feat: show create database (#4642)

* feat: show create database

* feat: add sqlness test

* chore: reorder mod and use

* feat: show create schema

* Update src/frontend/src/instance.rs

src/sql/src/parsers/show_parser.rs

@@ -21,8 +21,9 @@ use crate::error::{
 };
 use crate::parser::ParserContext;
 use crate::statements::show::{
-    ShowColumns, ShowCreateFlow, ShowCreateTable, ShowCreateView, ShowDatabases, ShowFlows,
-    ShowIndex, ShowKind, ShowStatus, ShowTableStatus, ShowTables, ShowVariables, ShowViews,
+    ShowColumns, ShowCreateDatabase, ShowCreateFlow, ShowCreateTable, ShowCreateView,
+    ShowDatabases, ShowFlows, ShowIndex, ShowKind, ShowStatus, ShowTableStatus, ShowTables,
+    ShowVariables, ShowViews,
 };
 use crate::statements::statement::Statement;
 
@@ -74,7 +75,9 @@ impl<'a> ParserContext<'a> {
             // SHOW {INDEX | INDEXES | KEYS}
             self.parse_show_index()
         } else if self.consume_token("CREATE") {
-            if self.consume_token("TABLE") {
+            if self.consume_token("DATABASE") || self.consume_token("SCHEMA") {
+                self.parse_show_create_database()
+            } else if self.consume_token("TABLE") {
                 self.parse_show_create_table()
             } else if self.consume_token("FLOW") {
                 self.parse_show_create_flow()
@@ -109,6 +112,25 @@ impl<'a> ParserContext<'a> {
         }
     }
 
+    fn parse_show_create_database(&mut self) -> Result<Statement> {
+        let raw_database_name =
+            self.parse_object_name()
+                .with_context(|_| error::UnexpectedSnafu {
+                    expected: "a database name",
+                    actual: self.peek_token_as_string(),
+                })?;
+        let database_name = Self::canonicalize_object_name(raw_database_name);
+        ensure!(
+            !database_name.0.is_empty(),
+            InvalidDatabaseNameSnafu {
+                name: database_name.to_string(),
+            }
+        );
+        Ok(Statement::ShowCreateDatabase(ShowCreateDatabase {
+            database_name,
+        }))
+    }
+
     /// Parse SHOW CREATE TABLE statement
     fn parse_show_create_table(&mut self) -> Result<Statement> {
         let raw_table_name = self

src/sql/src/statements/show.rs

@@ -161,6 +161,19 @@ impl Display for ShowTableStatus {
     }
 }
 
+/// SQL structure for `SHOW CREATE DATABASE`.
+#[derive(Debug, Clone, PartialEq, Eq, Visit, VisitMut)]
+pub struct ShowCreateDatabase {
+    pub database_name: ObjectName,
+}
+
+impl Display for ShowCreateDatabase {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let database_name = &self.database_name;
+        write!(f, r#"SHOW CREATE DATABASE {database_name}"#)
+    }
+}
+
 /// SQL structure for `SHOW CREATE TABLE`.
 #[derive(Debug, Clone, PartialEq, Eq, Visit, VisitMut)]
 pub struct ShowCreateTable {

src/sql/src/statements/statement.rs

@@ -32,8 +32,9 @@ use crate::statements::insert::Insert;
 use crate::statements::query::Query;
 use crate::statements::set_variables::SetVariables;
 use crate::statements::show::{
-    ShowColumns, ShowCreateFlow, ShowCreateTable, ShowCreateView, ShowDatabases, ShowFlows,
-    ShowIndex, ShowKind, ShowStatus, ShowTableStatus, ShowTables, ShowVariables, ShowViews,
+    ShowColumns, ShowCreateDatabase, ShowCreateFlow, ShowCreateTable, ShowCreateView,
+    ShowDatabases, ShowFlows, ShowIndex, ShowKind, ShowStatus, ShowTableStatus, ShowTables,
+    ShowVariables, ShowViews,
 };
 use crate::statements::tql::Tql;
 use crate::statements::truncate::TruncateTable;
@@ -84,6 +85,8 @@ pub enum Statement {
     ShowCollation(ShowKind),
     // SHOW INDEX
     ShowIndex(ShowIndex),
+    // SHOW CREATE DATABASE
+    ShowCreateDatabase(ShowCreateDatabase),
     // SHOW CREATE TABLE
     ShowCreateTable(ShowCreateTable),
     // SHOW CREATE FLOW
@@ -139,6 +142,7 @@ impl Display for Statement {
             Statement::ShowCreateTable(s) => s.fmt(f),
             Statement::ShowCreateFlow(s) => s.fmt(f),
             Statement::ShowFlows(s) => s.fmt(f),
+            Statement::ShowCreateDatabase(s) => s.fmt(f),
             Statement::ShowCreateView(s) => s.fmt(f),
             Statement::ShowViews(s) => s.fmt(f),
             Statement::ShowStatus(s) => s.fmt(f),