Difference between revisions of "KEY Table Constraint"
From Lianjapedia
Yvonne.milne (Talk | contribs) m (1 revision: SQL) |
Helen.george (Talk | contribs) |
||
| Line 1: | Line 1: | ||
==Purpose== | ==Purpose== | ||
Table constraint to define an index key | Table constraint to define an index key | ||
| − | |||
==Syntax== | ==Syntax== | ||
KEY [<cTagName>] (column1[, column2,...]) | KEY [<cTagName>] (column1[, column2,...]) | ||
| − | |||
==See Also== | ==See Also== | ||
[[ALTER TABLE]], [[SQL Constraints|CONSTRAINTS]], [[CREATE TABLE]] | [[ALTER TABLE]], [[SQL Constraints|CONSTRAINTS]], [[CREATE TABLE]] | ||
| − | |||
==Description== | ==Description== | ||
| Line 15: | Line 12: | ||
The KEY table constraint is used to define an index key. The index is built on the column or columns specified and given the name as defined in <cTagName>. The [[INDEX_Table_Constraint|INDEX]] table constraint can be used in the same way. | The KEY table constraint is used to define an index key. The index is built on the column or columns specified and given the name as defined in <cTagName>. The [[INDEX_Table_Constraint|INDEX]] table constraint can be used in the same way. | ||
| − | |||
==Example== | ==Example== | ||
| Line 24: | Line 20: | ||
</code> | </code> | ||
| − | |||
| − | |||
| − | |||
[[Category:Documentation]] | [[Category:Documentation]] | ||
[[Category:SQL]] | [[Category:SQL]] | ||
Latest revision as of 08:03, 7 December 2012
Contents
Purpose
Table constraint to define an index key
Syntax
KEY [<cTagName>] (column1[, column2,...])
See Also
ALTER TABLE, CONSTRAINTS, CREATE TABLE
Description
A constraint is used to define rules that help to provide data integrity. TABLE constraints apply to table-based operations. You must have ALTER privilege on the table. The table will be locked for EXCLUSIVE use during the operation.
The KEY table constraint is used to define an index key. The index is built on the column or columns specified and given the name as defined in <cTagName>. The INDEX table constraint can be used in the same way.
Example
CREATE TABLE contact; (LastName char(25), FirstName char(25),; KEY FullName (LastName, FirstName))
