SQL语句PART1
Oracle SQL(partI)
Data manipulation language(DML): select, insert, update, delete, merge.
Data definition language(DDL): create, alter, drop, rename, truncate, comment
Data control language(DCL): grant, revoke
Transaction control: commit, rollback, savepoint
Arithmetic Expressions:
+, -, *, /
1) Arithmetic expressions containing a null value evaluate to null
Column Alias
1) requires double quotation marks if it contains spaces or special characters, or if it is case-sensitive
e.g.: select last_name as name, commission_pct comm from employees;
e.g.: select last_name "Name", salary*12 "Annual Salary" from employees
Alternative Quote(q) Operator
e.g.: select depart_name||' Department'||q'['s Manager is ]'||manager_id as "Department and Manager"
results:
Department and Manager
Administrator Department's Manager is Me
...
Using DESCRIBE to display the table structure
e.g.: describe tb1;
Rules of precedence for operators in an expression
1 Arithmetic operators
2 Concatenation operator
3 Comparison conditions
4 IS [NOT] NULL, LIKE, [NOT] IN
5 [NOT] BETWEEN
6 Not equal to
7 NOT logical condition
8 AND logical condition
9 OR logical condition
e.g.: select last_name, job_id, salary from employees where job_id='SA_REP' or job_id='AD_PRES' and salary>15000;
means: select job_id='SA_REP' or (job_id='AD_PRES' and salary>15000)
e.g.: select last_name, job_id, salary from employees where (job_id='SA_REP' or job_id='AD_PRES') and salary>15000
Sorting:
can be sorted by column's numeric position
eg.: select last_name, job_id, department_id, hire_date from employees order by 3;
Substitution Variables
1. temporarily store values with & and &&
2. using in following conditions: where conditions, order by clauses, column expressions, table names, entire select statements.
e.g.: select employee_id, last_name, salary, department_id from employees where e
相关文档:
1. 当前系统日期、时间
select getdate()
2. dateadd 在向指定日期加上一段时间的基础上,返回新的 datetime 值
例如:向日期加上2天
&nbs ......
SQL Server 2005 日志删除和日志文件限制(转)
2009年08月04日 星期二 下午 04:40
清除日志:
DECLARE @LogicalFileName sysname,
@MaxMinutes INT,
@NewSize INT
USE szwzcheck ......
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
---- ---- --- ......
第十一题:
有表students(name,class,grade),请用标准sql语句完成
name class grade
张三 数学 81
李四 语文 70
王五 数学 90
张三 语文 60
李四 数学 100
王五 语文 90
王五 英语 81
要求: 用sql语句输出各门功课都大于80分的同学姓名?
create table students (
name varchar(25),
class varchar(25),
grad ......
--1加内存表
EXEC sp_tableoption '表名','pintable', 'true'
--2卸载内存表
EXEC sp_tableoption '表名','pintable', 'false'
--2查询是否有内存表驻留
SELECT * from INFORMATION_SCHEMA.Tables
WHERE TABLE_TYPE = 'BASE TABLE'
AND OBJECTPROP ......