Difference between revisions of "SQLCHECKUNIQUE()"
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Yvonne.milne (Talk | contribs) |
Yvonne.milne (Talk | contribs) |
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==Syntax== | ==Syntax== | ||
− | SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>[, <lAllowblank | + | SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>[, <lAllowblank>]) |
==See Also== | ==See Also== | ||
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You should always provide a fully qualified database!table if your app is to work in Web/Mobile e.g "southwind!employees". | You should always provide a fully qualified database!table if your app is to work in Web/Mobile e.g "southwind!employees". | ||
− | The | + | The logical return value is .T. if the cKeyValue value already exists and .F. if it does not already exist in the cKeyField table column. |
{| class="wikitable" width="100%" | {| class="wikitable" width="100%" | ||
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|- | |- | ||
|valign="top"|lAllowblank||Logical expression specifying whether blank values should be ignored. | |valign="top"|lAllowblank||Logical expression specifying whether blank values should be ignored. | ||
− | |||
− | |||
|- | |- | ||
|} | |} | ||
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// Numeric cKeyField | // Numeric cKeyField | ||
nEmpIDUnique = sqlcheckunique("southwind!employees","employeeid","3") | nEmpIDUnique = sqlcheckunique("southwind!employees","employeeid","3") | ||
+ | // Ignore blanks | ||
+ | lCustIDUnique = sqlcheckunique("southwind!customers","customerid","''",.t.) | ||
+ | // Include blanks | ||
+ | lCustIDUnique = sqlcheckunique("southwind!customers","customerid","''",.f.) | ||
</code> | </code> | ||
Latest revision as of 07:29, 4 May 2020
Contents
Purpose
Function to check whether a prospective column value is unique
Syntax
SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>[, <lAllowblank>])
See Also
KEYLOOKUP(), LOOKUP(), RLOOKUP(), SEEK(), SET RELATION, SQLLOOKUP()
Description
The SQLCHECKUNIQUE() function checks the uniqueness of a prospective column value. The function will auto-detect if the specified table is a native Lianja table or a Virtual Table and act accordingly.
You should always provide a fully qualified database!table if your app is to work in Web/Mobile e.g "southwind!employees".
The logical return value is .T. if the cKeyValue value already exists and .F. if it does not already exist in the cKeyField table column.
Keywords | Description |
---|---|
cTable | Character expression to specify the table to be checked (native or Virtual Table). |
cKeyField | Character expression to specify the column in the table to be checked. |
cKeyValue | Character expression containing the value to be compared against cKeyField. If this is a character field then enclose it in quotes within quotes: " 'string' ". If it is a numeric then enclose it like this "1". |
lAllowblank | Logical expression specifying whether blank values should be ignored. |
Example
// Character cKeyField nCustIDUnique = sqlcheckunique("southwind!customers","customerid","'ALFKI'") // Numeric cKeyField nEmpIDUnique = sqlcheckunique("southwind!employees","employeeid","3") // Ignore blanks lCustIDUnique = sqlcheckunique("southwind!customers","customerid","''",.t.) // Include blanks lCustIDUnique = sqlcheckunique("southwind!customers","customerid","''",.f.)