Revert "Revert "added procedure commands""

This reverts commit 4d6509f.

Author: soyeric128

docs/en/sql-reference/10-sql-commands/00-ddl/18-procedure/_category_.json

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+{
+  "label": "Procedure"
+}

docs/en/sql-reference/10-sql-commands/00-ddl/18-procedure/call-procedure.md

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+---
+title: CALL PROCEDURE
+---
+import FunctionDescription from '@site/src/components/FunctionDescription';
+
+<FunctionDescription description="Introduced or updated: v1.2.637"/>
+
+Executes a stored procedure by calling its name, optionally passing arguments if the procedure requires them.
+
+## Syntax
+
+```sql
+CALL PROCEDURE <procedure_name>([<argument1>, <argument2>, ...])
+```
+
+## Examples
+
+This example demonstrates how to create and call a stored procedure that converts a weight from kilograms (kg) to pounds (lb):
+
+```sql
+CREATE PROCEDURE convert_kg_to_lb(kg DECIMAL(4, 2)) 
+RETURNS DECIMAL(10, 2) 
+LANGUAGE SQL 
+COMMENT = 'Converts kilograms to pounds'
+AS $$
+BEGIN
+    RETURN kg * 2.20462;
+END;
+$$;
+
+CALL PROCEDURE convert_kg_to_lb(10.00);
+
+┌────────────┐
+│   Result   │
+├────────────┤
+│ 22.0462000 │
+└────────────┘
+```

docs/en/sql-reference/10-sql-commands/00-ddl/18-procedure/create-procedure.md

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+---
+title: CREATE PROCEDURE
+---
+import FunctionDescription from '@site/src/components/FunctionDescription';
+
+<FunctionDescription description="Introduced or updated: v1.2.637"/>
+
+Defines a stored procedure that executes SQL operations and returns a result.
+
+## Syntax
+
+```sql
+CREATE PROCEDURE <procedure_name>(<parameter_name> <data_type>, ...) 
+RETURNS <return_data_type> [NOT NULL]
+LANGUAGE <language> 
+[ COMMENT '<comment>' ] 
+AS $$
+BEGIN
+    <procedure_body>
+    RETURN <return_value>;
+END;
+$$;
+```
+
+| Parameter                               | Description                                                                                                               |
+|-----------------------------------------|---------------------------------------------------------------------------------------------------------------------------|
+| `<procedure_name>`                      | Name of the procedure.                                                                                                    |
+| `<parameter_name> <data_type>`          | Input parameters (optional), each with a specified data type. Multiple parameters can be defined and separated by commas. |
+| `RETURNS <return_data_type> [NOT NULL]` | Specifies the data type of the return value. `NOT NULL` ensures the returned value cannot be NULL.                        |
+| `LANGUAGE`                              | Specifies the language in which the procedure body is written. Currently, only `SQL` is supported.                        |
+| `COMMENT`                               | Optional text describing the procedure.                                                                                   |
+| `AS ...`                                | Encloses the procedure body, which contains SQL statements, variable declarations, loops, and a  RETURN statement.        |
+
+## Examples
+
+This example defines a stored procedure that converts weight from kilograms (kg) to pounds (lb):
+
+```sql
+CREATE PROCEDURE convert_kg_to_lb(kg DECIMAL(4, 2)) 
+RETURNS DECIMAL(10, 2) 
+LANGUAGE SQL 
+COMMENT = 'Converts kilograms to pounds'
+AS $$
+BEGIN
+    RETURN kg * 2.20462;
+END;
+$$;
+```

docs/en/sql-reference/10-sql-commands/00-ddl/18-procedure/drop-procedure.md

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+---
+title: DROP PROCEDURE
+---
+import FunctionDescription from '@site/src/components/FunctionDescription';
+
+<FunctionDescription description="Introduced or updated: v1.2.637"/>
+
+Deletes an existing stored procedure.
+
+## Syntax
+
+```sql
+DROP PROCEDURE <procedure_name>([<parameter_type1>, <parameter_type2>, ...])
+```
+
+- If a procedure has no parameters, use empty parentheses: `DROP PROCEDURE <procedure_name>()`;
+- For procedures with parameters, specify the exact types to avoid errors.
+
+## Examples
+
+This example creates and then drops a stored procedure:
+
+```sql
+CREATE PROCEDURE convert_kg_to_lb(kg DECIMAL(4, 2)) 
+RETURNS DECIMAL(10, 2) 
+LANGUAGE SQL 
+COMMENT = 'Converts kilograms to pounds'
+AS $$
+BEGIN
+    RETURN kg * 2.20462;
+END;
+$$;
+
+DROP PROCEDURE convert_kg_to_lb(Decimal(4, 2));
+```

docs/en/sql-reference/10-sql-commands/00-ddl/18-procedure/index.md

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+---
+title: Procedure
+---
+import IndexOverviewList from '@site/src/components/IndexOverviewList';
+
+This page provides reference information for the procedure-related commands in Databend.
+
+<IndexOverviewList />

docs/en/sql-reference/10-sql-commands/00-ddl/18-procedure/show-procedures.md

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+---
+title: SHOW PROCEDURES
+---
+import FunctionDescription from '@site/src/components/FunctionDescription';
+
+<FunctionDescription description="Introduced or updated: v1.2.637"/>
+
+Returns a list of all stored procedures in the system.
+
+## Syntax
+
+```sql
+SHOW PROCEDURES
+```
+
+## Examples
+
+```sql
+SHOW PROCEDURES;
+
+┌────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
+│       name       │ procedure_id │                        arguments                        │            comment           │       description      │         created_on         │
+├──────────────────┼──────────────┼─────────────────────────────────────────────────────────┼──────────────────────────────┼────────────────────────┼────────────────────────────┤
+│ convert_kg_to_lb │         2104 │ convert_kg_to_lb(Decimal(4, 2)) RETURN (Decimal(10, 2)) │ Converts kilograms to pounds │ user-defined procedure │ 2024-11-07 04:12:25.243143 │
+└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+```