Question

我想循环遍历oracle中的表，在每列中找到空值，然后更新这些值，现在我试图只输出每列中的空值数，但我收到一条错误消息：

SET FEEDBACK OFF;
SET SERVEROUTPUT ON;

DECLARE
   N_NULLS       NUMBER;
   BEGIN
   FOR I IN (SELECT COLUMN_NAME
               FROM ALL_TAB_COLUMNS
              WHERE TABLE_NAME = 'my_table')
   LOOP
          SELECT SUM (CASE WHEN I IS NULL THEN 1 ELSE 0 END)
        INTO N_NULLS
        FROM my_table
       WHERE COLUMN_ITEM IS NULL;

      DBMS_OUTPUT.PUT_LINE ('NUMBER OF NULLS IN'|| I ||' IS ' || N_NULLS);
   END LOOP;
END;
/

我收到以下错误：

Error at line 10
ORA-06550: line 9, column 23:
PLS-00382: expression is of wrong type
ORA-06550: line 9, column 8:
PL/SQL: Statement ignored
ORA-06550: line 10, column 29:
PLS-00382: expression is of wrong type

Answer 1

@a_horse_with_no_name是正确的，您可以尝试以下代码在特定表的列中查找空行。

SET SERVEROUTPUT ON

DECLARE
    l_sql     VARCHAR2(4000);
    n_nulls   NUMBER;
BEGIN
    FOR i IN (
        SELECT
            column_name
        FROM
            all_tab_columns
        WHERE
            table_name = 'my_table'
    ) LOOP
        l_sql := ' SELECT SUM (CASE WHEN '
         || i.column_name
         || ' IS NULL THEN 1 ELSE 0 END)
        FROM my_table
       WHERE '
         || i.column_name
         || ' IS NULL';

        EXECUTE IMMEDIATE l_sql INTO
            n_nulls;
        dbms_output.put_line('NUMBER OF NULLS IN'
         || i.column_name
         || ' IS '
         || n_nulls);
    END LOOP;
END;
/

Answer 2

(CASE WHEN I IS NULL THEN 1 ELSE 0 END)

应该是

(CASE WHEN I.COLUMN_NAME IS NULL THEN 1 ELSE 0 END)

同样的问题：

DBMS_OUTPUT.PUT_LINE ('NUMBER OF NULLS IN'|| I ||' IS ' || N_NULLS);

循环遍历列并显示结果

2 个答案: