udf: add UDTF and improve the org of UDF

docs/en/sql-reference/10-sql-commands/00-ddl/10-udf/ddl-alter-function.md

@@ -1,27 +1,98 @@
 ---
 title: ALTER FUNCTION
-sidebar_position: 2
+sidebar_position: 3
 ---
 import FunctionDescription from '@site/src/components/FunctionDescription';
 
 <FunctionDescription description="Introduced or updated: v1.2.116"/>
 
-Alters a user-defined function.
+Alters a user-defined function. Supports all function types: Scalar SQL, Tabular SQL, and Embedded functions.
 
 ## Syntax
 
+### For Scalar SQL Functions
 ```sql
-ALTER FUNCTION [ IF NOT EXISTS ] <function_name> 
-    AS (<input_param_names>) -> <lambda_expression> 
+ALTER FUNCTION [ IF EXISTS ] <function_name> 
+    ( [<parameter_list>] ) 
+    RETURNS <return_type>
+    AS $$ <expression> $$
+    [ DESC='<description>' ]
+```
+
+### For Tabular SQL Functions
+```sql
+ALTER FUNCTION [ IF EXISTS ] <function_name> 
+    ( [<parameter_list>] ) 
+    RETURNS TABLE ( <column_definition_list> ) 
+    AS $$ <sql_statement> $$
+    [ DESC='<description>' ]
+```
+
+### For Embedded Functions
+```sql
+ALTER FUNCTION [ IF EXISTS ] <function_name> 
+    ( [<parameter_list>] ) 
+    RETURNS <return_type>
+    LANGUAGE <language>
+    [IMPORTS = ('<import_path>', ...)]
+    [PACKAGES = ('<package_path>', ...)]
+    HANDLER = '<handler_name>'
+    AS $$ <function_code> $$
     [ DESC='<description>' ]
 ```
 
 ## Examples
 
+### Altering Scalar SQL Function
+```sql
+-- Create a scalar function
+CREATE FUNCTION calculate_tax(income DECIMAL)
+RETURNS DECIMAL
+AS $$ income * 0.2 $$;
+
+-- Modify the function to use progressive tax rate
+ALTER FUNCTION calculate_tax(income DECIMAL)
+RETURNS DECIMAL
+AS $$ 
+  CASE 
+    WHEN income <= 50000 THEN income * 0.15
+    ELSE income * 0.25
+  END
+$$;
+```
+
+### Altering Tabular SQL Function
+```sql
+-- Create a table function
+CREATE FUNCTION get_employees() 
+RETURNS TABLE (id INT, name VARCHAR(100)) 
+AS $$ SELECT id, name FROM employees $$;
+
+-- Modify to include department and salary
+ALTER FUNCTION get_employees() 
+RETURNS TABLE (id INT, name VARCHAR(100), department VARCHAR(100), salary DECIMAL)
+AS $$ SELECT id, name, department, salary FROM employees $$;
+```
+
+### Altering Embedded Function
 ```sql
--- Create a UDF
-CREATE FUNCTION a_plus_3 AS (a) -> a+3+3;
+-- Create a Python function
+CREATE FUNCTION simple_calc(x INT)
+RETURNS INT
+LANGUAGE python
+HANDLER = 'calc'
+AS $$
+def calc(x):
+    return x * 2
+$$;
 
--- Modify the lambda expression of the UDF
-ALTER FUNCTION a_plus_3 AS (a) -> a+3;
+-- Modify to use a different calculation
+ALTER FUNCTION simple_calc(x INT)
+RETURNS INT
+LANGUAGE python
+HANDLER = 'calc'
+AS $$
+def calc(x):
+    return x * 3 + 1
+$$;
 ```

docs/en/sql-reference/10-sql-commands/00-ddl/10-udf/ddl-create-function-embedded.md

@@ -0,0 +1,211 @@
+---
+title: CREATE EMBEDDED FUNCTION
+sidebar_position: 2
+---
+import FunctionDescription from '@site/src/components/FunctionDescription';
+
+<FunctionDescription description="Introduced or updated: v1.2.339"/>
+
+Creates an Embedded UDF using programming languages (Python, JavaScript, WASM). Uses the same unified `$$` syntax as SQL functions for consistency.
+
+## Syntax
+
+```sql
+CREATE [ OR REPLACE ] FUNCTION [ IF NOT EXISTS ] <function_name> 
+    ( [<parameter_list>] ) 
+    RETURNS <return_type>
+    LANGUAGE <language>
+    [IMPORTS = ('<import_path>', ...)]
+    [PACKAGES = ('<package_path>', ...)]
+    HANDLER = '<handler_name>'
+    AS $$ <function_code> $$
+    [ DESC='<description>' ]
+```
+
+Where:
+- `<parameter_list>`: Comma-separated list of parameters with their types (e.g., `x INT, name VARCHAR`)
+- `<return_type>`: The data type of the function's return value
+- `<language>`: Programming language (`python`, `javascript`, `wasm`)
+- `<import_path>`: Stage files to import (e.g., `@s_udf/your_file.zip`)
+- `<package_path>`: Packages to install from pypi (Python only)
+- `<handler_name>`: Name of the function in the code to call
+- `<function_code>`: The implementation code in the specified language
+
+## Supported Languages
+
+| Language | Description | Enterprise Required | Package Support |
+|----------|-------------|-------------------|-----------------|
+| `python` | Python 3 with standard library | Yes | PyPI packages via PACKAGES |
+| `javascript` | Modern JavaScript (ES6+) | No | No |
+| `wasm` | WebAssembly (Rust compiled) | No | No |
+
+## Data Type Mappings
+
+### Python
+| Databend Type | Python Type |
+|--------------|-------------|
+| NULL | None |
+| BOOLEAN | bool |
+| INT | int |
+| FLOAT/DOUBLE | float |
+| DECIMAL | decimal.Decimal |
+| VARCHAR | str |
+| BINARY | bytes |
+| LIST | list |
+| MAP | dict |
+| STRUCT | object |
+| JSON | dict/list |
+
+### JavaScript
+| Databend Type | JavaScript Type |
+|--------------|----------------|
+| NULL | null |
+| BOOLEAN | Boolean |
+| INT | Number |
+| FLOAT/DOUBLE | Number |
+| DECIMAL | BigDecimal |
+| VARCHAR | String |
+| BINARY | Uint8Array |
+| DATE/TIMESTAMP | Date |
+| ARRAY | Array |
+| MAP | Object |
+| STRUCT | Object |
+| JSON | Object/Array |
+
+## Access Control Requirements
+
+| Privilege | Object Type   | Description    |
+|:----------|:--------------|:---------------|
+| SUPER     | Global, Table | Operates a UDF |
+
+To create an embedded function, the user performing the operation or the [current_role](/guides/security/access-control/roles) must have the SUPER [privilege](/guides/security/access-control/privileges).
+
+## Examples
+
+### Python Function
+
+```sql
+-- Simple Python function
+CREATE FUNCTION calculate_age_py(VARCHAR)
+RETURNS INT
+LANGUAGE python HANDLER = 'calculate_age'
+AS $$
+from datetime import datetime
+
+def calculate_age(birth_date_str):
+    birth_date = datetime.strptime(birth_date_str, '%Y-%m-%d')
+    today = datetime.now()
+    age = today.year - birth_date.year
+    if (today.month, today.day) < (birth_date.month, birth_date.day):
+        age -= 1
+    return age
+$$;
+
+-- Use the function
+SELECT calculate_age_py('1990-05-15') AS age;
+```
+
+### JavaScript Function
+
+```sql
+-- JavaScript function for age calculation
+CREATE FUNCTION calculate_age_js(VARCHAR)
+RETURNS INT
+LANGUAGE javascript HANDLER = 'calculateAge'
+AS $$
+export function calculateAge(birthDateStr) {
+    const birthDate = new Date(birthDateStr);
+    const today = new Date();
+
+    let age = today.getFullYear() - birthDate.getFullYear();
+    const monthDiff = today.getMonth() - birthDate.getMonth();
+
+    if (monthDiff < 0 || (monthDiff === 0 && today.getDate() < birthDate.getDate())) {
+        age--;
+    }
+
+    return age;
+}
+$$;
+
+-- Use the function
+SELECT calculate_age_js('1990-05-15') AS age;
+```
+
+### Python Function with Packages
+
+```sql
+CREATE FUNCTION ml_model_score()
+RETURNS FLOAT
+LANGUAGE python IMPORTS = ('@s1/model.zip') PACKAGES = ('scikit-learn') HANDLER = 'model_score'
+AS $$
+from sklearn.datasets import load_iris
+from sklearn.model_selection import train_test_split
+from sklearn.ensemble import RandomForestClassifier
+
+def model_score():
+    X, y = load_iris(return_X_y=True)
+    X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.25, random_state=42)
+
+    model = RandomForestClassifier()
+    model.fit(X_train, y_train)
+    return model.score(X_test, y_test)
+$$;
+
+-- Use the function
+SELECT ml_model_score() AS accuracy;
+```
+
+### WASM Function
+
+First, create a Rust project and compile to WASM:
+
+```toml
+# Cargo.toml
+[package]
+name = "arrow-udf-example"
+version = "0.1.0"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+arrow-udf = "0.8"
+```
+
+```rust
+// src/lib.rs
+use arrow_udf::function;
+
+#[function("fib(int) -> int")]
+fn fib(n: i32) -> i32 {
+    let (mut a, mut b) = (0, 1);
+    for _ in 0..n {
+        let c = a + b;
+        a = b;
+        b = c;
+    }
+    a
+}
+```
+
+Build and deploy:
+
+```bash
+cargo build --release --target wasm32-wasip1
+# Upload to stage
+CREATE STAGE s_udf;
+PUT fs:///target/wasm32-wasip1/release/arrow_udf_example.wasm @s_udf/;
+```
+
+```sql
+-- Create WASM function
+CREATE FUNCTION fib_wasm(INT)
+RETURNS INT
+LANGUAGE wasm HANDLER = 'fib'
+AS $$@s_udf/arrow_udf_example.wasm$$;
+
+-- Use the function
+SELECT fib_wasm(10) AS fibonacci_result;
+```
+

docs/en/sql-reference/10-sql-commands/00-ddl/10-udf/ddl-create-function.md

@@ -1,21 +1,28 @@
 ---
-title: CREATE FUNCTION
-sidebar_position: 1
+title: CREATE SCALAR FUNCTION
+sidebar_position: 0
 ---
 import FunctionDescription from '@site/src/components/FunctionDescription';
 
-<FunctionDescription description="Introduced or updated: v1.2.339"/>
+<FunctionDescription description="Introduced or updated: v1.2.799"/>
 
-Creates a user-defined function.
+Creates a Scalar SQL UDF using Databend's unified function syntax.
 
 ## Syntax
 
 ```sql
 CREATE [ OR REPLACE ] FUNCTION [ IF NOT EXISTS ] <function_name> 
-    AS ( <input_param_names> ) -> <lambda_expression> 
+    ( [<parameter_list>] ) 
+    RETURNS <return_type>
+    AS $$ <expression> $$
     [ DESC='<description>' ]
 ```
 
+Where:
+- `<parameter_list>`: Optional comma-separated list of parameters with their types (e.g., `x INT, y FLOAT`)
+- `<return_type>`: The data type of the function's return value
+- `<expression>`: SQL expression that defines the function logic
+
 ## Access control requirements
 
 | Privilege | Object Type   | Description    |
@@ -26,4 +33,31 @@ To create a user-defined function, the user performing the operation or the [cur
 
 ## Examples
 
-See [Usage Examples](/guides/query/udf#usage-examples).
+```sql
+-- Create a function to calculate area of a circle
+CREATE FUNCTION area_of_circle(radius FLOAT)
+RETURNS FLOAT
+AS $$
+  pi() * radius * radius
+$$;
+
+-- Create a function to calculate age in years
+CREATE FUNCTION calculate_age(birth_date DATE)
+RETURNS INT
+AS $$
+  date_diff('year', birth_date, now())
+$$;
+
+-- Create a function with multiple parameters
+CREATE FUNCTION calculate_bmi(weight_kg FLOAT, height_m FLOAT)
+RETURNS FLOAT
+AS $$
+  weight_kg / (height_m * height_m)
+$$;
+
+-- Use the functions
+SELECT area_of_circle(5.0) AS circle_area;
+SELECT calculate_age('1990-05-15') AS age;
+SELECT calculate_bmi(70.0, 1.75) AS bmi;
+```
+