SQL语句PART9
Group functions
SELECT [column,] group_function(column) ... from table [WHERE condition] [GROUP BY group_by_expression] [ORDER BY column];
e.g.:
SELECT department_id, job_id, SUM(salary), COUNT(employee_id) from employees GROUP BY department_id, job_id ;
SELECT [column,] group_function(column)... from table [WHERE condition] [GROUP BY group_by_expression]
[HAVING having_expression] [ORDER BY column];
GROUP BY with ROLLUP and CUBE Operators
1. Use ROLLUP or CUBE with GROUP BY to produce superaggregate rows by cross-referencing columns.
2. ROLLUP grouping produces a result set containing the regular grouped rows and the subtotal values.
3. CUBE grouping produces a result set containing the rows from ROLLUP and cross-tabulation rows.
SELECT [column,] group_function(column). . .from table [WHERE condition] [GROUP BY [ROLLUP] group_by_expression] [HAVING having_expression];[ORDER BY column];
//ROLLUP is an extension to the GROUP BY clause Use the ROLLUP operation to produce cumulative
aggregates, such as subtotals.
e.g. :
select nmoduleinfoid, ndocsortid, salary from t1;
1 1 1000
1 2 2100
1 3 1300
2 4 1400
select nmoduleinfoid, ndocsortid, sum(salary) from t1 group by rollup(nmoduleinfoid, ndocsortid);
1 1 1000
1 2 2100
1 3 1300
1 4400
2 4 1400
2 1400
5800
SELECT [column,] group_function(column)... from table [WHERE condition] [GROUP BY [CUBE] group_by_expression] [HAVING having_expression] [ORDER BY column];
// CUBE is an extension to the GROUP BY clause. You can use the CUBE operator to produce cross-tabulation
相关文档：
问题：假设有张学生成绩表(tb)如下:
姓名 课程 分数
张三 语文 74
张三 数学 83
张三 物理 93
李四 语文 74
李四 数学 84
李四 物理 94
想变成(得到如下结果)：
姓名 语文 数学 物理
---- ---- --- ......
PL/SQL: Oracle中的SQL过程化编程语言
1. PL/SQL程序是由块结构构成，格式如下：
[DECLARE
--声明部分
]
BEGIN
-- 主体
[EXCEPTION
-- 异常处理块
]
END;
/ --块的结束
2.变量
简单变量： ......
constraint Example:
1. grammer:
create table [schema.]table
(column datatype [DEFAULT expr]
[column_constraint], ...
[table_constraint] [,......]);
2. example of a column_level constraint:
create table empl ......
CREATE VIEW MYVIEW
AS
SELECT * from bjxxdiweb_database2007.dbo.bm_tongji
UNION ALL
SELECT * from aa.DBO.chen
select * into aa..chen from bjxxdiweb_database2007.dbo.bm_tongji where 1=2
说明：数据库A的表的字段名必须和数据库B的表的字段名相同，包括数据类型等。 ......
PairWise subquery:
e.g.:
select * from wf_docsort where (ndocsortid,nmoduleinfoid) in (select ndocsortid, nmoduleinfoid from wf_docsort where instr(cname,'文')>0)
the above sql is the same function as:
select * from wf_docsort where ndocsortid = (select ndocsortid from wf_docsort where ......
