SQL method for determining whether a field Column exists

Add Field
Copy codeThe Code is as follows:
Alter table docdsp add dspcode char (200)

Delete Field
Copy codeThe Code is as follows:
Alter table table_NAME drop column column_NAME

Modify Field Type
Copy codeThe Code is as follows:
Alter table table_name alter column column_name new_data_type

Rename
Sp_rename
Change the name of the user-created object (such as a table, column, or user-defined data type) in the current database.
Syntax
Copy codeThe Code is as follows:
Sp_rename [@ objname =] 'object _ name ',
[@ Newname =] 'new _ name'
[, [@ Objtype =] 'object _ type']

-- Assume that the table to be processed is named tb.

-- Determines whether the table to be added has a primary key.
If exists (select 1 from sysobjects where parent_obj = object_id ('tb') and xtype = 'pk ')
Begin
Print 'The table already has a primary key, and the column can only be added as a normal column'

-- Add an int column. The default value is 0.
Alter table tb add column name int default 0
End
Else
Begin
Print 'table with no primary key, add primary key column'

-- Add an int column. The default value is 0.
Alter table tb add column name int primary key default 0
End
/*************************************** **************************************** *******/

Determine whether the name field exists in table1
Copy codeThe Code is as follows:
If exists (select * from syscolumns where id = object_id ('table1') and name = 'name') begin
Select * from people;
End