Tsql T-SQL中的条件并集

目前我有一个查询，如下所示：

-- Query 1
SELECT
    acc_code, acc_name, alias, LAmt, coalesce(LAmt,0) AS amt 
FROM 
    (SELECT 
        acc_code, acc_name, alias, 
        (SELECT 
            (SUM(cr_amt)-SUM(dr_amt)) 
        FROM 
            ledger_mcg l
        WHERE 
            (l.acc_code LIKE a.acc_code + '.%' OR l.acc_code=a.acc_code) 
        AND 
            fy_id=1 
        AND
            posted_date BETWEEN '2010-01-01' AND '2011-06-02') AS LAmt 
    FROM
        acc_head_mcg AS a 
    WHERE 
    (acc_type='4')) AS T1
WHERE 
    coalesce(LAmt,0)<>0

仅当查询2返回的金额小于0时。否则，我不需要联合，只需要查询1的结果集

---

我能想到的最好的方法是创建一个参数化标量函数。如何才能最好地做到这一点？

您可以将第一个查询的结果存储到一个临时表中，然后，如果该表不是空的，则执行另一个查询

IF OBJECT_ID('tempdb..#MultipleQueriesResults') IS NOT NULL
  DROP TABLE #MultipleQueriesResults;

SELECT
    acc_code, acc_name, alias, LAmt, coalesce(LAmt,0) AS amt 
INTO #MultipleQueriesResults
FROM 
    (SELECT 
        acc_code, acc_name, alias, 
        (SELECT 
            (SUM(cr_amt)-SUM(dr_amt)) 
        FROM 
            ledger_mcg l
        WHERE 
            (l.acc_code LIKE a.acc_code + '.%' OR l.acc_code=a.acc_code) 
        AND 
            fy_id=1 
        AND
            posted_date BETWEEN '2010-01-01' AND '2011-06-02') AS LAmt 
    FROM
        acc_head_mcg AS a 
    WHERE 
    (acc_type='4')) AS T1
WHERE 
    coalesce(LAmt,0)<>0;

IF NOT EXISTS (SELECT * FROM #MultipleQueriesResults)
  … /* run Query 2 */

---

您可以将第一个查询的结果存储到一个临时表中，然后，如果该表不是空的，则执行另一个查询

IF OBJECT_ID('tempdb..#MultipleQueriesResults') IS NOT NULL
  DROP TABLE #MultipleQueriesResults;

SELECT
    acc_code, acc_name, alias, LAmt, coalesce(LAmt,0) AS amt 
INTO #MultipleQueriesResults
FROM 
    (SELECT 
        acc_code, acc_name, alias, 
        (SELECT 
            (SUM(cr_amt)-SUM(dr_amt)) 
        FROM 
            ledger_mcg l
        WHERE 
            (l.acc_code LIKE a.acc_code + '.%' OR l.acc_code=a.acc_code) 
        AND 
            fy_id=1 
        AND
            posted_date BETWEEN '2010-01-01' AND '2011-06-02') AS LAmt 
    FROM
        acc_head_mcg AS a 
    WHERE 
    (acc_type='4')) AS T1
WHERE 
    coalesce(LAmt,0)<>0;

IF NOT EXISTS (SELECT * FROM #MultipleQueriesResults)
  … /* run Query 2 */

---

只是一个观察：coalesclamt，0 AS amt列似乎是多余的，因为coalesclamt，00条件。只是一个观察：coalesclamt，0 AS amt列似乎是多余的，因为coalesclamt，00条件。好吧，需求有一点变化，查询本身也有一点变化。但是你的ans对我还是有帮助的。嗯，需求有了一点变化，查询本身也有了变化。但是你的ans对我还是有帮助的。