Difference between revisions of "Alter & Drop"
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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: | ||
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<syntaxhighlight lang=sql> | <syntaxhighlight lang=sql> | ||
ALTER TABLE Persons | ALTER TABLE Persons | ||
| − | ADD | + | 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 27: | 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 13:26, 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
