Assign a null value to a variable.
1 null
<null
name='name'
type='type'
>
<var | expr /> ?
</null>
| Attributes | |||||
|---|---|---|---|---|---|
| Name | Type | Required | Default | Description | |
| Aname | string | Name of the variable. | |||
| Atype | string | Type of variable. | |||
| Arguments | |||||
|---|---|---|---|---|---|
| Name | Type | Required | Unique | Nullable | Description |
| Evar | expr | Entry variables of the SQL Object. | ||||
| Returns | |
|---|---|
| Type | Description |
| Null | Variable with null value. |
Exceptions
only one variable admited
Only requires a variable as argument
incorrect null type
Incorrect type.
Remarks
The attribute name and the argument var | expr are excluding.
Through the attribute name of the label <null>, the variable to which you want tot assign the null value is indicated.
Also two operators NULL are available for expressions of conditional sentences: <isnull> and <isnotnull>.
Example
Show variable with null value.
Copy
<xsql-script name='null_sample1'>
<body>
<null name='a' />
<println>
The variable 'a' contains <a/> and is of type
<variable.typeof><a/></variable.typeof>
</println>
</body>
</xsql-script>
Returns:
Copy
The variable 'a' contains null and is of type null
Example
Show variable with null value.
Copy
<xsql-script name='null_sample2'>
<body>
<set name='a'><null /></set>
<println>
The variable 'a' contains <a/> and is of type
<variable.typeof><a/></variable.typeof>
</println>
</body>
</xsql-script>
Returns:
Copy
The variable 'a' contains null and is of type null
Example
Show variable without null value.
Copy
<xsql-script name='null_sample3'>
<body>
<set name='a' type='string'>hola</set>
<println>
The variable 'a' contains <a/> and is of type
<variable.typeof><a/></variable.typeof>
</println>
</body>
</xsql-script>
Returns:
Copy
The variable 'a' contains hello and is of type java.lang.String