4.SQL Server CREATE TABLE modification table

In the system, the table is divided into four kinds: 1. system table 2. Partition table 3. Temporary table 4. User-defined data table

1.Sql CREATE TABLE default column allows null

CREATE table table name (column name 1 data type, column name 2 data type, column name 3 data type,....)

Create Table  intnvarchar (255 Datetime image  notnull)

2. Create a temporary table

Not saved in the DB instance, just saved in the temporary buffer

 --  The local temporary table is only visible to the current user  create  table   #test (id  Span style= "COLOR: #0000ff" >int  not  null   varchar  (10   

-- Global Temp Table Create Table # #test (   intnotnull,   varchar( ),   nvarchar())

3. Set the column identity uniqueness is not duplicated

Select Table Right-click Design Select column Identity specification, insert data without inserting column ID field value

4. Default value when inserting column values this column defaults to a value

5. Create constraints such as column values are not allowed beyond a certain range ~ can only be applied to columns

The name and condition of the column is entered in the new constraint expression

6. Modify table Information

exec ' Test ' ' Test2 ' -- using Stored procedures to modify table  names -- parameter 1 Name of the original table -- parameter 2 new table name

-- Increase column modification (modify column data type) Delete column and so on use ALTER TABLE alter table Test2 add seniority int

7. Custom data types

Customizing data types based on system data types to use

8. When a rule inserts or updates data into a column of a table, it is used to limit the range of new values entered in the column ~

The difference between it and the constraint

Syntax for creating rules:

Create rule rule name expression of as rule ~ ~ ~

Ps:

Create Rule score  as @value between 0  and  - -- define a rule  definition variable @value used to standardize the range of values

To bind to a column in a specific data table after creating a rule

Using system stored procedures to implement

-- system stored procedure sp_bindrule

-- Parameter 1 score Create a good rule name

-- parameter 2 is bound to a specific table. Column Name

sp_bindrule score,' student grades, score '

9. Dismiss and delete rules

Unbind the rule to remove!!!

-- Unbind     -- parameter-specific bound columns ' student performance. Score ' -- Delete Rule Drop Rule Score

10. Data graphs better display the relationships between tables ~ ~

1. Right-click the new diagram

2. Add all the tables

3. Drag the column of the selected table to the table corresponding to the Add Relation column will pop up the Set Relationship dialog box set primary key and foreign key click OK

4.SQL Server CREATE TABLE modification table