ORDER BY FORMULA
ORDER BY FORMULA ( aTable ; formula {; > or <}{; formula2 ; > or <2 ; ... ; formulaN ; > or <N} )
| Parameter | Type | Description | |
|---|---|---|---|
| aTable | Table | → | Table for which to order selected records |
| formula | Expression | → | Expression on which to set the order for each level (can be of type Alphanumeric, Real, Integer, Long Integer, Date, Time or Boolean) |
| > or < | Operator | → | Ordering direction for each level: > to order in ascending order, or < to order in descending order |
Description
ORDER BY FORMULA sorts (reorders) the records of the current selection of aTable for the current process. After the sort has been completed, the new first record of the selection becomes the current record. Note: you must specify aTable. You cannot use a default table.
You can sort the selection on one or several levels. For each sort level, you specify an expression in formula and the sorting order in > or <. If you pass the “greater than” symbol (>), the order is ascending. If you pass the “less than” symbol (<), the order is descending. If you do not specify the sorting order, ascending order is the default.
The formula parameter can be of type: Alphanumeric, Real, Integer, Long Integer, Date, Time or Boolean.
Warning: Parameters ($1...$n) are not supported in the formula.
Note: If ORDER BY FORMULA is used in conjunction with PRINT SELECTION, BREAK LEVEL and a local variable, the three commands must be executed from the same method, otherwise an error will be generated. This is because PRINT SELECTION needs to reevaluate the formula to compute break values. For example, if you execute ORDER BY FORMULA( [T1] ; [T1]f1 > $value) from a method, the sort is done and the method ends. Any subsequent call to PRINT SELECTION and BREAK LEVEL will fail because $value no longer exists and the formula cannot be evaluated.
No matter how a sort has been defined, if the actual sort operation is going to take some time to be performed, 4D automatically displays a message containing a progress indicator. These messages can be turned on and off by using the MESSAGES ON and MESSAGES OFF commands. If the progress indicator is displayed, the user can click the Stop button to interrupt the sort. If the sort is completed, OK is set to 1. Otherwise, if the sort is interrupted, OK is set to 0 (zero).
4D Server: This command is executed on the server, which optimizes its execution. Note that when variables are called directly in the formula, the sort order is calculated with the value of the variable on the client machine. For example, the statement ORDER BY FORMULA([mytable];[mytable]myfield*myvariable) will be executed on the server but with the contents of the client machine's myvariable.
Compatibility note: Until 4D Server v11, this command was executed on the client machine. For reverse compatibility, this behavior is maintained in converted databases. However, a compatibility property or a selector of the SET DATABASE PARAMETER command enables server-side execution in converted databases.
Example
This example orders the records of the [People] table in descending order, based on the length of each person’s last name. The record for the person with the longest last name will be first in the current selection:
ORDER BY FORMULA([People];Length([People]Last Name);<)
See also
Properties
| Command number | 300 |
| Thread safe | ✓ |
| Modifies variables | OK |
| Changes current record |