Difference between revisions of "PRIMARY KEY Table Constraint"

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=PRIMARY KEY=
 
 
 
==Class==
 
Table Constraints
 
 
 
 
==Purpose==
 
==Purpose==
 
Table constraint to define table's Primary Key
 
Table constraint to define table's Primary Key
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==Example==
 
==Example==
 
<code lang="recital">
 
<code lang="recital">
set sql to vfp
+
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))
list structure index
+
 
 +
ALTER TABLE newcust;
 +
  ADD PRIMARY KEY acc_ref+acc_name TAG RefName
 
</code>
 
</code>
  
  
 
==Products==
 
==Products==
Recital Database Server, Recital Mirage Server, Recital Terminal Developer
+
Recital, Recital Server
 
[[Category:Documentation]]
 
[[Category:Documentation]]
 
[[Category:SQL]]
 
[[Category:SQL]]

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