Using cursor record as arrays

Question

I have a pl\sql procedure that need to go over records in a curosr loop using dbms_sql package.

the cursor query is dynamic, so you don't know the columns.

so each time I want to use dbms_sql.define_columns or others functions I do it by a loop on all_tab_columns to get the columns names.

This is my code:

procedure p is

SOURCE_CURSOR      INTEGER; 
destination_cursor INTEGER; 
IGNORE             INTEGER; 
destination_cursor INTEGER; 
v_stmt clob := empty_clob();
V_COLS_LIST varchar2(4000);
V_COLS_LIST2 varchar2(4000);
V_UPDATE_DATE_COL_NAME varchar2(30) := 'UPDATE_DATE_COL';


begin

    -- going over all the records. each record is a table
    for CURR_TABLE in (select * from mng_tables)
    loop

        -- get the column list for the current table
        SELECT   LISTAGG(CLS.COLUMN_NAME, ',') WITHIN GROUP (ORDER BY COLUMN_ID)
        INTO     V_COLS_LIST
        FROM     ALL_TAB_COLUMNS CLS
        WHERE    CLS.TABLE_NAME = CURR_TABLE.HISTORY_TABLE_NAME
        AND      CLS.OWNER = CURR_TABLE.HISTORY_TABLE_OWNER
        AND      CLS.COLUMN_NAME <> V_UPDATE_DATE_COL_NAME;

        -- prepare the select from current table
        v_stmt := 'select ' || V_COLS_LIST || ', SYSDATE' ||
                  ' from ' || CURR_TABLE.TABLE_OWNER || '.' || CURR_TABLE.TABLE_NAME;

        -- prepare the dynamic sql        

        -- get cursor id
        source_cursor := dbms_sql.open_cursor; 

        -- parse cursor with query
        DBMS_SQL.PARSE(SOURCE_CURSOR,V_STMT, DBMS_SQL.NATIVE); 


        -- going over all the columns of current table and define matching columns
        FOR rec in (SELECT * 
                      FROM ALL_TAB_COLUMNS 
                      WHERE CLS.TABLE_NAME = CURR_TABLE.HISTORY_TABLE_NAME
                      AND       CLS.OWNER = CURR_TABLE.HISTORY_TABLE_OWNER)
        loop

            DBMS_SQL.DEFINE_COLUMN(source_cursor, rec.column_id, rec.data_type); 

        end loop;

        -- execute the select query
        IGNORE := DBMS_SQL.EXECUTE(SOURCE_CURSOR); 

        -- define the destination cursor
        destination_cursor := DBMS_SQL.OPEN_CURSOR; 

        select replace(V_COLS_LIST, ',' , ':,')
        into   V_COLS_LIST2
        from dual;

        -- parse the 
        DBMS_SQL.PARSE(destination_cursor, 
              'insert /*+ parallel(8) */ into ' || CURR_TABLE.HISTORY_TABLE_OWNER || '.' ||  CURR_TABLE.HISTORY_TABLE_NAME ||
              '(' || V_COLS_LIST || ',' || V_UPDATE_DATE_COL_NAME || ')' ||
                ' values (:' || V_COLS_LIST2 || ',sysdate)', 
               DBMS_SQL.NATIVE);


        LOOP 

        -- if there is a row
        IF DBMS_SQL.FETCH_ROWS(source_cursor)>0 THEN 

         FOR rec in (SELECT * 
                      FROM ALL_TAB_COLUMNS 
                      WHERE CLS.TABLE_NAME = CURR_TABLE.HISTORY_TABLE_NAME
                      AND       CLS.OWNER = CURR_TABLE.HISTORY_TABLE_OWNER)
        loop

         -- get column values of the row 
         DBMS_SQL.COLUMN_VALUE(source_cursor, rec.column_id, ???); 

         DBMS_SQL.BIND_VARIABLE(destination_cursor, ':' || rec.column_name, ???); 


        end loop;

        ignore := DBMS_SQL.EXECUTE(destination_cursor); 

      ELSE 

  -- No more rows to copy: 
        EXIT; 
      END IF; 


        end loop;


    end loop;

end p;

but when I want to bind the variables, I just can't do that becuase I can't have the values dynamically..

In the end of procedure when I'm doing that:

DBMS_SQL.COLUMN_VALUE(source_cursor, rec.column_id, ???); 

DBMS_SQL.BIND_VARIABLE(destination_cursor, ':' || rec.column_name, ???);

I just want to replace the ??? with something like "my_rec[rec.column_name]" or "my_rec[rec.column_id]" and get the value of the record in this column.

Any idea?

Thanks.

Answer 1

你正在使它变得更加复杂 - 而且效率低于它所需要的。您可以生成一个insert-as-select类型语句，每个表执行一次插入，而不是生成逐行插入并逐个选择和插入每一行：

create or replace procedure p is
    v_stmt clob;
    v_cols_list varchar2(4000);
    v_update_date_col_name varchar2(30) := 'UPDATE_DATE_COL';
begin
    -- going over all the records. each record is a table
    for curr_table in (select * from mng_tables)
    loop
        -- get the column list for the current table
        select   '"' || listagg(cls.column_name, '","')
            within group (order by column_id) || '"'
        into     v_cols_list
        from     all_tab_columns cls
        where    cls.table_name = curr_table.history_table_name
        and      cls.owner = curr_table.history_table_owner
        and      cls.column_name <> v_update_date_col_name;

