Function (SQLite JDBC 3.8.6 API)

java.lang.Object
- org.sqlite.Function

Direct Known Subclasses:

Function.Aggregate
```
public abstract class Function
extends Object
```
Provides an interface for creating SQLite user-defined functions.
A subclass of org.sqlite.Function can be registered with Function.create() and called by the name it was given. All functions must implement xFunc(), which is called when SQLite runs the custom function.
Eg.
```
      Class.forName("org.sqlite.JDBC");
      Connection conn = DriverManager.getConnection("jdbc:sqlite:");

      Function.create(conn, "myFunc", new Function() {
          protected void xFunc() {
              System.out.println("myFunc called!");
          }
      });

      conn.createStatement().execute("select myFunc();");
  
```
Arguments passed to a custom function can be accessed using the protected functions provided. args() returns the number of arguments passed, while value_<type>(int) returns the value of the specific argument. Similarly a function can return a value using the result(<type>) function.

Aggregate functions are not yet supported, but coming soon.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Function.Aggregate
Provides an interface for creating SQLite user-defined aggregate functions.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Function.Aggregate` Provides an interface for creating SQLite user-defined aggregate functions.

Constructor Summary

Constructors
Constructor and Description

Function()

Constructors
Constructor and Description
`Function()`

Method Summary

Methods
Modifier and Type	Method and Description
`protected int`	`args()` Returns the number of arguments passed to the function.
`static void`	`create(Connection conn, String name, Function f)` Registers a given function with the connection.
`static void`	`destroy(Connection conn, String name)` Removes a named function from the given connection.
`protected void`	`error(String err)` Called by `xFunc` to throw an error.
`protected void`	`result()` Called by `xFunc` to return a value.
`protected void`	`result(byte[] value)` Called by `xFunc` to return a value.
`protected void`	`result(double value)` Called by `xFunc` to return a value.
`protected void`	`result(int value)` Called by `xFunc` to return a value.
`protected void`	`result(long value)` Called by `xFunc` to return a value.
`protected void`	`result(String value)` Called by `xFunc` to return a value.
`protected byte[]`	`value_blob(int arg)` Called by `xFunc` to access the value of an argument.
`protected int`	`value_bytes(int arg)` Called by `xFunc` to access the value of an argument.
`protected double`	`value_double(int arg)` Called by `xFunc` to access the value of an argument.
`protected int`	`value_int(int arg)` Called by `xFunc` to access the value of an argument.
`protected long`	`value_long(int arg)` Called by `xFunc` to access the value of an argument.
`protected String`	`value_text(int arg)` Called by `xFunc` to access the value of an argument.
`protected int`	`value_type(int arg)` Called by `xFunc` to access the value of an argument.
`protected abstract void`	`xFunc()` Called by SQLite as a custom function.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Function
```
public Function()
```
- Method Detail
  - create
```
public static final void create(Connection conn,
          String name,
          Function f)
                         throws SQLException
```
    Registers a given function with the connection.
    
    Parameters:
    conn - The connection.
    name - The name of the function.
    f - The function to register.
    
    Throws:
    
    SQLException
  - destroy
```
public static final void destroy(Connection conn,
           String name)
                          throws SQLException
```
    Removes a named function from the given connection.
    
    Parameters:
    conn - The connection to remove the function from.
    name - The name of the function.
    
    Throws:
    
    SQLException
  - xFunc
```
protected abstract void xFunc()
                       throws SQLException
```
    Called by SQLite as a custom function. Should access arguments through value_*(int), return results with result(*) and throw errors with error(String).
    
    Throws:
    
    SQLException
  - args
```
protected final int args()
                  throws SQLException
```
    Returns the number of arguments passed to the function. Can only be called from xFunc().
    
    Throws:
    
    SQLException
  - result
```
protected final void result(byte[] value)
                     throws SQLException
```
    Called by xFunc to return a value.
    
    Parameters:
    value -
    
    Throws:
    
    SQLException
  - result
```
protected final void result(double value)
                     throws SQLException
```
    Called by xFunc to return a value.
    
    Parameters:
    value -
    
    Throws:
    
    SQLException
  - result
```
protected final void result(int value)
                     throws SQLException
```
    Called by xFunc to return a value.
    
    Parameters:
    value -
    
    Throws:
    
    SQLException
  - result
```
protected final void result(long value)
                     throws SQLException
```
    Called by xFunc to return a value.
    
    Parameters:
    value -
    
    Throws:
    
    SQLException
  - result
```
protected final void result()
                     throws SQLException
```
    Called by xFunc to return a value.
    
    Throws:
    
    SQLException
  - result
```
protected final void result(String value)
                     throws SQLException
```
    Called by xFunc to return a value.
    
    Parameters:
    value -
    
    Throws:
    
    SQLException
  - error
```
protected final void error(String err)
                    throws SQLException
```
    Called by xFunc to throw an error.
    
    Parameters:
    err -
    
    Throws:
    
    SQLException
  - value_bytes
```
protected final int value_bytes(int arg)
                         throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException
  - value_text
```
protected final String value_text(int arg)
                           throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException
  - value_blob
```
protected final byte[] value_blob(int arg)
                           throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException
  - value_double
```
protected final double value_double(int arg)
                             throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException
  - value_int
```
protected final int value_int(int arg)
                       throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException
  - value_long
```
protected final long value_long(int arg)
                         throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException
  - value_type
```
protected final int value_type(int arg)
                        throws SQLException
```
    Called by xFunc to access the value of an argument.
    
    Parameters:
    arg -
    
    Throws:
    
    SQLException

Class Function

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Function

Method Detail

create

destroy

xFunc

args

result

result

result

result

result

result

error

value_bytes

value_text

value_blob

value_double

value_int

value_long

value_type