Modify the SQL command Sql-server database table structure with SQL command line modify database _mssql

No nonsense, please see the code detailed below.

Add a varchar column to the table:

ALTER TABLE Distributors ADD COLUMN address varchar (30);

To delete a field from a table:

ALTER TABLE Distributors DROP COLUMN address RESTRICT;

To modify the type of two existing fields in one operation:

ALTER TABLE Distributors
ALTER COLUMN address TYPE varchar (80),
ALTER COLUMN name TYPE varchar (100);

Converts an integer field containing the UNIX timestamp to timestamp with time zone using a using clause:

ALTER TABLE foo
ALTER COLUMN foo_timestamp TYPE timestamp with time zone
USING
Timestamp with time zone ' epoch ' + foo_timestamp * interval ' 1 second ';

To rename an existing field:

ALTER TABLE Distributors RENAME COLUMN address to City;

Change the name of an existing table:

ALTER TABLE Distributors RENAME to suppliers;

Add a Non-empty constraint to a field:

ALTER TABLE distributors ALTER COLUMN Street SET is not NULL;

Removes a Non-empty constraint from a field:

ALTER TABLE distributors ALTER COLUMN Street DROP not NULL;

Add a check constraint to a table:

ALTER TABLE Distributors ADD CONSTRAINT zipchk CHECK (char_length (zipcode) = 5);

Deletes the OMV constraint for a table and all of its child tables:

ALTER TABLE Distributors DROP CONSTRAINT Zipchk;

Add a FOREIGN KEY constraint to the table:

ALTER TABLE Distributors ADD CONSTRAINT DISTFK FOREIGN KEY (address) REFERENCES addresses [address] MATCH full;

Add a (multiple-field) Unique constraint to a table:

ALTER TABLE Distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, ZipCode);

To add an automatically named PRIMARY KEY constraint to a table, note that a table can have only one primary key:

ALTER TABLE Distributors ADD PRIMARY KEY (dist_id);

To move a table to another table space:

ALTER TABLE Distributors SET tablespace fasttablespace;

Ps:sql the command line to modify the database

Add Columns:

ALTER TABLE tablename add columnName varchar (30)

To modify a column type:

ALTER TABLE tablename ALTER COLUMN COLUMNNAME varchar (4000)

To modify the name of a column:

EXEC sp_rename ' tablename.column1 ', ' column2 ' (change the Column1 column name of the table name TableName to Column2)

To delete a column:

ALTER TABLE tablename DROP column ColumnName

The above content is the whole narration of this article, hope to be helpful to everybody.