feat: add QuestDB support

Thanks @ptma!

crates/dbx-core/src/sql_dialect/identifiers.rs

@@ -41,7 +41,8 @@ pub fn quote_table_identifier(database_type: Option<DatabaseType>, name: &str) -
             | DatabaseType::Databend
             | DatabaseType::Tdengine
             | DatabaseType::Access
-            | DatabaseType::Bigquery,
+            | DatabaseType::Bigquery
+            | DatabaseType::Questdb,
         ) => {
             format!("`{}`", name.replace('`', "``"))
         }
@@ -69,7 +70,8 @@ pub(crate) fn quote_transfer_identifier(name: &str, database_type: &DatabaseType
         | DatabaseType::ClickHouse
         | DatabaseType::Doris
         | DatabaseType::StarRocks
-        | DatabaseType::Hive => format!("`{}`", name.replace('`', "``")),
+        | DatabaseType::Hive
+        | DatabaseType::Questdb => format!("`{}`", name.replace('`', "``")),
         DatabaseType::SqlServer => format!("[{}]", name.replace(']', "]]")),
         _ => format!("\"{}\"", name.replace('\"', "\"\"")),
     }
@@ -77,7 +79,8 @@ pub(crate) fn quote_transfer_identifier(name: &str, database_type: &DatabaseType
 
 pub(crate) fn qualified_transfer_table(table_name: &str, schema: &str, database_type: &DatabaseType) -> String {
     let table = quote_transfer_identifier(table_name, database_type);
-    if schema.is_empty() || matches!(database_type, DatabaseType::Mysql | DatabaseType::MongoDb) {
+    if schema.is_empty() || matches!(database_type, DatabaseType::Mysql | DatabaseType::MongoDb | DatabaseType::Questdb)
+    {
         table
     } else {
         format!("{}.{}", quote_transfer_identifier(schema, database_type), table)

crates/dbx-core/src/sql_dialect/table_select.rs

@@ -110,6 +110,17 @@ pub fn build_table_data_select_sql(options: TableDataSelectSqlOptions) -> String
         );
     }
 
+    if database_type == Some(DatabaseType::Questdb) {
+        return build_questdb_table_select_sql(
+            &table_alias,
+            &where_clause,
+            &order,
+            &options.columns,
+            limit,
+            options.offset.unwrap_or(0),
+        );
+    }
+
     let offset =
         options.offset.filter(|offset| *offset > 0).map(|offset| format!(" OFFSET {offset}")).unwrap_or_default();
     format!("SELECT {select_columns} FROM {table_alias}{where_clause}{order} LIMIT {limit}{offset};")
@@ -332,3 +343,27 @@ pub(super) fn build_neo4j_table_select_sql(options: &TableDataSelectSqlOptions,
     let skip = options.offset.filter(|offset| *offset > 0).map(|offset| format!(" SKIP {offset}")).unwrap_or_default();
     format!("MATCH (n:{label}){where_clause} RETURN {returns}{order}{skip} LIMIT {limit};")
 }
+
+pub(super) fn build_questdb_table_select_sql(
+    table: &str,
+    where_clause: &str,
+    order_by: &str,
+    columns: &[String],
+    limit: usize,
+    offset: usize,
+) -> String {
+    let columns_sql = if columns.is_empty() {
+        "*".to_string()
+    } else {
+        columns
+            .iter()
+            .map(|column| quote_table_identifier(Some(DatabaseType::Questdb), column))
+            .collect::<Vec<_>>()
+            .join(", ")
+    };
+    if offset == 0 {
+        return format!("SELECT {columns_sql} FROM {table}{where_clause}{order_by} LIMIT {limit}");
+    }
+    let upper_bound = offset + limit;
+    return format!("SELECT {columns_sql} FROM {table}{where_clause}{order_by} LIMIT {offset}, {upper_bound}");
+}