如何利用这个SQL进行删除这些公司 出现次数-1的数量，只剩下一家这些公司SELECT company_name, COUNT(*) AS count FROM ( SELECT company_name, DENSE_RANK() OVER (ORDER BY company_name) AS company_rank FROM your_table_name ) AS subquery GROUP BY company_name HAVING COUNT(*) > 1;

要删除出现次数-1的数量，可以使用以下SQL语句：

DELETE FROM your_table_name
WHERE company_name IN (
    SELECT company_name
    FROM (
        SELECT company_name, COUNT(*) AS count
        FROM (
            SELECT company_name, DENSE_RANK() OVER (ORDER BY company_name) AS company_rank
            FROM your_table_name
        ) AS subquery
        GROUP BY company_name
    ) AS subquery2
    WHERE count = 1
);

这个语句会先将表中所有公司按照名称进行排序，并计算它们的排名。然后，将它们分组并计算每个公司出现的次数。最后，将出现次数为1的公司名称提取出来，并从原表中删除这些公司的所有记录。这样就可以保留只出现一次的公司，而将其他公司删除。

相关问题

如何利用这个SQL进行删除出现次数>2的公司，使>2的公司出现次数为1：SELECT company_name, COUNT() AS count FROM ( SELECT company_name, DENSE_RANK() OVER (ORDER BY company_name) AS company_rank FROM your_table_name ) AS subquery GROUP BY company_name HAVING COUNT() > 1;

要将出现次数大于2的公司出现次数变为1，可以使用以下SQL语句：

UPDATE your_table_name
SET company_name = 'new_name'
WHERE company_name IN (
    SELECT company_name
    FROM (
        SELECT company_name, COUNT(*) AS count
        FROM (
            SELECT company_name, DENSE_RANK() OVER (ORDER BY company_name) AS company_rank
            FROM your_table_name
        ) AS subquery
        GROUP BY company_name
        HAVING COUNT(*) > 2
    ) AS subquery2
);

DELETE FROM your_table_name
WHERE company_name IN (
    SELECT company_name
    FROM (
        SELECT company_name, COUNT(*) AS count
        FROM (
            SELECT company_name, DENSE_RANK() OVER (ORDER BY company_name) AS company_rank
            FROM your_table_name
        ) AS subquery
        GROUP BY company_name
        HAVING COUNT(*) > 2
    ) AS subquery3
);

这个语句会先将表中所有公司按照名称进行排序，并计算它们的排名。然后，将它们分组并计算每个公司出现的次数。接着，将出现次数大于2的公司名称提取出来，并将这些公司的名称更新为一个新的名称，例如'new_name'。最后，将这些公司的所有记录从原表中删除。这样就可以将出现次数大于2的公司出现次数变为1。

重写这段代码 CREATE OR REPLACE PROCEDURE ord_dev AS bill_date VARCHAR2(10); v_sql LONG; v_count NUMBER; v_time VARCHAR2(20); v_d VARCHAR2(2); v_m VARCHAR2(2); CURSOR c_tb IS SELECT * FROM b_cur_names; c_row b_cur_names%ROWTYPE; BEGIN EXECUTE IMMEDIATE 'truncate table b_cur_names'; v_sql := 'insert into b_cur_names Select TABLE_NAME from SYS.ALL_TABLES a Where a.owner =upper(''jour1'') And a.table_name Like upper(''om_subscriber_202___'') and Substr(a.table_name,-6) > 202205 order by 1'; COMMIT; EXECUTE IMMEDIATE 'DROP table ord_dev'; ---------------- v_sql := 'insert into ord_dev Select a.order_id,a.done_date, a.cust_id, a.subscriber_ins_id, a.access_num, c.dev_id, c.dev_name, c.corp_org, c.company_name, c.department_code, c.department_name, c.remarks From JOUR1.Om_Subscriber_202301 a Left Join JOUR1.om_order_202301 b On a.order_id = b.order_id Left Join params1.sec_developer c On b.dev_id = c.dev_id Where 1 =2 '; COMMIT; ------------- FOR c_row IN c_tb LOOP v_sql := ' insert into ord_dev Select a.order_id,a.done_date, a.cust_id, a.subscriber_ins_id, a.access_num, c.dev_id, c.dev_name, c.corp_org, c.company_name, c.department_code, c.department_name, c.remarks From JOUR1.Om_Subscriber_' || substr(c_row.table_name, -6) || ' a Left Join JOUR1.om_order_' || substr(c_row.table_name, -6) || ' b On a.order_id = b.order_id Left Join params1.sec_developer c On b.dev_id = c.dev_id Where 1 = 1 And a.access_num Like ''192%'' And a.action = 0'; COMMIT; END LOOP; END;

