sum(case when 性别 = '男' then 1 else 0 end ) 男生人数

这是一个 SQL 语句，用于统计性别为男的人数。具体来说，它会在一个表中查找名为“性别”的列，并将该列值为“男”的行计数。如果表名为“students”，则完整的 SQL 语句可能是这样的：

SELECT SUM(CASE WHEN 性别 = '男' THEN 1 ELSE 0 END) AS 男生人数 FROM students

执行后，将返回一个名为“男生人数”的列，其中包含性别为男的学生人数的值。

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

SELECT ak.dept_id deptId,ak.dept_name deptName,ak.parent_id parentId, IFNULL(pk.primaryShould,0) primaryShould,IFNULL(pk.primaryNot,0) primaryNot,IFNULL(pk.primaryGraduated,0) primaryGraduated, IFNULL(mk.middleShould,0) middleShould,IFNULL(mk.middleNot,0) middleNot,IFNULL(mk.middleGraduated,0) middleGraduated, IFNULL(hk.highShould,0) highShould,IFNULL(hk.highGraduated,0) highGraduated,IFNULL(hk.highNot,0) highNot FROM sys_dept ak LEFT JOIN (SELECT subordinate_school, SUM(CASE WHEN grade = 6 THEN 1 ELSE 0 END) primaryShould, SUM(CASE WHEN grade = 6 AND is_graduation = 'N' THEN 1 ELSE 0 END) primaryNot, SUM(CASE WHEN grade = 6 AND is_graduation = 'Y' THEN 1 ELSE 0 END) primaryGraduated FROM primary_school_roll WHERE primary_student_id LIKE concat('20', '%') GROUP BY subordinate_school) pk ON ak.dept_id = pk.subordinate_school LEFT JOIN (SELECT subordinate_school, SUM(CASE WHEN grade = 9 THEN 1 ELSE 0 END) middleShould, SUM(CASE WHEN grade = 9 AND is_graduation = 'N' THEN 1 ELSE 0 END) middleNot, SUM(CASE WHEN grade = 9 AND is_graduation = 'Y' THEN 1 ELSE 0 END) middleGraduated FROM middle_school_roll WHERE middle_student_id LIKE concat('20', '%') GROUP BY subordinate_school) mk ON ak.dept_id = mk.subordinate_school LEFT JOIN (SELECT subordinate_school, SUM(CASE WHEN grade = 12 THEN 1 ELSE 0 END) highShould, SUM(CASE WHEN graduation_way = '001' AND is_graduation = 'T' THEN 1 ELSE 0 END) highNot, SUM(CASE WHEN graduation_way = '000' AND is_graduation = 'Y' THEN 1 ELSE 0 END) highGraduated FROM high_school_roll WHERE high_student_id LIKE concat('20', '%') GROUP BY subordinate_school) hk ON ak.dept_id = hk.subordinate_school WHERE ak.state = 3 GROUP BY ak.dept_id

这是一条 SQL 查询语句，根据部门ID将三个子查询的结果进行合并，最终返回各部门的信息以及不同年级的学生人数及毕业情况。

具体实现过程是，使用 LEFT JOIN 连接 sys_dept 表和三个子查询的结果集，根据部门ID进行关联。在子查询中，使用 SUM() 函数对不同年级的学生人数进行求和，然后根据不同的条件进行分类统计。最后，使用 GROUP BY 对查询结果按部门ID进行分组，以得到每个部门的统计结果。

需要注意的是，这条查询语句中使用了 IFNULL() 函数对查询结果进行处理，以避免在统计结果为 NULL 时出现错误。同时，也需要注意在使用 LIKE 进行模糊查询时，应该使用索引来提高查询效率。