).
How do you sort data in an Access query?On the Home tab, in the Sort & Filter group, click Advanced and then click Advanced Filter/Sort on the shortcut menu. A new document tab appears, containing a design grid and a window in which you can select a field on which to sort. In the window, double-click the field that you want to use to sort.
What does it mean to qualify a field name?To qualify a field name means to indicate the table to which it belongs by preceding the field name with the table. name and a period. To qualify the Street field in the Customer table, you would enter Customer.
In which row of the access design grid do you include functions?In which row of the Access design grid do you include functions? What functions can you use in Access queries? To use functions to perform calculations in Access, include the appropriate function in the Total row for the appropriate column of the design grid.
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