Oracle 查询在运行时获取所有 COLUMN_NAMES，然后从每个 ROW w.r.t 获取值。每列

Question

我想要一个 Oracle sql 查询，它在运行时从特定 TABLE 中获取所有 COLUMN_NAMES，然后使用这些 COLUMN_NAMES 从每个 ROW 中获取值，考虑到我不知道 TABLE 中 COLUMNS 的数量和名称。

表 1：

COLUMN_1, COLUMN_2, COLUMN_3, COLUMN_4

value11 value12 value13 value14

value21 value22 value23 value24
...

作为 sql 查询的结果，我期望插入语句对应于每一行，如下所示：

INSERT INTO TABLE1 VALUES (value11,value12,value13,value14);

INSERT INTO TABLE1 VALUES (value21,value22,value23,value24);

...

我目前的做法如下：

查询 1

SELECT 'INSERT INTO TABLE1 VALUES (' ||COLUMN_1 ||',' ||COLUMN_2 ||',' ||COLUMN_3 ||',' ||COLUMN_4 ||');' AS INSERTSCRIPT FROM TABLE1 ORDER BY COLUMN_1;

使用它我得到了所需的插入语句，但问题是“我想避免为每个 TABLE 手动指定列名（因为有超过数百个这样的 TABLES）”。

所以我一直在尝试下一步：

查询 2)

SELECT LISTAGG(COLUMN_NAME, ', ') WITHIN GROUP (ORDER BY COLUMN_ID) FROM USER_TAB_COLS WHERE TABLE_NAME = 'TABLE1';

将列列为COLUMN_1, COLUMN_2, COLUMN_3, COLUMN_4 但问题是我无法在QUERY_1 中使用此结果

提前致谢！

Answer 1

  select 'select ' || LISTAGG(column_name , ',') within group (order by column_id) || ' from my_table' 
  from user_tab_columns 
  where table_name = 'MY_TABLE';

这样的查询将为您生成从MY_TABLE 中选择所有列的查询。

在 PL/SQL 中你可以这样做：

declare
querysql varchar2;
  select 'insert into my_table select ' || LISTAGG(column_name , ',') within group (order by column_id) || ' from my_table' into querysql 
    from user_tab_columns 
    where table_name = 'REFERENCE1';
  execute immediate querysql;
end;

Answer 2

我猜你需要 DML 生成器。类似的东西：

declare
  v_table_name varchar2(30) := 'YOUR_TABLE';

  v_date_mask varchar2(64) := 'dd.mm.yyyy hh24:mi:ss';
  v_sql varchar2(4000); 

  cur int;
  n   int;
  v_cols dbms_sql.desc_tab;

  v_varchar2 varchar2(10);
  v_number number;
  v_date date;

  v_column_list varchar2(4000);
  v_values_list varchar2(4000);
  v_single_value varchar2(4000);
begin
  v_sql := 'select * from ' || v_table_name;

  cur := dbms_sql.open_cursor;
  dbms_sql.parse(cur, v_sql, dbms_sql.native);

  dbms_sql.describe_columns(c => cur, col_cnt => n, desc_t => v_cols);

  for i in v_cols.first..v_cols.last
    loop
      case
        when v_cols(i).col_type = dbms_sql.Varchar2_Type
        then
          dbms_sql.define_column_char(c => cur, position => i, column => v_varchar2 , column_size => v_cols(i).col_max_len);
        when v_cols(i).col_type = dbms_sql.Number_Type
        then
          dbms_sql.define_column(c => cur, position => i, column => v_number);
        when v_cols(i).col_type = dbms_sql.Date_Type
        then
          dbms_sql.define_column(c => cur, position => i, column => v_date);
      end case;

      v_column_list := v_column_list || ',' || v_cols(i).col_name;   
    end loop;
  v_column_list := ltrim(v_column_list,',');    

  n := dbms_sql.execute(cur);

  n := dbms_sql.fetch_rows(cur);

  while (n > 0)
    loop
      for i in v_cols.first..v_cols.last
        loop
          case
            when v_cols(i).col_type = dbms_sql.Varchar2_Type
            then
              dbms_sql.column_value_char(c => cur, position => i, value => v_varchar2);
              v_single_value := case
                                 when v_varchar2 is not null
                                 then '''' || trim(v_varchar2) || ''''
                                 else 'NULL'
                                end;
            when v_cols(i).col_type = dbms_sql.Number_Type
            then
              dbms_sql.column_value(c => cur, position => i, value => v_number);
              v_single_value := nvl(to_char(v_number), 'NULL');
            when v_cols(i).col_type = dbms_sql.Date_Type
            then
              dbms_sql.column_value(c => cur, position => i, value => v_date);
              v_single_value := case
                                 when v_date is not null
                                 then 'to_date(''' || to_char(v_date, v_date_mask) || ''',''' || v_date_mask || ''')'
                                 else 'NULL'
                                end;
          end case;
          v_values_list := v_values_list || ',' || v_single_value;    
        end loop;
      v_values_list := ltrim(v_values_list,',');

      dbms_output.put_line ('INSERT INTO ' || v_table_name || '(' || v_column_list || ')');
      dbms_output.put_line ('  VALUES (' || v_values_list || ');' || chr(10));

      v_values_list := null;

      n := dbms_sql.fetch_rows(cur);
    end loop;

  dbms_sql.close_cursor(cur);
  exception
    when others then
      dbms_sql.close_cursor(cur);
      raise;
end;