case when xb = '男' then 1 else 0 end

这是一个SQL语句中的CASE WHEN表达式，它的作用是将性别为男的学生计为1，其他性别的学生计为0。在这个表达式中，当性别为男时，返回1，否则返回0。这个表达式通常用于统计男女人数或者计算某个条件下的数量。下面是一个示例：

SELECT SUM(CASE WHEN xb = '男' THEN 1 ELSE 0 END) AS "男生总数",
       SUM(CASE WHEN xb = '女' THEN 1 ELSE 0 END) AS "女生总数"
FROM student;

这个示例中，我们使用了两个CASE WHEN表达式来统计男女人数。第一个表达式统计男生总数，第二个表达式统计女生总数。在每个表达式中，当性别为男或女时，返回1，否则返回0。最后使用SUM函数将所有的1相加，得到男女人数的总和。

相关问题

clickhouse数据库，请找出这段sql中的错误并修正SELECT (case when org_type is null or org_type = '' then '未知' else org_type end) AS org_type, (case when type is null or type = '' then '未知' else type end) AS type, (case when fine_type_code is null or fine_type_code = '' then '未知' else fine_type_code end) AS fine_type_name, org_id, count(id) AS count, SUM(CASE WHEN status=7 THEN 1 ELSE 0 END) AS undistributed, SUM(CASE WHEN status=3 THEN 1 ELSE 0 END) AS inProcess, SUM(CASE WHEN status=4 THEN 1 ELSE 0 END) AS unchecked, SUM(CASE WHEN status=5 THEN 1 ELSE 0 END) AS completed FROM analysis.ods_biz_order_record_view GROUP BY (1, 2, 3, 4) ORDER BY count desc

这段 SQL 语句的语法是正确的，但在 GROUP BY 子句中使用了位置索引，这是不推荐的。建议使用列名而不是位置索引来指定分组的列。下面是修正后的 SQL：

SELECT
(CASE WHEN org_type IS NULL OR org_type = '' THEN '未知' ELSE org_type END) AS org_type,
(CASE WHEN type IS NULL OR type = '' THEN '未知' ELSE type END) AS type,
(CASE WHEN fine_type_code IS NULL OR fine_type_code = '' THEN '未知' ELSE fine_type_code END) AS fine_type_name,
org_id,
COUNT(id) AS count,
SUM(CASE WHEN status=7 THEN 1 ELSE 0 END) AS undistributed,
SUM(CASE WHEN status=3 THEN 1 ELSE 0 END) AS inProcess,
SUM(CASE WHEN status=4 THEN 1 ELSE 0 END) AS unchecked,
SUM(CASE WHEN status=5 THEN 1 ELSE 0 END) AS completed
FROM analysis.ods_biz_order_record_view
GROUP BY org_type, type, fine_type_name, org_id
ORDER BY count DESC

DECLARE @nmSupport NUMERIC(14,4),@nmOutst NUMERIC(14,4),@chPart VARCHAR(16) SELECT @chPart = 'XXX' SELECT @nmOutst = 0 SELECT @nmSupport = 0 UPDATE acdb.PAC06.AC06004A SET nmSupport = CASE WHEN chPart = @chPart THEN CASE WHEN nmQty > @nmOutst THEN @nmOutst ELSE nmQty END ELSE CASE WHEN nmQty > nmOutst THEN nmOutst ELSE nmQty END END, nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-nmSupport END, @nmOutst = CASE WHEN chPart = @chPart then case when @nmOutst>=@nmSupport then @nmOutst-@nmSupport else 0 end else nmOutst-nmSupport END, @nmSupport = case when chPart = @chPart then case when nmQty > @nmOutst then @nmOutst else nmQty end ELSE CASE WHEN nmQty > nmOutst THEN nmOutst ELSE nmQty END end, @chPart = chPart改成用游标遍历的方式

好的，以下是将代码改写为使用游标遍历的方式：

DECLARE @nmSupport NUMERIC(14,4), @nmOutst NUMERIC(14,4), @chPart VARCHAR(16)

-- 声明游标
DECLARE cur CURSOR FOR
SELECT chPart, nmQty, nmOutst, nmSupport
FROM acdb.PAC06.AC06004A

-- 初始化变量
SET @chPart = 'XXX'
SET @nmOutst = 0
SET @nmSupport = 0

-- 打开游标
OPEN cur

-- 循环遍历游标中的每一行数据
FETCH NEXT FROM cur INTO @chPart, @nmQty, @nmOutst, @nmSupport
WHILE @@FETCH_STATUS = 0
BEGIN
    -- 更新 nmSupport 和 nmOutst 字段的值
    UPDATE acdb.PAC06.AC06004A
    SET nmSupport = CASE 
                        WHEN chPart = @chPart 
                        THEN CASE 
                            WHEN nmQty > @nmOutst 
                            THEN @nmOutst 
                            ELSE nmQty 
                            END 
                        ELSE CASE 
                            WHEN nmQty > nmOutst 
                            THEN nmOutst 
                            ELSE nmQty 
                            END 
                    END,
        nmOutst = CASE 
                    WHEN chPart = @chPart 
                    THEN CASE 
                        WHEN @nmOutst >= @nmSupport 
                        THEN @nmOutst - @nmSupport 
                        ELSE 0 
                        END 
                    ELSE nmOutst - nmSupport 
                    END
    WHERE CURRENT OF cur
    
    -- 更新变量的值
    SET @nmOutst = CASE 
                    WHEN chPart = @chPart 
                    THEN CASE 
                        WHEN @nmOutst >= @nmSupport 
                        THEN @nmOutst - @nmSupport 
                        ELSE 0 
                        END 
                    ELSE nmOutst - nmSupport 
                    END
    SET @nmSupport = CASE 
                        WHEN chPart = @chPart 
                        THEN CASE 
                            WHEN nmQty > @nmOutst 
                            THEN @nmOutst 
                            ELSE nmQty 
                            END 
                        ELSE CASE 
                            WHEN nmQty > nmOutst 
                            THEN nmOutst 
                            ELSE nmQty 
                            END 
                        END
    SET @chPart = chPart
    
    -- 继续遍历下一行数据
    FETCH NEXT FROM cur INTO @chPart, @nmQty, @nmOutst, @nmSupport
END

-- 关闭游标
CLOSE cur
DEALLOCATE cur

以上代码使用游标遍历了表中的每一行数据，并按原代码的逻辑更新了 nmSupport 和 nmOutst 字段的值。同时，变量的更新也改为了在循环中进行。