text: SQL = {
      "TABLES":
          {
              "MYSQL": """
                          Select table_name,TABLE_COMMENT AS comment from INFORMATION_SCHEMA.TABLES 
                          Where table_schema = :db_name
                       """,
              "ORACLE": """
                      select table_name as "table_name",comments as "comment" from user_tab_comments order by table_name 
                      """
          },
      "COLUMNS": {
          "MYSQL": """
                         SELECT
                             COLUMN_NAME as column_name,
                              DATA_TYPE as data_type,
                              IFNULL(column_Comment,COLUMN_NAME) as comment,
                              ifnull(character_maximum_length,concat(numeric_precision,',',NUMERIC_SCALE)) as data_length,
                              case when `COLUMN_KEY` = 'PRI' then 1 else 0 end is_pk
                          
                           from INFORMATION_SCHEMA.COLUMNS t
                           Where table_name = :table_name AND 
                           table_schema = :db_name
                       """,
          "ORACLE": """
                  select
                      tc.column_name,
                      data_type,
                      cc.comments as "comment",
                      data_length,
                      data_precision,
                      tc.data_default,
                      case when con.constraint_type='P' then 1 else 0 end as "is_pk"
                  from  user_tab_columns tc left join user_col_comments cc
                                                      on tc.TABLE_NAME=cc.table_name and tc.COLUMN_NAME=cc.column_name
                                              left join user_cons_columns col on col.table_name=cc.table_name and col.column_name=cc.column_name and col.POSITION is not null
                                            left join user_constraints con
                                                      on con.constraint_name = col.constraint_name and con.constraint_type = 'P'
                       where tc.TABLE_NAME=:table_name
                      """
      },
  
  }
  