使用CASE。像这样。

SELECT Salable =
        CASE Obsolete
        WHEN 'N' THEN 1
        ELSE 0
    END

有多种情况。

SELECT

(CASE
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1001' THEN 'DM'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1002' THEN 'GS'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1003' THEN 'MB'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1004' THEN 'MP'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1005' THEN 'PL'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1008' THEN 'DM-27'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1011' THEN 'PB'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1012' THEN 'UT-2'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1013' THEN 'JGC'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1014' THEN 'SB'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1015' THEN 'IR'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1016' THEN 'UT-3'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1017' THEN 'UT-4'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1019' THEN 'KR'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1020' THEN 'SYB-SB'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1021' THEN 'GR'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1022' THEN 'SYB-KP'
WHEN RIGHT((LEFT(POSID,5)),4) LIKE '1026' THEN 'BNS'

  ELSE ''
END) AS OUTLET

FROM matrixcrm.Transact

SELECT
if((obsolete = 'N' OR instock = 'Y'), 1, 0) AS saleable, *
FROM
product;

使用CASE语句：

SELECT CASE
       WHEN (Obsolete = 'N' OR InStock = 'Y')
       THEN 'Y'
       ELSE 'N'
END as Available

etc...

为了完整起见，我想补充一点，SQL使用三值逻辑。表达式：

obsolete = 'N' OR instock = 'Y'

可能产生三种不同的结果：

| obsolete | instock | saleable |
|----------|---------|----------|
| Y        | Y       | true     |
| Y        | N       | false    |
| Y        | null    | null     |
| N        | Y       | true     |
| N        | N       | true     |
| N        | null    | true     |
| null     | Y       | true     |
| null     | N       | null     |
| null     | null    | null     |

例如，如果一个产品已经过时，但你不知道产品是否库存，那么你不知道该产品是否可销售。您可以按如下方式编写此三值逻辑：

SELECT CASE
           WHEN obsolete = 'N' OR instock = 'Y' THEN 'true'
           WHEN NOT (obsolete = 'N' OR instock = 'Y') THEN 'false'
           ELSE NULL
       END AS saleable

一旦确定了它的工作原理，就可以通过决定null的行为将三个结果转换为两个结果。例如，这会将null视为不可销售：

SELECT CASE
           WHEN obsolete = 'N' OR instock = 'Y' THEN 'true'
           ELSE 'false' -- either false or null
       END AS saleable

在这种情况下，案例陈述是您的朋友，采取以下两种形式之一：

简单的例子：

SELECT CASE <variable> WHEN <value>      THEN <returnvalue>
                       WHEN <othervalue> THEN <returnthis>
                                         ELSE <returndefaultcase>
       END AS <newcolumnname>
FROM <table>

扩展情况：

SELECT CASE WHEN <test>      THEN <returnvalue>
            WHEN <othertest> THEN <returnthis>
                             ELSE <returndefaultcase>
       END AS <newcolumnname>
FROM <table>

您甚至可以将case语句放在一个order by子句中进行真正的花式排序。