Testing Variable Values with the [ ] Operators

You can use square brackets [ ] to test for the existence or value of a variable.

You can use square brackets to

Include optional strings and variables, or lists of strings and variables in the syntax of SQL statements: [%variable%]
Test the value of a variable and insert or reconsider a value depending of the result of the test: [%variable%? true : false]
Test the content of a variable [%variable%=constant? true : false]

Variable	Generation
`[%variable%]`	Tests for the existence of the variable. Generation: Generated only if `variable` exists and is not assigned `NO` or `FALSE`. Reverse: Evaluated if the parser detects a SQL statement corresponding to the variable and it is not assigned `NO` or `FALSE`.
`[%variable%? true : false]`	Tests for the existence of the variable and allows conditional output. Generation: `true` is generated if `variable` exists and is not assigned `NO` or `FALSE`. Otherwise, `false` is generated. Reverse: If the parser detects `variable` and it is not assigned `NO` or `FALSE`, `true` is reversed. Otherwise, `false` is reversed. `variable` is set to `True` or `False` as appropriate.
`[%variable%=constant? true : false]`	Tests the value of the variable and allows conditional output. Generation: If `variable` equals `constant`, `true` is generated. Otherwise, `false` is generated. Reverse: If the parser detects that`variable` equals `constant`, `true` is reversed. Otherwise, `false` is reversed.
`[.Z: [item1][item2]...]`	Specifies that the `items` do not have a significant order. Generation: `.Z` is ignored Reverse: The `items` can be reversed in any order they are encountered.
`[.O: [item1][item2]...]`	Specifies that the `items` are synonyms, only one of which should be output. Generation: Only the first `item` listed is generated. Reverse: The reverse parser must find one of the `items` to validate the full statement.

Examples

```
[%OPTIONS%]
```
If %OPTIONS% (physical options for the objects visible in the object property sheet) exists and is not assigned NO or FALSE, it is generated to the value of %OPTIONS%.
```
[default %DEFAULT%]
```
If the statement default 10 is found during reverse engineering, %DEFAULT% is assigned the value 10, but the statement is not mandatory and reversing continues even if it is absent. In script generation, if %DEFAULT% has a value of 10, it is generated as default 10 otherwise nothing is generated for the block.
```
[%MAND%? not null : null ]
```
If %MAND% is evaluated as true or contains a value other than False or NO, it is generated as not null. Otherwise it is generated as null.
```
[%DELCONST%=RESTRICT?:[on delete %DELCONST%]]
```
If %DELCONST% contains the value RESTRICT, it is generated as on delete RESTRICT.
```
%COLUMN% %DATATYPE%[.Z: [%NOTNULL%][%DEFAULT%]]
```
Because of the presence of the .Z variable, both of the following statements will be reversed correctly even though the column attributes are not in the same order:
- Create table abc (a integer not null default 99)
- Create table abc (a integer default 99 not null)
```
[.O:[procedure][proc]]
```
This statement will generate procedure. During reverse engineering, the parser will match either procedure or proc keywords.
Note: A string between square brackets is always generated. For reverse engineering, placing a string between square brackets means that it is optional and its absence will not cancel the reversing of the statement.
```
create [or replace] view %VIEW% as %SQL%
```
A script containing either create or create or replace will be correctly reversed because or replace is optional.