SQL Language---3

Database definition

I. Basic domain type: char,varchar,int,smallint,nimeric,real,double precision,float,boolean,date,time

Second, create a table

Statement format: creat table< table name > ...

Third, modify, delete the table

1. Modify: Alter table< table name >

2. Delete: Drop table< table name >

Iv. Creating and deleting indexes

1. Index classification: Clustered index, nonclustered index

2. Create: creat [unique][cluster][inddex< index name >ON< table name;]

(1) Order: ASC Ascending DSC Descending default value ascending

(2) Unique indicates that this index value corresponds to a unique data record

(3) CLUSTER clustered index

3. Delete: Drop index< index name >

V. Creation and deletion of views

1. Create: creat view name (list) as SELECT query clause [with CHECK OPTION]

2. Delete: Drop view name

SQL Language---3