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SQL how to determine whether the field column exists, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can gain something.

The copy code for adding fields is as follows: alter table docdsp add dspcode char

The copy code for deleting fields is as follows: ALTER TABLE table_NAME DROP COLUMN column_NAME

The copy code for modifying the field type is as follows: ALTER TABLE table_name ALTER COLUMN column_name new_data_type

Rename sp_rename changes the name of a user-created object in the current database, such as a table, column, or user-defined data type. The syntax copy code is as follows: sp_rename [@ objname =] 'object_name', [@ newname =]' new_name' [, [@ objtype =] 'object_type']

-- suppose the table to be processed is named: tb

-- determine whether there is a primary key in the table to which the column is to be added. If exists (select 1 from sysobjects where parent_obj=object_id ('tb') and xtype='PK') beginprint' table already has a primary key. Columns can only be added as ordinary columns.'

-- add a column of type int. The default value is 0alter table tb add column name int default 0 endelsebeginprint'No primary key in the table, add primary key column'

-add a column of type int. The default value is 0alter table tb add column name int primary key default 0 end/*/

To determine whether there is a name field in table1, the copy code is as follows: if exists (select * from syscolumns where id=object_id ('table1') and name='name') beginselect * from people;end

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