Difference between revisions of "PRIMARY KEY Table Constraint"
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==Example== | ==Example== | ||
<code lang="recital"> | <code lang="recital"> | ||
| − | + | CREATE TABLE newcust; | |
| − | CREATE TABLE newcust (acc_ref char(5) default strzero(seqno(),5), acc_name char(20)) | + | (acc_ref char(5) default strzero(seqno(),5),; |
| − | ALTER TABLE newcust ADD PRIMARY KEY acc_ref+acc_name TAG RefName | + | acc_name char(20)) |
| − | + | ||
| + | ALTER TABLE newcust; | ||
| + | ADD PRIMARY KEY acc_ref+acc_name TAG RefName | ||
</code> | </code> | ||
Latest revision as of 11:11, 22 December 2009
Purpose
Table constraint to define table's Primary Key
Syntax
PRIMARY KEY <expr> TAG <cTagName> [COLLATE <cCollateSequence>]
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 PRIMARY KEY table constraint is used to define <expr> as the table's Primary Key. The <expr> can contain any valid index key. A unique tag index is built on the specified <expr>; it is given the name as defined in <cTagName>. If a table already has a primary key defined, an error will be returned.
The optional COLLATE <cCollateSequence> clause is included for Visual FoxPro language compatibility only.
Example
CREATE TABLE newcust; (acc_ref char(5) default strzero(seqno(),5),; acc_name char(20)) ALTER TABLE newcust; ADD PRIMARY KEY acc_ref+acc_name TAG RefName
Products
Recital, Recital Server
