Update index.md

Author: BohuTANG

docs/en/sql-reference/20-sql-functions/index.md

@@ -2,46 +2,51 @@
 title: SQL Function Reference
 ---
 
-These topics provide reference information for the system-defined functions.
+These topics provide reference information for the system-defined functions in Databend.
 
-## Scalar Functions
+## Data Type Functions
 
-- [Bitwise Expression Functions](./01-bitmap-functions/index.md) Perform bitwise operations and manipulations.
-- [Conditional Expression Functions](./03-conditional-functions/index.md) Implement conditional logic and case statements
-- [Context Functions](./15-context-functions/index.md) Provide information about the current SQL execution context.
-- [Conversion Functions](./02-conversion-functions/index.md) Convert data types and cast values.
-- [Date & Time Functions](./05-datetime-functions/index.md) Manipulate and format dates and times.
-- [Geospatial Functions](./09-geo-functions/index.md) Handle and manipulate geospatial data.
-- [Numeric Functions](./04-numeric-functions/index.md) Perform calculations and numeric operations.
-- [String Functions](./06-string-functions/index.md) Manipulate strings and perform regular expression operations.
-- [Semi-structured and Structured Data Functions](./10-semi-structured-functions/index.md) Work with JSON and other structured data formats.
-- [Array Functions](./00-array-functions/index.md) Handle and manipulate array data.
-- [Map Functions](10-map-functions/index.md) Handle and manipulate map data.
+- [Array Functions](./00-array-functions/index.md) - Handle and manipulate array data.
+- [Map Functions](./10-map-functions/index.md) - Handle and manipulate map data.
+- [String Functions](./06-string-functions/index.md) - Manipulate strings and perform regular expression operations.
+- [Numeric Functions](./04-numeric-functions/index.md) - Perform calculations and numeric operations.
+- [Date & Time Functions](./05-datetime-functions/index.md) - Manipulate and format dates and times.
+- [Interval Functions](./05-interval-functions/index.md) - Work with time intervals and durations.
+- [Semi-structured and Structured Data Functions](./10-semi-structured-functions/index.md) - Work with JSON and other structured data formats.
 
-## Aggregate Functions
+## Analytical Functions
 
-- [Aggregate Functions](./07-aggregate-functions/index.md) Calculate summaries like sum, average, count, etc.
-- [Window Functions](./08-window-functions/index.md) Provide aggregate calculations over a specified range of rows.
+- [Aggregate Functions](./07-aggregate-functions/index.md) - Calculate summaries like sum, average, count, etc.
+- [Window Functions](./08-window-functions/index.md) - Provide aggregate calculations over a specified range of rows.
 
-## Full-Text Search Functions
+## AI and Vector Functions
 
-- [Full-Text Search Functions](10-search-functions/index.md) Leverage inverted indexes for efficient data retrieval.
+- [AI Functions](./11-ai-functions/index.md) - Leverage AI and machine learning capabilities.
+- [Vector Distance Functions](./11-vector-distance-functions/index.md) - Calculate distances between vectors for similarity search.
 
-## AI Functions
+## Geospatial Functions
 
-- [AI Functions](./11-ai-functions/index.md) Leverage AI and machine learning capabilities.
+- [Geo Functions](./09-geo-functions/index.md) - Handle and manipulate geospatial data.
+- [Geometry Functions](./09-geometry-functions/index.md) - Work with geometric shapes and calculations.
 
-## Specialized Functions
+## Data Processing Functions
 
-- [Hash Functions](./12-hash-functions/index.md) Generate hash values for data security and comparison.
-- [IP Address Functions](./14-ip-address-functions/index.md) Manipulate and analyze IP address data.
-- [UUID Functions](./13-uuid-functions/index.md) Generate and manipulate UUIDs.
+- [Conversion Functions](./02-conversion-functions/index.md) - Convert data types and cast values.
+- [Conditional Functions](./03-conditional-functions/index.md) - Implement conditional logic and case statements.
+- [Bitmap Functions](./01-bitmap-functions/index.md) - Perform bitwise operations and manipulations.
+- [Full-Text Search Functions](./10-search-functions/index.md) - Leverage inverted indexes for efficient data retrieval.
 
-## System and Table Functions
+## System and Utility Functions
 
-- [System Functions](./16-system-functions/index.md) Access system-level information and perform control operations.
-- [Table Functions](./17-table-functions/index.md) Return results in a tabular format.
+- [System Functions](./16-system-functions/index.md) - Access system-level information and perform control operations.
+- [Table Functions](./17-table-functions/index.md) - Return results in a tabular format.
+- [Context Functions](./15-context-functions/index.md) - Provide information about the current SQL execution context.
+- [Hash Functions](./12-hash-functions/index.md) - Generate hash values for data security and comparison.
+- [UUID Functions](./13-uuid-functions/index.md) - Generate and manipulate UUIDs.
+- [IP Address Functions](./14-ip-address-functions/index.md) - Manipulate and analyze IP address data.
 
-## Other Functions
+## Other Specialized Functions
 
-- [Other Miscellaneous Functions](20-other-functions/index.md) A collection of various other functions.
+- [Dictionary Functions](./19-dictionary-functions/index.md) - Work with dictionary data structures.
+- [Sequence Functions](./18-sequence-functions/index.md) - Generate and manipulate sequences.
+- [Other Miscellaneous Functions](./20-other-functions/index.md) - A collection of various other functions.