1.The SQL introuduction
Introducing Oracle Database 11g
List the features of Oracle Database 11g
Discuss the basic design, theoretical and physical aspects of a relational database
Categorize the different types of SQL statements
Describe the data set used by the course
Log onto the database using the SQL Developer environment
Save queries to files and use script files in SQL Developer
Retrieving Data Using the SQL SELECT Statement
List the capabilities of SQL SELECT statements
Generate a report of data from the output of a basic SELECT statement
Select All Columns
Select Specific Columns
Use Column Heading Defaults
Use Arithmetic Operators
Understand Operator Precedence
Learn the DESCRIBE command to display the table structure
Restricting and Sorting Data
Write queries that contain a WHERE clause to limit the output retrieved
List the comparison operators and logical operators that are used in a WHERE clause
Describe the rules of precedence for comparison and logical operators
Use character string literals in the WHERE clause
Write queries that contain an ORDER BY clause sort the output of a SELECT statement
Sort output in descending and ascending order
Using Single-Row Functions to Customize Output
Describe the differences between single row and multiple row functions
Manipulate strings with character function in the SELECT and WHERE clauses
Manipulate numbers with the ROUND, TRUNC and MOD functions
Perform arithmetic with date data
Manipulate dates with the date functions
Using Conversion Functions and Conditional Expressions
Describe implicit and explicit data type conversion
Use the TO_CHAR, TO_NUMBER, and TO_DATE conversion functions
Nest multiple functions
Apply the NVL, NULLIF, and COALESCE functions to data
Use conditional IF THEN ELSE logic in a SELECT statement
Reporting Aggregated Data Using the Group Functions
Use the aggregation functions in SELECT statements to produce meaningful reports
Create queries that
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在SQL Server里查看当前连接的在线用户数
use master
select loginame,count(0) from sysprocesses
group by loginame
order by count(0) desc
select nt_username,count(0) from sysprocesses
group by nt_username
order by count(0) desc
如果某个SQL Server用户名test连接比较多,查看它来自的主机名:
......
1、select 1 from mytable;与select anycol(目的表集合中的任意一行） from mytable;与select * from mytable 作用上来说是没有差别的，都是查看是否有记录，一般是作条件用的。select 1 from 中的1是一常量，查到的所有行的值都是它，但从效率上来说，1>anycol>*，因为不用查字典表。
2、查看记录条数可以用select ......
SQL中CONVERT函数最常用的是使用convert转化长日期为短日期
如果只要取yyyy-mm-dd格式时间, 就可以用 convert(nvarchar(10),field,120)
120 是格式代码, nvarchar(10) 是指取出前10位字符.
SELECT CONVERT(nvarchar(10), getdate(), 120)
SELECT CONVERT(varchar(10), getdate(), 120)
SELECT CONVERT(char(10), ge ......
作者： sealyu 日期：2008-04-17
在SQL Server 中，如果给表的一个字段设置了默认值，就会在系统表sysobjects中生成一个默认约束。
如果想删除这个设置了默认值的字段（假设此字段名column1），
执行“ALTER TABLE table1 DROP COLUMN column1”时就会报错：
The object 'DF__xxxxxxxxxxx' ......
1. 创建视图：
CREATE OR REPLACE VIEW SM_V_UNIT_AUTH AS
SELECT T2.UNIT_ID,
T2.SUPER_UNIT_ID,
T1.AUTH_ID,
T1.AUTH_NAME,
T1.A ......
