SQL Select 使用排序计数

Question

我有几行 Informix-4GL 代码执行以下操作

##
# prepare sql
##

let lv_sql = " select table.idno from table ",
             " where table.status != 'X' ",
             " and table.idno <= 10 ",
             " order by table.idno "
prepare table_sel from lv_sql
declare table_cur cursor for table_sel

##
# loop through results and count them
##

let count = 0

foreach table_cur into ti_num
   let count = count + 1
end foreach

display count

所以我得到特定 table 中按正确顺序排列少于 10 的行的总数，但我需要一个 foreach 循环来计算总数

我有第二种方法，我更喜欢

##
# prepare sql
##

let lv_sql = " select count(table.idno) from table ",
             " where table.idno in ( ",
             "    select table.idno from table "
             "    where table.status != 'X' ",
             "    and table.idno <= 10 ",
             " ) "
prepare table_sel from lv_sql

##
# just get result
##

execute table_sel into count

display count

问题是，如果我在 where in 过滤器中包含 order by 子句并且我需要它，那么第二个解决方案会崩溃，因为它的顺序并不总是正确的。有没有办法在这种情况下包含订单？

Answer 1

为什么不直接在代码的第一部分进行计数？

let lv_sql = " select count(table.idno) from table ",
         " where table.status != 'X' ",
         " and table.idno <= 10 ",
         " order by table.idno "

有效吗？

Answer 2

我认为你的问题在于你计算的方式。如果我没记错的话，你的 Select 计数将只检索一个值，我的意思是这个：

let lv_sql = " select count(table.idno) from table ",
             " where table.idno in ( ",
             "    select table.idno from table "
             "    where table.status != 'X' ",
             "    and table.idno <= 10 ",
             " ) "

因此，无需订购。如果您需要 table id 的引用和每个 Id 的计数，您需要将该字段添加到您的第一个 select 并在末尾添加一个 group by 子句，在订单之前根据你的需要，像这样：

let lv_sql = " select table.idno, count(table.idno) as counting from table ",
             " where table.idno in ( ",
             "    select table.idno from table "
             "    where table.status != 'X' ",
             "    and table.idno <= 10 ",
             " ) group by table.idno order by counting"

请告诉我这是否是您要找的东西

Answer 3

我一直在重新阅读问题并认为答案是...

let lv_sql = " select table.idno, count(*) ",
             " from table ",
             " where table.status != 'X' ",
             " and table.idno <= 10 ",
             " order by table.idno "
prepare table_sel from lv_sql
declare table_cur cursor for table_sel

foreach table_cur into l_idno, l_count
    ...
end foreach

...或者正如其他评论者所说，为什么顺序很重要？

SQL Select 使用排序计数

SQL Select Count using ordering

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