Difference between revisions of "Alter & Drop"
(Created page with "==Adding a Field== To add a column in a table, use the following syntax: <syntaxhighlight lang=sql> ALTER TABLE table_name ADD column_name datatype </syntaxhighlight> ==Dele...") |
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| + | You will not be asked any questions to do with alter or drop in your exam, however it could be useful for projects. | ||
==Adding a Field== | ==Adding a Field== | ||
To add a column in a table, use the following syntax: | To add a column in a table, use the following syntax: | ||
| Line 5: | Line 6: | ||
ALTER TABLE table_name | ALTER TABLE table_name | ||
ADD column_name datatype | ADD column_name datatype | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | Example: | ||
| + | |||
| + | <syntaxhighlight lang=sql> | ||
| + | ALTER TABLE Persons | ||
| + | ADD DateOfBirth date | ||
</syntaxhighlight> | </syntaxhighlight> | ||
==Deleting a Field== | ==Deleting a Field== | ||
| − | + | To delete the column named "DateOfBirth" in the "Persons" table you could use the following SQL statement: | |
| − | |||
| − | |||
<syntaxhighlight lang=sql> | <syntaxhighlight lang=sql> | ||
| Line 20: | Line 26: | ||
==Change Data Type== | ==Change Data Type== | ||
| − | + | To change the data type of the column named "DateOfBirth" in the "Persons" table you could use the following SQL statement: | |
| − | |||
<syntaxhighlight lang=sql> | <syntaxhighlight lang=sql> | ||
ALTER TABLE Persons | ALTER TABLE Persons | ||
ALTER COLUMN DateOfBirth year | ALTER COLUMN DateOfBirth year | ||
</syntaxhighlight> | </syntaxhighlight> | ||
Latest revision as of 14:26, 24 December 2016
You will not be asked any questions to do with alter or drop in your exam, however it could be useful for projects.
Adding a Field
To add a column in a table, use the following syntax:
ALTER TABLE table_name
ADD column_name datatype
Example:
ALTER TABLE Persons
ADD DateOfBirth date
Deleting a Field
To delete the column named "DateOfBirth" in the "Persons" table you could use the following SQL statement:
ALTER TABLE Persons
DROP COLUMN DateOfBirth
Change Data Type
To change the data type of the column named "DateOfBirth" in the "Persons" table you could use the following SQL statement:
ALTER TABLE Persons
ALTER COLUMN DateOfBirth year
