feat(database): improve getTableColumns method #80

- Refactored the getTableColumns method in GenSqlScriptBySelection.kt to use mapNotNull instead of flatMap for better performance.
- Added logging to display the table name and its corresponding columns for better debugging and understanding.

Author: phodal

exts/database/src/main/kotlin/cc/unitmesh/database/actions/GenSqlScriptBySelection.kt

@@ -197,13 +197,15 @@ data class DbContextActionProvider(val dasTables: List<DasTable>) {
      * @return A list of column names from the specified tables.
      */
     fun getTableColumns(tables: List<String>): List<String> {
-        return dasTables.flatMap { tableName ->
+        return dasTables.mapNotNull { tableName ->
             if (tables.contains(tableName.name)) {
-                DasUtil.getColumns(tableName).map {
+                val columns = DasUtil.getColumns(tableName).map {
                     "${it.name}: ${it.dasType.toDataType()}"
                 }
+
+                "TableName: ${tableName.name}, Columns: $columns"
             } else {
-                emptyList()
+                null
             }
         }
     }