oracle - 请 00302 : component DATA_TYPE must de declared in function

Question

我必须遵循 Oracle 函数 build_select，它创建一个选择请求。返回值格式如下:

select col1 ||'|'||col2 ||'|'||col3 from table;

下面是 build_select 函数:

create or replace FUNCTION build_select (
  p_table_name   IN VARCHAR2
)
    RETURN VARCHAR2
AS
    l_ret   VARCHAR2 (32767);
BEGIN
    FOR eachcol IN (  SELECT column_name, data_type
                           , LEAD (column_name), LEAD (data_type)
                                 OVER (
                                     PARTITION BY table_name ORDER BY column_id
                                 )
                                 next_column
                        FROM all_tab_cols
                       WHERE table_name = p_table_name
                    ORDER BY column_id)
    LOOP
      IF eachcol.data_type = 'CLOB' THEN
        l_ret   := l_ret || dbms_lob.substr( eachcol.column_name, 3000, 1 ) || CASE WHEN eachcol.next_column IS NULL THEN NULL ELSE ' ||''|''||' END;
      ELSE 
        l_ret   := l_ret || eachcol.column_name || CASE WHEN eachcol.next_column IS NULL THEN NULL ELSE ' ||''|''||' END;
      END IF;
    END LOOP;

    IF l_ret IS NULL
    THEN
        raise_application_error (-20001, 'table ' || p_table_name || ' not found');
    END IF;

    l_ret   := 'select ' || l_ret || ' from ' || p_table_name || ';';

    RETURN l_ret;
END build_select;

我想要做的是测试列的数据类型是否为 CLOB，如果是，则将其返回

dbms_lob.substr( eachcol.column_name, 3000, 1 )

我在循环部分添加了 if else 条件。但我收到错误:

PLS 00302 : component DATA_TYPE must de declared.

请帮忙吗？

我需要这样做，因为当我对返回的选择进行假脱机操作时，它不会返回 CLOB 数据类型的所有列。

Answer 1

我认为你的功能应该是这样的:

create or replace FUNCTION build_select (
  p_table_name   IN VARCHAR2
)
    RETURN VARCHAR2
AS
    l_ret   VARCHAR2 (32767);
BEGIN
    FOR eachcol IN (  SELECT column_name, data_type
                        FROM all_tab_cols
                       WHERE table_name = p_table_name
                    ORDER BY column_id)
    LOOP
      IF eachcol.data_type = 'CLOB' THEN
        l_ret   := l_ret || 'dbms_lob.substr( '||eachcol.column_name||', 3000, 1 ),';
      ELSE 
        l_ret   := l_ret || eachcol.column_name||',';
      END IF;
    END LOOP;

    IF l_ret IS NULL
    THEN
        raise_application_error (-20001, 'table ' || p_table_name || ' not found');
    END IF;

    l_ret   := 'select ' || regexp_replace(l_ret, ',$', NULL) || ' from ' || p_table_name || ';';

    RETURN l_ret;
END build_select;

请注意，ALL_TAB_COLS 还选择系统生成的隐藏列和不可见列，这可能会出现问题。如果您想过滤它们，请查询ALL_TAB_COLUMNS。