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Learn/SQL/SQL References

SQL•SQL References

SQL ALTER Keyword

Concept visual

SQL ALTER Keyword

Pointer walk

two pointers

left=0

right=6

1

3

Start at both ends

ALTER Keyword

Alter Table

The ALTER TABLE

command adds, deletes, or modifies columns in a table.

The ALTER TABLE

command also adds and deletes various constraints in a table. The following SQL adds an "Email" column to the "Customers" table:

Example

ALTER TABLE Customers

ADD Email varchar(255);
The following SQL deletes the "Email" column from the "Customers" table:

Example

ALTER TABLE Customers

DROP COLUMN Email;

Alter Column

The ALTER COLUMN

command is used to change the data type of a column in a table. The following SQL changes the data type of the column named "BirthDate" in the "Employees" table to type year:

Example

ALTER TABLE Employees

ALTER COLUMN BirthDate year;

SQL ALTER Keyword

Concept visual

SQL ALTER Keyword

Pointer walk

two pointers

left=0

right=6

1

3

Start at both ends

ALTER Keyword

Alter Table

The ALTER TABLE

command adds, deletes, or modifies columns in a table.

The ALTER TABLE

command also adds and deletes various constraints in a table. The following SQL adds an "Email" column to the "Customers" table:

Example

ALTER TABLE Customers

ADD Email varchar(255);
The following SQL deletes the "Email" column from the "Customers" table:

Example

ALTER TABLE Customers

DROP COLUMN Email;

Alter Column

The ALTER COLUMN

command is used to change the data type of a column in a table. The following SQL changes the data type of the column named "BirthDate" in the "Employees" table to type year:

Example

ALTER TABLE Employees

ALTER COLUMN BirthDate year;

SQL ALTER Keyword

SQL ALTER Keyword

ALTER Keyword

Previous

Next

Alter Table

The ALTER TABLE

The ALTER TABLE

Example

ALTER TABLE Customers

Example

ALTER TABLE Customers

Alter Column

The ALTER COLUMN

Example

ALTER TABLE Employees

Previous

Next

SQL ALTER Keyword

SQL ALTER Keyword

ALTER Keyword

Previous

Next

Alter Table

The ALTER TABLE

The ALTER TABLE

Example

ALTER TABLE Customers

Example

ALTER TABLE Customers

Alter Column

The ALTER COLUMN

Example

ALTER TABLE Employees

Previous

Next