        -- generate an insert-select statement
        v_stmt := 'insert into "' || curr_table.history_table_owner || '"'
                || '."' || curr_table.history_table_name || '"'
            || ' (' || v_cols_list || ', ' || v_update_date_col_name || ')'
            || ' select ' || v_cols_list || ', sysdate'
            || ' from "' || curr_table.table_owner || '"'
                || '."' || curr_table.table_name || '"';

        -- just for debugging
        dbms_output.put_line(v_stmt);

        execute immediate v_stmt;
    end loop;
end p;
/

我在所有所有者，表格和列名称周围添加了双引号，以防你有任何带引号的标识符，但是如果你确定你永远不会，那么它们就不是真的有必要了。

要回答你的实际问题，简单的暴力方法是声明一个字符串变量：

v_value varchar2(4000);

然后使用比column_value和bind_variable`调用：

DBMS_SQL.COLUMN_VALUE(source_cursor, rec.column_id, v_value); 
DBMS_SQL.BIND_VARIABLE(destination_cursor, rec.column_name, v_value); 

您发布的内容存在许多问题，当您在两个循环中没有CLS.TABLE_NAME别名时，从CLS等引用开始（也不排除你的V_UPDATE_DATE_COL_NAME专栏）;您的DEFINE_COLUMN调用未指定数据长度，因此对于字符串列不起作用;你的replace()将冒号放在逗号之前而不是之后;而且你要宣布destination_cursor两次。

但如果我理解了你的架构，那么这是有效的：

create or replace procedure p is

SOURCE_CURSOR      INTEGER; 
destination_cursor INTEGER; 
IGNORE             INTEGER; 
v_stmt clob := empty_clob();
V_COLS_LIST varchar2(4000);
V_COLS_LIST2 varchar2(4000);
V_UPDATE_DATE_COL_NAME varchar2(30) := 'UPDATE_DATE_COL';
v_value varchar2(4000);

begin

    -- going over all the records. each record is a table
    for CURR_TABLE in (select * from mng_tables)
    loop

        -- get the column list for the current table
        SELECT   LISTAGG(CLS.COLUMN_NAME, ',') WITHIN GROUP (ORDER BY COLUMN_ID)
        INTO     V_COLS_LIST
        FROM     ALL_TAB_COLUMNS CLS
        WHERE    CLS.TABLE_NAME = CURR_TABLE.HISTORY_TABLE_NAME
        AND      CLS.OWNER = CURR_TABLE.HISTORY_TABLE_OWNER
        AND      CLS.COLUMN_NAME <> V_UPDATE_DATE_COL_NAME;

        -- prepare the select from current table
        v_stmt := 'select ' || V_COLS_LIST || ', SYSDATE' ||
                  ' from ' || CURR_TABLE.TABLE_OWNER || '.' || CURR_TABLE.TABLE_NAME;

        -- prepare the dynamic sql        

        -- get cursor id
        source_cursor := dbms_sql.open_cursor; 

        -- parse cursor with query
        DBMS_SQL.PARSE(SOURCE_CURSOR,V_STMT, DBMS_SQL.NATIVE); 


        -- going over all the columns of current table and define matching columns
        FOR rec in (SELECT * 
                      FROM ALL_TAB_COLUMNS CLS
                      WHERE CLS.TABLE_NAME = CURR_TABLE.HISTORY_TABLE_NAME
                      AND       CLS.OWNER = CURR_TABLE.HISTORY_TABLE_OWNER
                      AND       CLS.COLUMN_NAME <> V_UPDATE_DATE_COL_NAME)
        loop

            DBMS_SQL.DEFINE_COLUMN(source_cursor, rec.column_id, rec.data_type, rec.data_length); 

        end loop;

        -- execute the select query
        IGNORE := DBMS_SQL.EXECUTE(SOURCE_CURSOR); 

        -- define the destination cursor
        destination_cursor := DBMS_SQL.OPEN_CURSOR;

        select replace(V_COLS_LIST, ',' , ',:')
        into   V_COLS_LIST2
        from dual;

        -- parse the 
        DBMS_SQL.PARSE(destination_cursor, 
              'insert /*+ parallel(8) */ into ' || CURR_TABLE.HISTORY_TABLE_OWNER || '.' ||  CURR_TABLE.HISTORY_TABLE_NAME ||
              '(' || V_COLS_LIST || ',' || V_UPDATE_DATE_COL_NAME || ')' ||
                ' values (:' || V_COLS_LIST2 || ',sysdate)', 
               DBMS_SQL.NATIVE);


        LOOP 

        -- if there is a row
        IF DBMS_SQL.FETCH_ROWS(source_cursor)>0 THEN 

         FOR rec in (SELECT * 
                      FROM ALL_TAB_COLUMNS CLS
                      WHERE CLS.TABLE_NAME = CURR_TABLE.HISTORY_TABLE_NAME
                      AND       CLS.OWNER = CURR_TABLE.HISTORY_TABLE_OWNER
                      AND       CLS.COLUMN_NAME <> V_UPDATE_DATE_COL_NAME)
        loop

         -- get column values of the row 
         DBMS_SQL.COLUMN_VALUE(source_cursor, rec.column_id, v_value); 

         DBMS_SQL.BIND_VARIABLE(destination_cursor, rec.column_name, v_value); 


        end loop;

        ignore := DBMS_SQL.EXECUTE(destination_cursor); 

        dbms_sql.close_cursor(destination_cursor);
      ELSE 

  -- No more rows to copy: 
        EXIT; 
      END IF; 


        end loop;


    end loop;

end p;
/

最好有一个每个可能的数据类型的变量，并使用case语句为每列调用column_value和bind_variable`与正确类型的变量，因此您不依赖于隐式转换往返于字符串（尤其是日期问题 - 根据会话NLS设置可能会丢失精度）。