Database Review Summary (7)-creation of tables and insertion of commands, data modification, data deletion

One, the operation of the table

Tables: creating, modifying, deleting

all existing tables can be viewed through the select * from sysobjects where xtype= ' U '

Use commas to separate multiple columns

PRIMARY key:primary key

non-empty: notnull

Unique :unique

defaults: Default()

checking:check ()

foreign key:foreign KEY ( column name ) references table name ( column name )

For example:--Create a table

Use practicedbcreate table ClassInfo (CIdintNotNULLPrimary Key Identity (1,1), Ctitle nvarchar) CREATE table studentinfo (SIdintNotNULLPrimary Key Identity (1,1), SName nvarchar (Ten) notNULL, Sgender bitdefault(0), Sbirthday date, SphoneChar( One), Semail varchar ( -), CidintNotNULL, foreign KEY (CID) references ClassInfo (CID))

Second, the operation of the table data

-"Simple query: SELECT * FROM table name"
-"Add data: INSERT into table name (column name) values (value)
Illustration 1: The column name of the required value corresponds to the position of the value
Note 2: You can omit the column name section if all the more values are inserted
Extensions: Add multiple lines at once, and you can stitch multiple data directly behind the values, separated by commas
-"Modify data: Update table name set column name 1= value 1, column name 2= value 2 ... where ...
-delete data: Delete from table name where ...
Empty: TRUNCATE TABLE name
Description: The FROM keyword can be omitted without writing
Typically implemented: tombstone, physical Delete

Database Review Summary (7)-creation of tables and insertion of commands, data modification, data deletion