If statement 以公式为条件的if子句

在给定的查询中，我想给出条件：

if mha(material handling area) has name HB1(mha='HB1') then 
CAST(SUM(minloc) - SUM(noinloc) AS DECIMAL(6,0)) AS '_FREe places' divide with number 2.

怎么可能写出来呢？我尝试使用IF子句，但得到失败消息

SELECT mha, locstat, loctype, SUM(noinloc) '_Kolli', SUM(minloc) '_Plasser',
CAST(SUM(minloc) - SUM(noinloc) AS DECIMAL(6,0)) AS '_Free places''
FROM L30T1
GROUP BY mha, locstat, loctype
ORDER BY mha, locstat, loctype

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您使用什么语言？嘿，这是在SMSS:D结果中：选择mha、locstat、loctype、SUM（noinloc）‘uKolli’、IIF（mha=‘HB1’、SUM（minloc/2）、SUM（minloc））’、‘uPlasser’、IIF（mha=‘HB1’、SUM（minloc/2）－SUM（noinloc）、SUM（minloc）－SUM（noinloc））作为来自L30T1组的‘uTomme Plasser’、locstat、locstat、loctype、loctype、locstat、loctype、loctype、loctype