Replace sqlgram links (#17468)

TOC-tidb-cloud.md

@@ -350,6 +350,7 @@
       - [Expression Syntax](/expression-syntax.md)
       - [Comment Syntax](/comment-syntax.md)
     - SQL Statements
+      - [Overview](/sql-statements/sql-statement-overview.md)
       - [`ADD COLUMN`](/sql-statements/sql-statement-add-column.md)
       - [`ADD INDEX`](/sql-statements/sql-statement-add-index.md)
       - [`ADMIN`](/sql-statements/sql-statement-admin.md)

TOC.md

@@ -721,6 +721,7 @@
       - [Expression Syntax](/expression-syntax.md)
       - [Comment Syntax](/comment-syntax.md)
     - SQL Statements
+      - [Overview](/sql-statements/sql-statement-overview.md)
       - [`ADD COLUMN`](/sql-statements/sql-statement-add-column.md)
       - [`ADD INDEX`](/sql-statements/sql-statement-add-index.md)
       - [`ADMIN`](/sql-statements/sql-statement-admin.md)

basic-sql-operations.md

@@ -13,7 +13,7 @@ To experiment with SQL and test out TiDB compatibility with MySQL queries, you c
 
 </CustomContent>
 
-This page walks you through the basic TiDB SQL statements such as DDL, DML and CRUD operations. For a complete list of TiDB statements, see [TiDB SQL Syntax Diagram](https://pingcap.github.io/sqlgram/).
+This page walks you through the basic TiDB SQL statements such as DDL, DML and CRUD operations. For a complete list of TiDB statements, see [TiDB SQL Syntax](/sql-statements/sql-statement-overview.md)).
 
 ## Category
 

develop/dev-guide-create-table.md

@@ -183,7 +183,7 @@ CREATE TABLE `bookshop`.`ratings` (
 );
 ```
 
-In addition, if the current time is also filled in by default when the data is being updated, the following statements can be used (but only the [current time related statements](https://pingcap.github.io/sqlgram/#NowSymOptionFraction) can be filled in after `ON UPDATE`, and [more options](https://pingcap.github.io/sqlgram/#DefaultValueExpr) are supported after `DEFAULT`):
+In addition, if the current time is also filled in by default when the data is being updated, the following statements can be used (but only the current-time related expressions can be filled in after `ON UPDATE`):
 
 ```sql
 CREATE TABLE `bookshop`.`ratings` (
@@ -195,6 +195,8 @@ CREATE TABLE `bookshop`.`ratings` (
 );
 ```
 
+For more information on default values of different data types, see [default values](/data-type-default-values.md).
+
 ### Prevent duplicate values
 
 If you need to prevent duplicate values in a column, you can use the `UNIQUE` constraint.

develop/dev-guide-tidb-crud-sql.md

@@ -21,7 +21,7 @@ TiDB is compatible with MySQL, you can use MySQL statements directly in most cas
 
 To experiment with SQL and test out TiDB compatibility with MySQL queries, you can try [TiDB Playground](https://play.tidbcloud.com/?utm_source=docs&utm_medium=basic-sql-operations). You can also first deploy a TiDB cluster and then run SQL statements in it.
 
-This page walks you through the basic TiDB SQL statements such as DDL, DML, and CRUD operations. For a complete list of TiDB statements, see [TiDB SQL Syntax Diagram](https://pingcap.github.io/sqlgram/).
+This page walks you through the basic TiDB SQL statements such as DDL, DML, and CRUD operations. For a complete list of TiDB statements, see [SQL Statement Overview](/sql-statements/sql-statement-overview.md).
 
 ## Category
 
@@ -35,7 +35,7 @@ SQL is divided into the following 4 types according to their functions:
 
 - **DCL (Data Control Language)**: It is used to define access privileges and security levels.
 
-The following mainly introduces DML and DQL. For more information about DDL and DCL, see [Explore SQL with TiDB](/basic-sql-operations.md) or [TiDB SQL syntax detailed explanation](https://pingcap.github.io/sqlgram/).
+The following mainly introduces DML and DQL. For more information about DDL and DCL, see [Explore SQL with TiDB](/basic-sql-operations.md) or [SQL Statement Overview](/sql-statements/sql-statement-overview.md).
 
 ## Data Manipulation Language
 

expression-syntax.md

@@ -17,7 +17,7 @@ The expressions can be divided into the following types:
 
 - ParamMarker (`?`), system variables, user variables and CASE expressions.
 
-The following rules are the expression syntax, which is based on the [`parser.y`](https://github.com/pingcap/tidb/blob/release-8.1/pkg/parser/parser.y) rules of TiDB parser. For the navigable version of the following syntax diagram, refer to [TiDB SQL Syntax Diagram](https://pingcap.github.io/sqlgram/#Expression).
+The following rules are the expression syntax, which is based on the [`parser.y`](https://github.com/pingcap/tidb/blob/release-8.1/pkg/parser/parser.y) rules of TiDB parser.
 
 ```ebnf+diagram
 Expression ::=

mysql-compatibility.md

@@ -156,9 +156,7 @@ For more information, refer to [Understand the Query Execution Plan](/explain-ov
 
 ### Built-in functions
 
-TiDB supports most of the built-in functions in MySQL, but not all. You can use the statement `SHOW BUILTINS` to get a list of the available functions.
-
-For more information, refer to the [TiDB SQL Grammar](https://pingcap.github.io/sqlgram/#functioncallkeyword).
+TiDB supports most of the built-in functions in MySQL, but not all. You can use the statement [`SHOW BUILTINS`](/sql-statements/sql-statement-show-builtins.md) to get a list of the available functions.
 
 ### DDL operations