下面是重写后的优化代码：

CREATE OR REPLACE PROCEDURE ord_dev AS
v_sql VARCHAR2(32767);
v_count NUMBER;
v_time VARCHAR2(20);
v_d VARCHAR2(2);
v_m VARCHAR2(2);

BEGIN
-- Truncate b_cur_names table
EXECUTE IMMEDIATE 'TRUNCATE TABLE b_cur_names';

-- Get the table names matching the criteria
v_sql := 'INSERT INTO b_cur_names
SELECT TABLE_NAME FROM SYS.ALL_TABLES a
WHERE a.owner = UPPER(:owner)
AND a.table_name LIKE UPPER(:table_name_pattern)
AND SUBSTR(a.table_name,-6) > :table_name_suffix
ORDER BY 1';

EXECUTE IMMEDIATE v_sql USING 'jour1', 'OM_SUBSCRIBER_202___', '202205';

-- Drop ord_dev table if exists
BEGIN
EXECUTE IMMEDIATE 'DROP TABLE ord_dev';
EXCEPTION
WHEN OTHERS THEN NULL;
END;

-- Create ord_dev table
v_sql := 'CREATE TABLE ord_dev AS
SELECT a.order_id, a.done_date,
a.cust_id,
a.subscriber_ins_id,
a.access_num,
c.dev_id,
c.dev_name,
c.corp_org,
c.company_name,
c.department_code,
c.department_name,
c.remarks
FROM JOUR1.Om_Subscriber_202301 a
LEFT JOIN JOUR1.om_order_202301 b
ON a.order_id = b.order_id
LEFT JOIN params1.sec_developer c
ON b.dev_id = c.dev_id
WHERE 1 = 2';

EXECUTE IMMEDIATE v_sql;

-- Insert data into ord_dev table
FOR c_row IN (SELECT * FROM b_cur_names)
LOOP
v_sql := 'INSERT INTO ord_dev
SELECT a.order_id, a.done_date,
a.cust_id,
a.subscriber_ins_id,
a.access_num,
c.dev_id,
c.dev_name,
c.corp_org,
c.company_name,
c.department_code,
c.department_name,
c.remarks
FROM JOUR1.Om_Subscriber_' || SUBSTR(c_row.table_name, -6) || ' a
LEFT JOIN JOUR1.om_order_' || SUBSTR(c_row.table_name, -6) || ' b
ON a.order_id = b.order_id
LEFT JOIN params1.sec_developer c
ON b.dev_id = c.dev_id
WHERE 1 = 1
AND a.access_num LIKE ''192%''
AND a.action = 0';

EXECUTE IMMEDIATE v_sql;
COMMIT;
END LOOP;

END;
/

重写后的代码进行了以下优化：

1. 使用绑定变量：将动态SQL中的字面量值改为绑定变量，以提高执行计划的复用和安全性。

2. 使用异常处理：在DROP TABLE语句中添加异常处理机制，以处理表不存在的情况，避免抛出异常。

3. 使用CREATE TABLE语句：替换了使用INSERT INTO SELECT 1=2 的方式来创建空表，直接使用CREATE TABLE语句创建ord_dev表。

4. 使用FOR循环优化插入：使用FOR循环遍历b_cur_names表，动态构建INSERT INTO语句，将数据插入ord_dev表。

请根据实际需求进行测试和验证，确保代码逻辑正确并满足预期的功能。