Revert "docs: consolidate stored procedure scripting reference"

This reverts commit 9ba7606.

Author: BohuTANG

docs/en/guides/54-query/02-advanced/stored-procedure.md

@@ -7,7 +7,7 @@ A stored procedure is a set of executable commands or logic blocks stored within
 
 ## Supported Languages
 
-**Databend currently supports [SQL Scripting](/sql/stored-procedure-scripting/) only**. Using SQL scripting, users can define procedures with control flow constructs like loops (FOR, WHILE, REPEAT) and conditionals (IF, CASE), enabling complex logic and effective multi-step operations.
+**Databend currently supports [SQL Scripting](/sql/sql-reference/sql-scripting) only**. Using SQL scripting, users can define procedures with control flow constructs like loops (FOR, WHILE, REPEAT) and conditionals (IF, CASE), enabling complex logic and effective multi-step operations.
 
 ## Limitations
 
@@ -62,3 +62,4 @@ CALL PROCEDURE sum_even_numbers(1, 10);
 │ 30     │
 └────────┘
 ```
+

docs/en/sql-reference/00-sql-reference/42-lambda-expressions.md

@@ -0,0 +1,47 @@
+---
+title: Lambda Expressions
+---
+
+Lambda expressions are anonymous functions that allow you to encapsulate logic and pass it as an argument to higher-order functions, such as those for processing arrays, lists, or other complex data types. It typically takes a set of input parameters and a body of code that is executed for each element in a collection or for each comparison in sorting logic.
+
+## Syntax
+
+```sql
+-- Take one parameter
+<parameter> -> <expression>
+
+-- Take multiple parameters
+(<parameter1>, <parameter2>, ...) -> <expression>
+```
+
+| Parameter                         | Description                                                                                    |
+|-----------------------------------|------------------------------------------------------------------------------------------------|
+| `<parameter1>, <parameter2>, ...` | Values that the Lambda will operate on (e.g., elements of an array).                           |
+| `->`                              | Separates the input parameters from the logic.                                                 |
+| `<expression>`                    | The logic that applies to the input parameters, often written as a conditional or calculation. |
+
+## Examples
+
+This lambda expression takes a single argument n and adds 5 to it:
+
+```bash
+n -> (n + 5)
+```
+
+This lambda expression takes an integer x and returns `Positive` if x is greater than 0, otherwise it returns `Non-Positive`:
+
+```bash
+x -> (CASE WHEN x > 0 THEN 'Positive' ELSE 'Non-Positive' END)
+```
+
+This lambda expression checks if num is even. It returns `true` for even numbers and `false` for odd numbers:
+
+```bash
+num -> (num % 2 = 0)
+```
+
+This lambda expression adds the two parameters x and y:
+
+```bash
+(x, y) -> (x + y)
+```