Question

我在SQL上运行查询时遇到了困难。我需要从我已在子查询中创建的字段中删除最后3个字符，然后根据该新字段加入。验证在第5行和第34行无效;无效的列名称＆＃39; PCD＆＃39;。＆＃34;

SELECT 
    *, LEFT(SUBQUERY.PC,Len(SUBQUERY.PC) -3) AS PCD 
FROM 
    (SELECT  
         PI.ClientPostcode, PI.casekey, 
         REPLACE( PI.ClientPostcode ,' ', '') As PC
     FROM PI
     WHERE LEN(PI.ClientPostcode) >= 5) AS SUBQUERY 
INNER JOIN 
     [Postcodes] On outcode = PCD

任何帮助将不胜感激

Answer 1

您无法在定义的同一级别上使用别名。

SELECT *, 
       LEFT(SUBQUERY.pc, Len(SUBQUERY.pc) - 3) AS PCD 
FROM   (SELECT pi.clientpostcode, 
               pi.casekey, 
               Replace(pi.clientpostcode, ' ', '') AS PC 
        FROM   pi 
        WHERE  Len(pi.clientpostcode) >= 5) AS SUBQUERY 
INNER JOIN [postcodes] 
       ON outcode = LEFT(SUBQUERY.pc, Len(SUBQUERY.pc) - 3) 
                    ^^^^ dont use the alias

或者你在像这样的子查询中使用它

SELECT *
FROM  ( 
        SELECT *, 
               LEFT(SUBQUERY.pc, Len(SUBQUERY.pc) - 3) AS PCD 
        FROM   (SELECT pi.clientpostcode, 
                       pi.casekey, 
                       Replace(pi.clientpostcode, ' ', '') AS PC 
                FROM   pi 
                WHERE  Len(pi.clientpostcode) >= 5) AS SUBQUERY 
      ) other_subq
INNER JOIN [postcodes] 
        ON outcode = other_subq.PCD

带有条件问题

1 个答案: